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An approach to microscopic interpretation

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This document provides an introduction to microscopic interpretation in dermatopathology. It outlines the steps to examine a histopathology slide which include: examining the slide with the naked eye to gain initial clues, scanning at low magnification to identify the type of specimen and site of involvement, and examining at higher magnifications to confirm features and identify specific cell types. It then describes the normal histology of skin, identification of common cell types found in skin such as keratinocytes, melanocytes and fibroblasts. Finally, it discusses methods of diagnosis including pattern recognition and algorithms to categorize inflammatory dermatopathology patterns.

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Introduction to microscopic interpretationDr. Santosh Rathod
Have your eyes and mind openProcessing the acquired visual informationArriving at a tentative diagnosis (ie, model building)Testing the preliminary diagnosis with further examinationConfirming the diagnosisCorrelating available clinical information Finalizing the diagnosis
From where to start?
Examination of the 際際滷 with the Naked EyeTo gain some appreciation of the size, number, and nature of the histologic sections on the slideThe 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) MagnificationFirstly, one should attempt to identify the type of specimen submittedThen, 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 non-inflammatory.
Examination at IntermediateMagnificationThe 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 processesFor identification of specific cell types, such as lymphocytes or granulocytes
Normal histology of skinSt. CorneumSt. GranulosumSt. SpinosumSt. BasalePappilary dermisReticular Dermis
Identification of cellsType of cells normally present in epidermis :Majority are - Keratinocytes (90%)Minority population of Langerhans cellsMelanocytesNeuroendocrine(Merkel Cells)Unmyelinated axonsOccasional Cells Toker cells found in nipple epidermis in approximately 10% individuals
sGranular keratinocyteSpinouskeratinocyteBasal keratinocyte
Langerhans cellsMarrow derivedDendriticAntigen presenting cellsIn H&E sections, appear as clear cellsSpecial stains are generally required for their detection and enumeration
melanocyteMelanin synthesizing dendritic cellsLocated within basal layer of epidermis, hair bulb, ORSIn H&E stained section, dendritis are not visible, cell bodies can be seen dispersed in basal layerContain round to oval, dark stained nuclei that are generally smaller than basal keratinocyte
DermisCellular content : Fibroblasts Dermal dendritic cells Macrophages Mast cellsExtra-cellular content : Collagen Elastic fibres Ground substance
Dermal fibroblastAppear as inconspicuous bipolar spindle cells with elongated ovoid nucleiCant be reliable distinguished from other dermal spindle shaped and dendritic cells ( dermal dendrocytes)Synthesizes collagenIH stain Vimentin
Phagocytic macrophagesAlso, called HistiocytesAre of bone marrow origin, circulate in blood as precursors and enter tissue as monocytesActivated monocytes macrophagesAggregation of activated macrophages granulomasMacrophages that have ingested melanin- melanophagesMacrophages 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 cellsNeutrophilic granulocytesEosinophilic granulocytesBasophilic granulocytesLymphocytesPlasma cell
Neutrophilic granulocytePolymorphonuclearleucocyteLobated pop-corn shaped nuclei within pale pink fairly granular cytoplasmNuclear breakdown due to local necrosis or by autodigestion of nuclear lobes as in vasculitis results in nuclear dust of vasculitis
Eosinophilic granulocyteCharacterized by strongly eosinophilic granules in cytoplasm and a characteristically bilobed nucleiAlthough visible with routine stains, these granules stand out more clearly in brilliant red when stained with giemsa
Plasma cellHave abundant cytoplasm that is deeply basophilic, homogenous and sharply definedRound eccentrically placed nuclei along its membrane it shows course, deeply basophilic, regularly distributed chromatin particles which gives cart-wheel appearance
Methods of diagnosis in dermatopathogyInitial stage of pattern - by the process of hypothesis recognition by a gestalt generation and differ- based or instant recognition tial diagnosisPattern recognition method by Ackerman
Inflammatory Dermatopathology by Pattern and AlgorithmSteps Categorize the patternAssess the inflammatory cell populationLook for specific findings that direct the algorithm as far as it can be takenCorrelate the histologic assessment with known clinical information
Superficial PerivascularDermatitisSuperficial and Deep Perivascular DermatitisNodular and Diffuse DermatitisPanniculitisVasculitisFolliculitisand PerifolliculitisIntraepidermalVesicular and Pustular DermatitisSubepidermal Vesicular Dermatitis
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An approach to microscopic interpretation

  • 1. Introduction to microscopic interpretationDr. Santosh Rathod
  • 2. Have your eyes and mind openProcessing the acquired visual informationArriving at a tentative diagnosis (ie, model building)Testing the preliminary diagnosis with further examinationConfirming the diagnosisCorrelating available clinical information Finalizing the diagnosis
  • 4. Examination of the 際際滷 with the Naked EyeTo gain some appreciation of the size, number, and nature of the histologic sections on the slideThe 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.
  • 5. Examination of the MicroslideatScanning(2 X or 4X) MagnificationFirstly, one should attempt to identify the type of specimen submittedThen, 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 non-inflammatory.
  • 6. Examination at IntermediateMagnificationThe 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 processesFor identification of specific cell types, such as lymphocytes or granulocytes
  • 7. Normal histology of skinSt. CorneumSt. GranulosumSt. SpinosumSt. BasalePappilary dermisReticular Dermis
  • 8. Identification of cellsType of cells normally present in epidermis :Majority are - Keratinocytes (90%)Minority population of Langerhans cellsMelanocytesNeuroendocrine(Merkel Cells)Unmyelinated axonsOccasional Cells Toker cells found in nipple epidermis in approximately 10% individuals
  • 10. Langerhans cellsMarrow derivedDendriticAntigen presenting cellsIn H&E sections, appear as clear cellsSpecial stains are generally required for their detection and enumeration
  • 11. melanocyteMelanin synthesizing dendritic cellsLocated within basal layer of epidermis, hair bulb, ORSIn H&E stained section, dendritis are not visible, cell bodies can be seen dispersed in basal layerContain round to oval, dark stained nuclei that are generally smaller than basal keratinocyte
  • 12. DermisCellular content : Fibroblasts Dermal dendritic cells Macrophages Mast cellsExtra-cellular content : Collagen Elastic fibres Ground substance
  • 13. Dermal fibroblastAppear as inconspicuous bipolar spindle cells with elongated ovoid nucleiCant be reliable distinguished from other dermal spindle shaped and dendritic cells ( dermal dendrocytes)Synthesizes collagenIH stain Vimentin
  • 14. Phagocytic macrophagesAlso, called HistiocytesAre of bone marrow origin, circulate in blood as precursors and enter tissue as monocytesActivated monocytes macrophagesAggregation of activated macrophages granulomasMacrophages that have ingested melanin- melanophagesMacrophages that have ingested hemosiderin - siderophages
  • 15. Monocytes are indistinguishable by routine histology from lymphocytes as both have a small, dark, rounded nuclei with very scanty cytoplasm
  • 16. Macrophages are larger cells than monocyte and possess a vesicular, light staining, elongated nuclei with a clearly visible nuclear membrane
  • 17. Emigrant inflammatory cellsNeutrophilic granulocytesEosinophilic granulocytesBasophilic granulocytesLymphocytesPlasma cell
  • 18. Neutrophilic granulocytePolymorphonuclearleucocyteLobated pop-corn shaped nuclei within pale pink fairly granular cytoplasmNuclear breakdown due to local necrosis or by autodigestion of nuclear lobes as in vasculitis results in nuclear dust of vasculitis
  • 19. Eosinophilic granulocyteCharacterized by strongly eosinophilic granules in cytoplasm and a characteristically bilobed nucleiAlthough visible with routine stains, these granules stand out more clearly in brilliant red when stained with giemsa
  • 20. Plasma cellHave abundant cytoplasm that is deeply basophilic, homogenous and sharply definedRound eccentrically placed nuclei along its membrane it shows course, deeply basophilic, regularly distributed chromatin particles which gives cart-wheel appearance
  • 21. Methods of diagnosis in dermatopathogyInitial stage of pattern - by the process of hypothesis recognition by a gestalt generation and differ- based or instant recognition tial diagnosisPattern recognition method by Ackerman
  • 22. Inflammatory Dermatopathology by Pattern and AlgorithmSteps Categorize the patternAssess the inflammatory cell populationLook for specific findings that direct the algorithm as far as it can be takenCorrelate the histologic assessment with known clinical information
  • 23. Superficial PerivascularDermatitisSuperficial and Deep Perivascular DermatitisNodular and Diffuse DermatitisPanniculitisVasculitisFolliculitisand PerifolliculitisIntraepidermalVesicular and Pustular DermatitisSubepidermal Vesicular Dermatitis