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tumor was centred in the renal medulla. Microscopic features were very similar in the 2 cases; the tumors were well-demar- cated, white-gray colored, and without capsule. The tumor cells were predominantly cuboidal, with a slight eosinophilic or clear cytoplasm. Nuclei were round without prominent nucleoli. Mitotic figures were rare. No necrosis was noted. The tumor cells were arranged mainly in elongated and interconnecting tubules (Fig 1). Sometimes, small sheets of spindle cells with minimal pleomorphism were also observed. No true papillae or cribriform structures were seen. The stroma was poorly cellular and often myxoid with plasma cells and mast cells. Alcian blue and periodic acid-Schiff stains were positive. Immunohistochemical study showed a diffuse positivity for pancytokeratin, vimentin, and E-cadherin. A focal expres- sion of cytokeratin 7, epithelial membrane antigen, and high molecular weight cytokeratin was observed. CD15, ACE, and Ulex were negative. The MIB-1 labeling index was very low (1%). The patients are healthy without evidence of disease respectively at three and seven years after surgery. We think that these 2 cases are very similar to those described by Parwani et al 1 under the term “low-grade myxoid renal epithelial neoplasms with distal nephron differentia- tion.” In agreement with Parwani et al, 1 we think that these tumors share morphologic similarities with those described as low-grade collecting duct carcinomas by MacLennan et al. 2 However, these tumors had a different immunohistochemical profile (Ulex/EMA). Interestingly, like those of Parwani et al, 1 our 2 patients were adult females bearing a tumor limited to the kidney with a benign clinical course. Thus we think that these tumors may represent a distinct clinicopath- ologic entity. XAVIER LEROY, MD SEBASTIEN AUBERT, MD BERNARD GOSSELIN, MD Department of Pathology Lille University Hospital Lille, France 1. Parwani AV, Husain AN, Epstein JI, et al: Low-grade myxoid renal epithelial neoplasms with distal nephron differentiation. HUM PATHOL. 32:506-512, 2001 2. MacLennan G, Farrow GM, Bostwick DG: Low-grade collect- ing duct of the kidney: Report of 13 cases of low-grade mucinous tubulocystic renal carcinoma of possible collecting duct origin. Urol- ogy 50:679-684, 1997 doi:10.1053/hupa.2002.124010 Reply To the Editor:—We thank Dr. Leroy and colleagues for their comments. Based on the clinical and histopathologic features that they describe, we agree that their 2 cases are likely additional examples of the entity that we have de- scribed. 1 We believe that these unusual renal tumors were described first as a subset of cases reported by MacLennan et al 2 as “low-grade collecting duct carcinomas” (specifically, cases represented in Figs 5 and 6), and in abstract form by Srigley et al 3 as “unusual renal carcinoma (RCC) with prom- inent spindle cell change possibly related to the loop of Henle.” The distinctive clinicopathologic features of this en- tity include (1) female predominance, (2) circumscription and frequent renal medullary epicenter, (3) interconnecting tubular and spindled architecture within myxoid stroma, (4) low-grade nuclei and eosinophilic cytoplasm, (5) ultrastruc- tural features consistent with distal nephron origin (collect- ing duct or loop of Henle), and (6) benign or indolent clinical course. Published immunohistochemical profiles of this tumor have been somewhat variable, with cytokeratin 7 and epithelial membrane antigen labeling most consistently. High molecular weight cytokeratin and Ulex labeling has been reported in some, but not all, cases. One of the strengths of the new 1997 classification of renal cell carcinoma 4,5 is that most of the accepted entities are associated with a distinctive genetic profile. Along these lines, we are greatly encouraged that comparative genomic hybrid- ization studies of these unusual renal tumors have recently been reported in abstract form. First, Rakozy et al 6 showed consistent losses of chromosomes 1, 4, 6, 8, 9, 13, 14, and 15 in a series of 5 tumors. Subsequently, Srigley et al 7 demon- strated frequent losses of chromosomes 1, 4q, 6, 8p, 9p, 11q, 13, 14, and 15 and gains on chromosomes 11q, 12q, 16q, 17, and 20q in a series of 10 tumors studied. Taken together, losses of chromosome 1, 6, 13, 14, and 15 are common to each of these studies. We hope that these studies represent the first steps toward elucidating the molecular pathogenesis of this interesting and distinctive clinicopathologic entity. ANIL V. PARWANI, MD PHD JONATHAN I. EPSTEIN, MD PEDRAM ARGANI, MD Department of Pathology The Johns Hopkins Hospital Baltimore, MD 1. Parwani AV, Husain AN, Epstein JI, et al: Low-grade myxoid renal epithelial neoplasms with distal nephron differentiation. HUM PATHOL 32:506-512, 2001 FIGURE 1. Interconnecting elongated tubules in a myxoid stroma. (Hematoxylin and eosin and saffron; original magnifi- cation 100.) 575
Transcript of Reply
tumor was centred in the renal medulla. Microscopic featureswere very similar in the 2 cases; the tumors were well-demar-cated, white-gray colored, and without capsule. The tumorcells were predominantly cuboidal, with a slight eosinophilicor clear cytoplasm. Nuclei were round without prominentnucleoli. Mitotic figures were rare. No necrosis was noted.The tumor cells were arranged mainly in elongated andinterconnecting tubules (Fig 1). Sometimes, small sheets ofspindle cells with minimal pleomorphism were also observed.No true papillae or cribriform structures were seen. Thestroma was poorly cellular and often myxoid with plasma cellsand mast cells. Alcian blue and periodic acid-Schiff stainswere positive.
Immunohistochemical study showed a diffuse positivityfor pancytokeratin, vimentin, and E-cadherin. A focal expres-sion of cytokeratin 7, epithelial membrane antigen, and highmolecular weight cytokeratin was observed. CD15, ACE, andUlex were negative. The MIB-1 labeling index was very low(�1%). The patients are healthy without evidence of diseaserespectively at three and seven years after surgery.
We think that these 2 cases are very similar to thosedescribed by Parwani et al1 under the term “low-grade myxoidrenal epithelial neoplasms with distal nephron differentia-tion.” In agreement with Parwani et al,1 we think that thesetumors share morphologic similarities with those described aslow-grade collecting duct carcinomas by MacLennan et al.2However, these tumors had a different immunohistochemicalprofile (Ulex�/EMA�). Interestingly, like those of Parwaniet al,1 our 2 patients were adult females bearing a tumorlimited to the kidney with a benign clinical course. Thus wethink that these tumors may represent a distinct clinicopath-ologic entity.
XAVIER LEROY, MDSEBASTIEN AUBERT, MDBERNARD GOSSELIN, MD
Department ofPathologyLille UniversityHospitalLille, France
1. Parwani AV, Husain AN, Epstein JI, et al: Low-grade myxoidrenal epithelial neoplasms with distal nephron differentiation. HUM
PATHOL. 32:506-512, 20012. MacLennan G, Farrow GM, Bostwick DG: Low-grade collect-
ing duct of the kidney: Report of 13 cases of low-grade mucinoustubulocystic renal carcinoma of possible collecting duct origin. Urol-ogy 50:679-684, 1997
doi:10.1053/hupa.2002.124010
Reply
To the Editor:—We thank Dr. Leroy and colleagues fortheir comments. Based on the clinical and histopathologicfeatures that they describe, we agree that their 2 cases arelikely additional examples of the entity that we have de-scribed.1 We believe that these unusual renal tumors weredescribed first as a subset of cases reported by MacLennan etal2 as “low-grade collecting duct carcinomas” (specifically,cases represented in Figs 5 and 6), and in abstract form bySrigley et al3 as “unusual renal carcinoma (RCC) with prom-inent spindle cell change possibly related to the loop ofHenle.” The distinctive clinicopathologic features of this en-tity include (1) female predominance, (2) circumscriptionand frequent renal medullary epicenter, (3) interconnectingtubular and spindled architecture within myxoid stroma, (4)low-grade nuclei and eosinophilic cytoplasm, (5) ultrastruc-tural features consistent with distal nephron origin (collect-ing duct or loop of Henle), and (6) benign or indolentclinical course. Published immunohistochemical profiles ofthis tumor have been somewhat variable, with cytokeratin 7and epithelial membrane antigen labeling most consistently.High molecular weight cytokeratin and Ulex labeling hasbeen reported in some, but not all, cases.
One of the strengths of the new 1997 classification ofrenal cell carcinoma4,5 is that most of the accepted entities areassociated with a distinctive genetic profile. Along these lines,we are greatly encouraged that comparative genomic hybrid-ization studies of these unusual renal tumors have recentlybeen reported in abstract form. First, Rakozy et al6 showedconsistent losses of chromosomes 1, 4, 6, 8, 9, 13, 14, and 15in a series of 5 tumors. Subsequently, Srigley et al7 demon-strated frequent losses of chromosomes 1, 4q, 6, 8p, 9p, 11q,13, 14, and 15 and gains on chromosomes 11q, 12q, 16q, 17,and 20q in a series of 10 tumors studied. Taken together,losses of chromosome 1, 6, 13, 14, and 15 are common toeach of these studies. We hope that these studies representthe first steps toward elucidating the molecular pathogenesisof this interesting and distinctive clinicopathologic entity.
ANIL V. PARWANI, MD PHDJONATHAN I. EPSTEIN, MDPEDRAM ARGANI, MDDepartment of PathologyThe Johns Hopkins HospitalBaltimore, MD
1. Parwani AV, Husain AN, Epstein JI, et al: Low-grade myxoidrenal epithelial neoplasms with distal nephron differentiation. HUM
PATHOL 32:506-512, 2001
FIGURE 1. Interconnecting elongated tubules in a myxoidstroma. (Hematoxylin and eosin and saffron; original magnifi-cation �100.)
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2. MacLennan G, Farrow GM, Bostwick DG: Low-grade collect-ing duct carcinoma of the kidney: Report of 13 cases of low-grademucinous tubulocystic renal carcinoma of possible collecting ductorigin. Urology 50:679-684, 1997
3. Srigley JR, Eble JN, Grignon DJ et al: Unusual renal cellcarcinoma (RCC) with prominent spindle cell change possibly re-lated to the loop of Henle. Mod Pathol 12:107A, 1999
4. Kovacs G, Akhtar M, Beckwith JB, et al: The Heidelbergclassification of renal cell tumors. J Pathol 183:131-133, 1997
5. Storkel S, Eble JN, Adlakha K, et al: Classification of renal cellcarcinoma. Cancer 80:987-989, 1997
6. Rakozy C, Schmahl G, Storkel S: Tubulo-mucinous renal neo-plasms show consistent morphologic, immunohistochemical, and ge-netic findings: Is it time to define a new renal tumor entity? ModPathol 14:190A, 2001
7. Srigley J, Kapusta L, Reuter V, et al: Phenotypic, molecular,and ultrastructural studies of a novel low grade renal epithelialneoplasm possibly related to the loop of Henle. Mod Pathol 15:182A,2002
doi:10.1053/hupa.2002.124011
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