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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