Introduction to

microscopic

interpretation

Dr. Santosh Rathod

Have your eyes and mind

open

Processing the acquired visual information

Arriving at a tentative diagnosis (ie, model building)

Testing the preliminary diagnosis with further

examination

Confirming the diagnosis

Correlating available clinical information

Finalizing the diagnosis

From where to start?

While viewing slide one should proceed as following :

Initial Examination of the Slide

with the Naked Eye

Examination of the Microslide at

Scanning (2X or 4X) Magnification

Examination at Intermediate

Magnification

Examination at High Magnification

Examination of the Slide

with the Naked Eye To gain some appreciation of the size, number, and

nature of the histologic sections on the slide

The tinctorial properties (histochemical staining) also may provide clues to diagnosis;

For example,bluish cellular aggregates or nodules suggest high nuclear-to-cytoplasmic ratios because of basophilic staining of nuclei and, as a result of processes such as basal cell carcinoma, small cell carcinoma, and infil- trates of small lymphocytes or calcium deposition.

Examination of the MicroslideatScanning

(2 X or 4X) Magnification

Firstly, one should attempt to identify the type of specimen submitted

Then, inspect the specimen with the idea of determining in general

terms from what anatomic site the tissue was taken.

Entire specimen (ie, epidermis, dermis, or subcutis) should be

scanned

- for the principal site of involvement by a disease process, if

any, and

- the nature of the process, whether inflammatory

proliferative,

inflammatory and proliferative

or

Examination at Intermediate

Magnification

The tendency to go to higher magnification too soon

should be resisted because one often will overlook a

crucial feature, and thus, in effect, one “cannot see

the forest for the trees.”

The reasons for closer inspection of the specimen

(with 10Xand 40X objectives) are to confirm particular

features of pathologic processes

For identification of specific cell types, such as

lymphocytes or granulocytes

Normal histology of skin

St. Corneum

St. Granulosum

St. Spinosum

St. Basale

Pappilary dermis

Reticular Dermis

Identification of cells

Type of cells normally present in epidermis :

Majority are - Keratinocytes (90%)

Minority population of – Langerhans cells

Melanocytes

Neuroendocrine(Merkel Cells)

Unmyelinated axons

Occasional Cells – Toker cells found in nipple epidermis in

approximately 10% individuals

s

Basal keratinocyte

Spinouskeratinoc

yte

Granular

keratinocyte

Langerhans cells

Marrow derived

Dendritic

Antigen presenting cells

In H&E sections, appear as clear

cells

Special stains are generally

required for their detection and

enumeration

melanocyte

Melanin synthesizing dendriticcells

Located within basal layer of epidermis, hair bulb, ORS

In H&E stained section, dendritisare not visible, cell bodies can be

seen dispersed in basal layer

Contain round to oval, dark stained nuclei that are generally smaller

than basal keratinocyte

Dermis

Cellular content :

Fibroblasts

Dermal dendritic cells

Macrophages

Mast cells

Extra-cellular content :

Collagen

Elastic fibres

Ground substance

Dermal fibroblast

Appear as inconspicuous bipolar spindle cells with elongated ovoid

nuclei

Can’t be reliable distinguished from other dermal spindle shaped and

dendritic cells ( dermal dendrocytes)

Synthesizes collagen

IH stain – Vimentin

Phagocytic macrophages

Also, called Histiocytes

Are of bone marrow origin, circulate in blood as precursors and enter tissue as monocytes

Activated monocytes – macrophages

Aggregation of activated macrophages – granulomas

Macrophages that have ingested melanin-melanophages

Macrophages that have ingested hemosiderin -siderophages

Monocytes are indistinguishable by routine

histology from lymphocytes as both have a

small, dark, rounded nuclei with very scanty

cytoplasm

Macrophages are larger cells than monocyte and

possess a vesicular, light staining, elongated nuclei

with a clearly visible nuclear membrane

Emigrant

inflammatory

cells

Neutrophilic granulocytes

Eosinophilic granulocytes

Basophilic granulocytes

Lymphocytes

Plasma cell

Neutrophilic

granulocyte

Polymorphonuclearleucocyte

Lobated “pop-corn” shaped nuclei within pale pink fairly granular

cytoplasm

Nuclear breakdown due to local necrosis or by autodigestion of nuclear lobes as in vasculitis

results in “nuclear dust” of vasculitis

Eosinophilic

granulocyte

Characterized by strongly

eosinophilic granules in cytoplasm

and a characteristically bilobed

nuclei

Although visible with routine

stains, these granules stand out

more clearly in brilliant red when

stained with giemsa

Plasma cell

Have abundant cytoplasm that is

deeply basophilic, homogenous

and sharply defined

Round eccentrically placed nuclei

along its membrane it shows

course, deeply

basophilic, regularly distributed

chromatin particles which gives

“cart-wheel” appearance

Methods of diagnosis in

dermatopathogy

Initial stage of pattern - by the process of

hypothesis

recognition by a “gestalt” generation and differ-

based or instant recognition tial diagnosis

Pattern recognition

method by Ackerman

Inflammatory Dermatopathology by Pattern

and Algorithm

Steps

Categorize the pattern

Assess the inflammatory cell population

Look for specific findings that direct the algorithm as

far as it can be taken

Correlate the histologic assessment with known

clinical information

Superficial PerivascularDermatitis

Superficial and Deep Perivascular Dermatitis

Nodular and Diffuse Dermatitis

Panniculitis

Vasculitis

Folliculitisand Perifolliculitis

IntraepidermalVesicular and Pustular Dermatitis

Subepidermal Vesicular Dermatitis