133N. Wilkinson (ed.), Pathology of the Ovary, Fallopian Tube and Peritoneum, Essentials of Diagnostic Gynecological Pathology, DOI 10.1007/978-1-4471-2942-4_6, © Springer-Verlag London 2014

Introduction

This chapter aims to highlight the pros and cons of the use of a frozen section (FS) in the diagnosis of ovarian pathology at the time of surgery. Like all approaches, it is not perfect and does rely on a very close working relationship between the pathologist and surgeon to ensure

that when, and if, it is used the maximum patient benefi t is obtained. A FS (like all diagnostic pathology) will never be fully accurate. However, if one accepts its potential limitations, it can be a very good tool in the management of patients with suspected ovarian pathology. This chapter will aim to highlight major issues with the use of a FS service for ovarian diagnosis and will out-line potential pitfalls. It is not intended to be a textbook of FS ovarian pathology – the remain-der of this book describes in far greater detail the diagnostic criteria for ovarian pathology diagno-sis. These still apply even if based on FS mate-rial. A recent survey has shown that FS use in

P. A. Cross , B Med Sci, MBBS, FRCPath Department of Pathology , Queen Elizabeth Hospital , Sheriff Hill , Gateshead, Tyne and Wear NE9 6SX , UK e-mail: paul.cross@ghnt.nhs.uk

6 Frozen Section Use in the Diagnosis of Ovarian Pathology

Paul A. Cross

Abstract

This chapter aims to highlight the pros and cons of the use of a frozen section (FS) in the diagnosis of ovarian pathology at the time of surgery. Like all approaches, it is not perfect and does rely on a very close working relationship between the pathologist and surgeon to ensure that when, and if, it is used the maximum patient benefi t is obtained. A FS (like all diagnostic pathology) will never be fully accurate. However, if one accepts its potential limitations, it can be a very good tool in the management of patients with suspected ovarian pathology. This chapter will aim to highlight major issues with the use of a FS service for ovarian diagnosis and will outline potential pitfalls. It is not intended to be a textbook of FS ovarian pathology – the remainder of this book describes in far greater detail the diagnostic criteria for ovarian pathology diagnosis. These still apply even if based on FS material. A recent survey has shown that FS use in the UK, when performed, is largely done for ovarian/pelvic masses and lymph nodes in cervical cancer surgery.

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the UK, when performed, is largely done for ovarian/pelvic masses and lymph nodes in cervical cancer surgery [ 1 ].

Why Do a Frozen Section?

The management of ovarian pathology is impos-sible without tissue to make a diagnosis. The ova-ries can be the site of a vast range of pathologies, from benign to malignant, with the added prob-lem of borderline lesions, but can also be the pre-senting site of malignancy elsewhere as a secondary deposit(s). For this reason, the sur-geon/oncologist cannot base any rational treat-ment option until a defi nite diagnosis is arrived at, to both benign and malignant but also to pri-mary site (if possible). Given this, the ideal would be preoperative diagnosis, but this is not always possible. If there is a cytology sample (e.g., ascitic fl uid, FNA), then this may yield a diagno-sis (see Chap. 7 ). However, this can often be inconclusive or at worst misleading [ 2 ], and a histology sample will always remain the most likely sample to yield a defi nitive diagnosis. It is also important to decide in what circumstances a FS will be used at operation. Is it for diagnosis of malignancy (irrespective of stage), or is it only for cases of potential early-stage disease? One protocol can only do a FS for potential stage 1 or 2 disease, and hence a staging procedure may be required, as opposed to a higher-stage disease where debulking surgery rather than staging is performed. It can be argued that these later higher-stage cases are equally in need of diagno-sis. However, the surgical approach is very differ-ent between the two.

Often much liked by surgeons, a FS can be viewed with suspicion by pathologists. A FS can be stressful for all involved and does require guaranteed availability of laboratory staff and a pathologist. There is also a large difference between an occasional “one off” FS and a routine FS service as is used in some centers for intraop-erative ovarian diagnosis.

In clinical terms a FS offers the possibility of a one-stage operation, rather than the more usual biopsy-action fl ow (e.g., operate, take biopsy,

await report, and then reoperate some time later to perform defi nitive surgery). This is more akin to the “see and treat” vs. “see and biopsy” approach used in colposcopy in which gyneco-logical pathologists and surgeons are familiar with. The one-stage FS approach can reduce the need for a second operation and anesthetic, and their inherent potential risks, but only if the FS diagnosis is robust enough to ensure that correct surgery is undertaken with a high probability of success [ 2 , 3 ].

A FS can also allow for tissue taken at one hospital site to be remotely reported at another hospital site if the correct technology and skills are available [ 4 ]. This of course applies to all his-tology in principle, but given the need for rapid diagnosis, the expertise to report a FS (given its immediate patient management impact) does not have to be at the same site as the actual surgery.

Given that fresh tissue will be sent to the labo-ratory for the FS to be taken, a FS service also allows fresh tissue to be taken for research, given of course that the correct patient consent and research/ethics protocols are followed.

Ground Rules for FS Use

Before any FS is undertaken, both sides (surgeon and pathologist) must understand the use and issues with a FS. A FS will not always yield a defi nite diagnosis, but this should be relatively rare. Both sides should accept and understand this. It is imperative that an agreed protocol is decided upon before an ovarian FS is undertaken, particularly with respect to cases called border-line on FS. If a FS is not going to affect what pro-cedure the surgeon actually performs at that time, then a FS is not needed – this should go without saying but does need emphasizing!

In reporting terms a FS diagnosis has one of three outcomes: benign, malignant, or defer to paraffi n (relatively uncommon). Very few papers quote a “defer” rate, but rates of zero [ 5 ] to up to 6.3 % [ 6 ] are quoted in studies with reasonable numbers of cases. However, in ovarian pathology there is also the category of borderline (BL). This must be accounted for in any agreed protocol

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between pathologist and surgeon. This category is certainly not as robust a diagnosis as one of benign or malignant and the degree of inaccuracy does appear to depend largely on the size/weight and type of lesion [ 5 , 7 ] and to some extent on the experience of the reporting pathologist [ 8 ]. Our protocol places a BL lesion into the malignant category clinically and would evoke a staging procedure. However not all would agree and feel this could lead to unnecessary overstaging [ 9 ]. It must be clear how a BL diagnosis will be responded to in the clinical protocol. A diagnosis of “at least borderline” is perfectly acceptable in diffi cult BL/malignant cases [ 10 ] as it does aid the surgeon.

FS Booking/Transport

Given that nearly all cases of suspected malig-nancy will be discussed within the setting of an MDT preoperatively, cases where a FS may be of use can be identifi ed. This allows the surgeons to plan their operating lists and equally allows them to prewarn the laboratory of the need for a FS ideally at least 24 hours in advance. This allows the laboratory to ensure suffi cient staff-ing, including alerting the pathologist. How such a planned FS is dealt with and rostered within the laboratory will depend on each individual laboratory’s approach to how it works. It is vital to ensure a reporting pathologist is identifi ed. Given that a FS will only involve up to 5–10 min of a pathologist’s time (description/block taking/reporting), this should not be overly disruptive to the pathologist’s routine working pattern. Such prior booking also ensures that all staff involved with the specimen transfer (in particular porter-ing staff and lab reception staff) are alerted in advance.

If the FS is no longer required for any reason, it should also be self-evident that the surgical team should inform the laboratory so that they can be “stood down” for that FS.

It is obvious that a reliable cryostat is essential to the performance of a FS. Most laboratories within the UK will have one, but it is often infre-quently used. In the UK, FS use is not common,

whereas in other countries, e.g., the USA, it is far more used. Hence, in a UK laboratory the general experience of the FS process is far more limited, both at the technical and pathologist level. From the technical point of view, it may require prac-tice to ensure consistent, quality sections. This must cover not only the freezing/section stage but also hand staining.

How Long Does a FS Take?

Given that the patient is anesthetized, the time of a FS must not materially impact on patient safety in the operating room. One must factor in the total time for the FS process – from theater, trans-port to the laboratory, processing, and reporting. For FS overall, Novis and Zarbo [ 11 ] found that over 90 % of FS can be processed and reported back to the surgeon within 20 min of receipt within the laboratory. This is a target that is achievable. Mean times of 18.5 min, range 10–45 min, are reported [ 12 ], with the longer times usually refl ecting FS being taken on more than one ovary or site.

Communication of Results

Whenever a FS is performed, clear, concise, unambiguous communication is vital between the requesting surgeon and reporting pathologist. It should go without saying that the patient demo-graphics on the request form and specimen pot must be consistent with each other and easy to read. The request form must state why the FS is required and also any relevant clinical fi ndings or history. This should include operative fi ndings, but also any abnormal tumor markers. It must also include any relevant medical history, and in this context any previous history of malignancy is essential. It is amazing how often such a history appears to be forgotten about! Given the potential for secondary malignancy presenting as an ovar-ian mass, any history of prior malignancy is vital for the reporting pathologist. Such information may allow the pathologist to suggest that any malignancy may not be of ovarian origin and

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hence point the surgeon in another direction. However, it must also be remembered that this may be the fi rst presentation of an occult primary malignancy elsewhere, and in this context the separation (if possible) of a secondary malig-nancy from an ovarian primary can dramatically affect the surgeon’s approach.

It is also vital that the form indicates who the pathologist must contact to give the FS report. Invariably this will be by telephone. Very few (if any) operating theaters these days have the FS taken and processed within the theater suite, and most specimens are conveyed by portering staff to the pathology laboratory for processing. It is all too easy to waste 5–10 min ringing around to fi nd the correct operating theater or surgeon in order to give back a report!

Given that any FS is an urgent request, it must not be delayed in its transport or reporting. The use of a high visibility FS form, e.g., yellow/orange, can help ensure that LEAN visual man-agement principles are applied [ 13 ].

Health and Safety Aspects

A FS is a fresh unfi xed specimen and as such is a potential health risk to anyone who may come into direct contact with it. The specimen must be transported in compliance with appropriate guidance and is suitably identifi ed as a fresh specimen. Any standard operating procedure (SOP) must cover aspects of potential spillage/leakage, as well as handling for dissection

purposes to minimize any possible unnecessary exposure. If the patient is of potential high-risk category (e.g., hepatitis B positive, HIV posi-tive), then consideration should be given as to whether the FS could be avoided and routine his-tology performed to minimize any possible exposure risks.

Gross Description/Block Selection

The gross description of the FS sample is just as vital as the actual histological reporting. In gen-eral the FS will be a salpingo-oophorectomy but depending on the operative fi ndings may be an oophorectomy, an ovarian biopsy, or just a “pel-vic mass.” Occasionally a TAH/TLH with BSO may be received. Whatever specimen is received, the general principles of macroscopic description apply [ 14 ]. Particular note should be made of any defect/tear of any ovarian mass and as to whether it is intact or not and if any obvious tumor is seen on the ovarian surface or elsewhere. Weighing the intact ovarian mass is advised for future refer-ence. On section, mention must be made of the nature of the ovarian lesion, i.e., solid, cystic, or solid/cystic (Figs. 6.1 and 6.2 ). Is it obviously necrotic or congested/hemorrhagic? If cystic, is it uni- or multilocular? Do any cysts contain serous- type fl uid, mucin, blood (fresh or clotted), or a combination? Any obvious coloration may also point to a potential lesion (e.g., some sex cord- stromal hormone-producing lesions may have a yellowish tinge). A full description, however, can

a b

Fig. 6.1 Gross view of intact simple serous cyst ( a ) and of smooth, internal lining ( b )

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await until after proper fi xation and until routine blocks are taken.

For a FS any tissue taken must try to be repre-sentative of the lesion overall and be reported upon. Any necrotic areas must be avoided, as must any obviously calcifi ed foci, as they will not process for a FS. If the lesion is solid, blocks from apparently non-necrotic areas are advised. If cystic, then any fi rm/raised/locule intersections are recommended, as these appear more often as the site of any possible atypia if present. If purely cystic, then a “Swiss roll” approach can be used to maximize the amount of cyst wall tissue taken. If the whole lesion is apparently necrotic/infarcted (and invariably congested), then the least affected areas are advised. However, in the latter circumstances, one may anticipate that the FS may not be of diagnostic use.

How Many Blocks?

Any FS is a trade-off between obtaining a report that represents the ovarian lesion and getting the answer to the surgeon in a timely manner without compromising patient safety. In my experience, two blocks for a FS allows for this balance. Careful block selection (as outlined above) maxi-mizes the potential diagnostic yield. It also allows a backup section if for some reason the other is problematic to process or interpret. The use of two blocks allows a turnaround time of typically 15–20 min from receipt in the laboratory to report issue. This time is not wasted by the surgeon,

often allowing them to proceed with some of the operation that they need to perform (e.g., hyster-ectomy). More blocks can be taken if desired, but the time taken will be longer. It is likely that if more FS blocks are taken, the diagnostic accu-racy may improve, but there is no apparent evi-dence in the literature for this despite the intuitive nature of this statement. Less blocks may be quicker, but diagnostic accuracy again may be less with less material to review.

FS Appearance/Artifacts

Because the FS tissue is not processed through the usual histological process of dehydration/rehydration, a FS has a different, albeit similar, microscopic appearance to routinely processed histological material. While the architecture is essentially the same, the cellular detail is differ-ent, with larger nuclei and often more prominent nucleoli – i.e., less shrinkage artifact. Mitotic fi g-ures, whatever the nature of the lesion, are often more apparent than on routine material. Overinterpretation of what are routine FS changes must be avoided, and comparison with any recog-nizable benign tissue within the section should be taken to assess variation from the norm. Avoidance of any necrotic/infarcted areas is essential, as is overinterpretation of pyknosis/karyorrhexis. Hopefully careful block selection as outlined above will minimize this. There is also often an apparent multilayering of simple epithelium more so than is seen in routine

a b

Fig. 6.2 Gross view of simple mucinous cyst ( a ) and of multiloculated appearances on section ( b )

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processed sections. This is most likely due to the FS being thicker than the routinely processed sections, typically of the order of 6–7 um rather than the routine paraffi n-processed tissue section of some 3 um. The ability to see fi ne histological detail in a FS is also less, and more reliance on disorganized/abnormal architecture, malignant- type necrosis, nuclear pleomorphism, atypia, and abnormal/excessive mitotic activity are key, but are still easily recognizable. Specifi c issues with specifi c lesions will be dealt with later on.

Pathologists sometimes balk at reporting FS due to a lack of familiarity with the material and FS appearance. This is understandable, but expe-rience can easily be obtained. In the initial stages, samples can be sent fresh to the laboratory and FS material taken but not reported upon urgently. Pathologist experience and confi dence will soon develop if this is done. FS material from other centers can also be used to gain experience. Correlation of the FS slide with the routinely pro-cessed equivalent block is essential to educate the reporting pathologist to be able to better recog-nize features for future reporting.

How Good Is a FS?

There is a wealth of literature on the use of FS in the reporting of ovarian pathology. Many are small series, dealing with a general service, but many lack suffi cient detail to allow more in-depth analysis. Several reviews [ 6 , 15 , 16 ] highlight

studies that do allow meaningful data analysis, as do some of the larger single-site papers [ 5 , 12 ]. Heatley [ 15 ] makes the plea for papers detailing a FS service to include more detail on tumor types, but also a more detailed breakdown by report (benign, malignant, and also borderline) and also of clinical context/picture. Overall, the outcomes for a FS do vary by tumor type (includ-ing size and weight) and diagnostic category. Table 6.1 outlines overall values and suggests that ovarian FS can be an effective, accurate tool. One may ask what the equivalent values are for the “gold standard” of routinely processed histo-logical material, to which the FS is of course compared. FS reporting compares very favorably considering the limitations of less blocks and a more pressurized reporting situation.

How a FS is evaluated compared to the paraffi n- processed “gold standard” is also a moot point. While most would quote sensitivity and specifi city, values for positive predictive value (PPV) and negative predictive value (NPV) are quoted [ 15 ], as are values for pre- and post-test probability [ 12 ] as well as likelihood ratios [ 15 , 16 ]. These different approaches all show good operating values for ovarian FS. The poorest value in any of these approaches is with a borderline FS diagnosis. How the borderline cat-egory is grouped (with benign or malignant) also alters the overall values. Table 6.2 gives a fl avor of these other approaches.

The paper by Cross et al. [ 12 ] summarizes the overall data from their center as follows in

Table 6.1 Pooled typical literature values for sensitivity and specifi city for ovarian FS diagnosis by report category

Benign vs. BL/carcinoma Benign vs. BL Benign vs. carcinoma BL vs. carcinoma

Sensitivity (%)

Specifi city (%)

Sensitivity (%)

Specifi city (%)

Sensitivity (%)

Specifi city (%)

Sensitivity (%)

Specifi city (%)

Medeiros et al. a 99 88 99 66 94 99 91 95 Heatley a 98.7 89.9 98.9 70.8 99.7 95.8 93.6 93.1 Geomni et al. a 65–97 97–100 – – 71–100 99.3–100 – – Ilvan et al. b 100 94.9 100 86.8 100 97.2 100 88.9 Cross et al. b 98.6 91.2 99 72.3 99.6 95.6 98 83.5

Some values derived from values within papers BL borderline tumor a Literature review based on suitable papers (Medeiros et al., 14 papers, 3,659 women; Heatley 18 papers, 4,542 women; Geomoni et al., 18 papers, 4,387 women) b Large single-center studies (Cross et al., 1,342 women; Ilvan et al., 617 women)

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clinical terms: of the 1,342 women who had a total of 1,439 FS, 1,268 (94.5 %) women had the correct surgical procedure at the time the FS was reported; 58 (4.3 %) women were understaged, and 16 women (1.2 %) were overstaged based on the FS report. However, the actual effect of understaging may be clinically minimal [ 17 ].

The literature indicates that certain types of ovarian tumors are less accurately reported at FS than others. This applies in particular to muci-nous lesions [ 5 , 12 , 18 ]. These are invariably larger, heavier complex lesions than other epithe-lial lesions. The often focal nature of both border-line and malignant changes in mucinous tumors is also an issue. Current evidence also suggests that the majority of mucinous lesions of the ovary are not of primary ovarian origin, and hence any mucinous lesion should be considered potentially of metastatic origin [ 19 ], even if apparently of “obvious” benign appearance. Given this, any mucinous tumor should be considered potentially malignant and may require close surgical exami-nation of the bowel and appendix in particular.

The diagnosis of BL on an ovarian FS is less reliable than one of benign or malignant. The issue depends on how a BL lesion is classifi ed and hence the clinical action resulting from that diagnosis (staging or not). Accuracy (i.e., a BL diagnosis remaining as a BL diagnosis) is of the order of 50 % [ 12 , 16 ]. The majority of the incor-rect diagnoses uplift a BL diagnosis to one of malignancy; hence, a clinical approach which

places a BL diagnosis along with a malignant diagnosis is tenable and does not have a real clin-ical impact [ 17 ]. This does vary by epithelial sub-type and is least accurate with a mucinous lesion [ 12 , 18 , 20 , 21 ]. These papers, and the literature review ones, show that increasing tumor size (and weight) renders the BL diagnosis less robust. In this situation, a variation from 91.7 % accu-racy for small (<450 g) lesions to 66.7 % for larger (>1,360 g) lesions has been found [ 21 ]. The false-negative reporting rate (i.e., called BL but actually carcinoma) can vary 5.4-fold between serous BL and mucinous BL [ 12 ], refl ecting the greater diagnostic problems with a mucinous lesion.

Errors with FS diagnosis essentially are due to two causes: sampling errors or interpretational errors [ 12 ]. The former may refl ect poor block selection, but is intrinsic to the FS approach where only limited material is taken due to time constraints. Interpretational errors are also inher-ent to diagnostic pathology. Educational review of such cases by the reporting pathologist team can help reduce this, but this should be common practice in all cellular pathology departments to help reduce inaccurate diagnoses.

The overall outcome of FS reporting must be of suffi cient quality to allow the surgeon who is relying upon it to base their surgical action upon it. This information is also a necessity in ensuring that the patient herself has accurate information to make an informed decision for operative con-sent. This is vital, as effectively the woman does not know exactly what procedure she will be hav-ing before surgery, and hence she also must have an appreciation of how good (or bad) a FS can be upon which her exact surgery is going to be based. Each unit should produce its own data on this with suffi cient numbers and time, but ini-tially typical literature values can be used to help with these discussions.

Specifi c Diagnostic Challenges

The criteria for diagnosis in a FS are essentially no different to those of a paraffi n section, although the appearances are different from that

Table 6.2 Typical literature values for other statistical approaches at looking at FS diagnoses

Benign vs. carcinoma

Benign vs. BL

BL vs. carcinoma

PPV 97.9 (97.3–98.4)

94.9 (94.1–95.7)

77.7 (73.5–87.4)

NPV 99.5 (98.9–99.7)

92.3 (89–94.6)

98.2 (97.3–98.8)

LR+ 23.99 (18.52–31.1)

3.384 (2.94–3.89)

13.293 (10.94–16.15)

LR− 0.003 (0.01–0.006)

0.015 (0.01–0.022)

0.069 (0.047–0.103)

From Table 2 in Heatley [ 15 ] BL borderline, PPV positive predictive value, NPV nega-tive predictive value, LR positive likelihood ratio, LR negative likelihood ratio

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of the routinely processed material as outlined above. It is not intended to describe all the types of lesions or tumors that may be seen within an ovary, which are covered in more detail in the rest of this book. However, certain problematic areas will be outlined to help with FS diagnosis.

Benign Nonneoplastic Lesions

It must not be forgotten that an ovary (or ovaries) can appear clinically suspicious or even malig-nant without actually being so. The literature does not cover this aspect of ovarian FS well, being not surprisingly preoccupied with malig-nant diagnoses. Table 6.3 outlines the typical nonneoplastic diagnoses quoted at ovarian FS. Processes such as endometriosis (Fig. 6.3 ), salpingo-oophoritis, or physiological cysts can present as unilateral (or sometimes bilateral) masses, sometimes associated with torsion. The FS of viable areas will show typical features of

these processes, and critical evaluation of the lack of malignant features ought to allow correct diagnosis. Many ovarian endometriotic cysts may appear fi brotic, with evidence of old hemor-rhage, and the classic features of both benign endometriotic stroma and glands may not always be apparent.

Features of congestion and hemorrhagic infarction may be seen in any ovarian lesion – these appearances typify torsion – and inspection of viable areas (if any can be found) is essential to try and allow for diagnosis. The gross appear-ance is typically that of a markedly congested and necrotic mass, the nature (solid or cystic) of which will refl ect the underlying lesion. In many torted ovaries, however, residual viable tissue can be very problematic to fi nd and may not be iden-tifi ed even after extensive sampling for routine processing, and so FS material may not yield a fi rm diagnosis in this situation.

A hydrosalpinx may be mistaken for an ovar-ian cyst and submitted for FS as an ovarian/para- ovarian or tubo-ovarian cyst. It does not matter for the purposes of a FS as all are essentially those of a benign serous cyst, the exact origin of which can await more extensive sampling on rou-tine processing. Features such as the ovarian cor-tex or primordial follicles may help identify the ovary, but are not essential if no malignant fea-tures are seen.

Physiological cysts (e.g., follicular or luteal) (Fig. 6.4 ) are unilocular, smooth, and invariably

Table 6.3 Benign nonneoplastic diagnoses at ovarian FS

Nonneoplastic diagnosis

Cross et al. (11.6 % of all FS diagnoses)

Ilvan et al. (18.3 % of all FS diagnoses)

Endometriosis 112 71 Infl ammation/abscess 37 13 Normal ovarian cysts 18 27 Others 0 2 Total numbers 167 113

a b

Fig. 6.3 Frozen section appearance of benign endometriosis showing glands and stroma ( a F ×10), and at higher view ( b F ×40), note the bland glands and stroma and intimate association of the two

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solitary except under unusual circumstances (e.g., hyperstimulation, polycystic ovary syn-drome) but again show features of benign cysts. Exact classifi cation is not essential at a FS, but be aware that physiological cysts can show quite a high mitotic rate, and some luteal cysts can show some pleomorphism, but again the overall archi-tecture, and invariably history, will help in diagnosis.

Specifi c Problem Areas in Ovarian FS Diagnosis

Primary Ovarian Epithelial Lesions

The majority of ovarian lesions in adults sub-jected to a FS will be of epithelial origin. Many will be simple/benign cysts. These are not usu-ally problematic. For more detailed descriptions of ovarian pathology in general, the reader is advised to read the other chapters of this book. While this section will not cover every possible ovarian pathology, it will from experience try and highlight common problems.

Serous cysts are usually unilocular and smooth lined (Fig. 6.5 ). Serous cysts may have papillary areas on the internal aspect, but these can also be encountered on the capsular surface as exophytic ovarian lesions (Fig. 6.6 ). These papillary (or solid) areas, if present, are the ones best sampled. Borderline serous lesions may be architecturally

complex with multilayering and show some mild cytological atypia (Fig. 6.7 ). Such low-grade borderline areas and true micropapillary lesions may require careful scrutiny under the micro-scope, but the degree of architectural complexity seen together with the minor cytological changes is too marked for simple benign serous epithe-lium. High-grade serous borderline change is not problematic as marked nuclear atypia with epi-thelial stratifi cation and a high mitotic rate are present. These features usually accompany archi-tectural complexity (Fig. 6.8 ).

Mucinous lesions are usually multiloculated complex cysts with multiple cyst intersections and often solid areas (Fig. 6.2 ). Again, solid/cyst intersection areas are best sampled for FS. Any diagnosis of a mucinous lesion (even if appar-ently benign) (Fig. 6.9 ) may refl ect secondary spread [ 19 ]. If apparently benign this appears to be at low risk, especially if the lining is endocer-vical in type. If enteric and BL, then it is more diffi cult to be so certain (Fig. 6.10 ). Given this problem, an algorithm based on size and uni- or bilaterality of mucinous lesions [ 22 ] has been proposed to help classify malignant mucinous lesions as primary or secondary. In essence, this classifi es all bilateral mucinous carcinomas as metastatic, unilateral mucinous carcinomas <10 cm as metastatic, and unilateral mucinous carcinomas ≥10 cm as primary ovarian mucinous carcinomas and can correctly classify up to 90 % of neoplasms. However, while this may be of

a b

Fig. 6.4 Simple follicular cyst ( a FS × 10, b FS × 40). Note multilayering and variable nuclear size. An occasional mitosis may also be seen. However, note the simple cyst architecture, and no invasion is present

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assistance, it does require information on both ovaries (or both for FS evaluation) and also has an error rate. Others [ 23 , 24 ] have suggested amendments to this approach with varying degrees of success.

Secondary mucinous tumors are most com-monly of the large bowel (Fig. 6.11 ) or upper gastrointestinal tract, especially the stomach. One will often fi nd the typical features of “dirty necrosis” or signet ring forms with these two par-ticular sites, respectively, both of which can help identify and suggest secondary spread at FS. The appendix must also be considered as a potential primary site for mucinous lesions of the ovary. A FS which consists mostly (if not solely) of mucin

may represent an inspissated mucinous cyst, a mucinous adenocarcinoma, or a pseudomyxoma. In these circumstances if only mucin is seen at FS, then a diagnosis as such cannot be given. In these cases given the inherent lower accuracy of a FS in the presence of a mucinous lesion, a diag-nosis of borderline may be offered, and further surgery/staging may depend also on the overall clinical picture. If any epithelium is seen, this may point to one lesion or another and help with better classifi cation.

Endometrioid adenocarcinomas are easily confused at FS with high-grade serous carci-noma, and this can also occur on routinely pro-cessed material. In practical terms it is not a distinction that will matter, as both will appear malignant, and exact classifi cation can await routine slides. Clear cell carcinomas can be deceptively bland on FS (Fig. 6.12 ) – this may be due to the clear cytoplasm, but scrutiny of the nuclear features and overall architecture should help with diagnosis [ 25 ]. The distinction between primary and secondary clear cell lesions of the ovary is not possible on a FS. Carcinosarcomas can occur in the ovary but are invariably easily diagnosed as malignant given the typically high-grade malignant fea-tures, even if the actual mixed nature of the tumor is not recognized at FS.

Brenner (benign urothelial) tumors (Fig. 6.13 ) may present as tumors in their own right or be associated with mucinous tumors. Their typically irregular nests of cells may suggest malignancy

a b

Fig. 6.5 Simple serous cyst ( a frozen section ×40, b paraffi n section ×40). Note apparent multilayering on FS but lack of other atypical features, confi rmed on the PS

Fig. 6.6 Gross specimen exhibiting surface papillary areas, in keeping with serous surface proliferation. It is not possible to say if this is benign or not on gross inspection

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architecturally, but the typical urothelial nuclei with some nuclear grooves and lack of other malignant features should allow correct diagnosis. If necrosis, pleomorphism, or fre-

quent mitotic fi gures are present, then a border-line or frankly malignant diagnosis should be considered, but such malignant urothelial lesions are relatively rare.

a b

Fig. 6.7 Borderline serous lesion ( a FS ×10, b FS ×40). Note architectural complexity and multilayering and nuclear variability

a b

c d

Fig. 6.8 Necrotic/solid ovarian tumor ( a ) which could be many lesions but is a high-grade serous carcinoma of the ovary. ( b ) (FS ×10) and ( c ) (FS ×40) show marked pleo-

morphism and mitotic activity, as well as some psam-moma bodies in ( c ). PS of fi nal histology from same block ( d , ×40)

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Sex Cord-Stromal Lesions

The majority of sex cord-stromal tumors (SCST) will be benign, the most common being fi bro-

thecomas. These can be cystic with associated Brenner tumors, but display no malignant fea-tures. However, one must look to exclude second-ary tumors from the stomach (the classic

a b

Fig. 6.9 Simple mucinous cyst. ( a ) (FS ×20) and ( b ) (FS ×40) show bland mostly enteric glands, with no atypical cellular features although some complexity of the actual cyst lining is not unusual

a

c

b

Fig. 6.10 Borderline mucinous cyst (all FS, a ×10, b ×10, c ×40) showing marked atypia and complexity, but with no invasion seen

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Krukenberg tumor) or breast (especially lobular carcinoma) which can look grossly like a typical fi bro-thecoma.

Tumors such as granulosa cell lesions (Fig. 6.14 ) or Sertoli-Leydig tumors will display their typical histological features. Both tumors

a b

Fig. 6.11 FS of metastatic colonic adenocarcinoma ( a ×10, b ×40). Note high-grade nuclear features and typical (when present) “dirty-type” necrosis

a

c

b

Fig. 6.12 Clear cell carcinoma. ( a ) Gross specimen with no obvious differentiating features from other malignant tumors. ( b ) (FS ×20) and ( c ) (FS ×40) show architectur-

ally complex clear cells with markedly variable nuclei, but with very few mitoses typically. Focal necrosis is also present

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may display a wide range of appearances, but again the overall features make recognition of a non-benign process usually straightforward. A granulosa cell tumor may exhibit a yellow appearance to the naked eye, and while not diag-nostic this may suggest a steroid-producing lesion.

A FS will not always allow exact classifi cation as to the tumor type, but this is to be expected. The function of a FS is to assist the surgeon, and as such recognition of a non-benign process is key.

Germ Cell Lesions

The most common germ cell tumor (GCT) is the mature cystic teratoma (dermoid cyst). As such

its gross appearance is diagnostic with a typical greasy hair ball centrally. Malignant change is uncommon and can be of epithelial origin (typi-cally a squamous cell carcinoma) but can occur in any of the germ cell layers present. As such, sampling of solid/suspicious areas is advocated for FS, but one must be prepared to consider vir-tually any diagnosis possible. Monodermal tera-tomas (e.g., struma ovarii) can be more tricky (Fig. 6.15 ), but again are invariably associated with more typical teratomatous areas, but these may be lacking in a true monodermal teratoma. Secondary thyroid tumors to the ovary are rare.

Tumors such as dysgerminoma or embryonal carcinoma are straightforward on FS given their typical features.

Pediatric Ovarian FS

The range and type of possible ovarian pathol-ogy, both benign and malignant, are very differ-ent in the pediatric age range. No tumor has an absolute age predilection, but one must consider a potentially different range of tumors in the young. However, the approach to surgery is typi-cally far more conservative in children, and diag-nosis will usually rest on routinely processed material rather than on a FS diagnosis. As such, a routine FS approach to pediatric pathology in general appears more limited, which is supported

a b

Fig. 6.13 Benign Brenner tumor ( a FS ×10, b FS ×40). Some complex-appearing glands set in a fi brous stroma may at fi rst glance appear alarming, but typical urothelial

cells and nuclei and lack of other atypical features allow a correct diagnosis

Fig. 6.14 Gross specimen of adult granulosa cell tumor

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by a dearth of such literature on this topic [ 26 ], but it does highlight a relatively high error and defer rate.

Secondary Tumors to the Ovary

One of the questions that should be asked at every ovarian FS is “is the lesion seen primary ovarian or secondary to the ovary?” In the vast majority of times, it will be the former. However, as has been highlighted earlier, any mucinous lesion may be secondary. Tumors with a signet ring appearance are likely to be metastatic (possibly from the stomach or appendix), while ones with a neuroendocrine (carcinoid, well-differentiated

neuroendocrine carcinoma) appearance can be primary or secondary. Colonic carcinoma has a typical histological appearance of overtly malig-nant adenocarcinoma with “dirty necrosis” which is not usually seen in other tumors (Fig. 6.11 ). Lobular carcinoma will have its typical appear-ance (Fig. 6.16 ), but may be diffi cult to spot (as may be signet ring cells) if scanty and set within a fi brous stroma. In many cases, however, identi-fi cation as a secondary tumor may not be possible on a FS. Given that colonic carcinoma appears to be the most common tumor to spread to the ova-ries, in many cases this can be identifi ed. In one study, secondary tumors formed 4.8 % of ovarian tumors at FS, of which the largest single group were of gastrointestinal/appendiceal origin (57

a b

Fig. 6.15 Monodermal teratoma – struma ovarii (FS, a ×10 and b ×40). Note well-defi ned follicles with mostly single cell layers, with plentiful eosinophilic material (colloid)

a b

Fig. 6.16 Metastatic lobular carcinoma to ovary ( a FS ×40, b PS ×40). Note typical lobular Indian fi le arrangement and occasional intracytoplasmic lumen in some cells

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out of 69) and overall 77 % were reported at FS as most likely of metastatic origin [ 12 ]. Such information, if it can be diagnosed, is of use allowing the surgeon to look for a primary site elsewhere and hence potentially adjust the surgi-cal approach accordingly.

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