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Skin tumours pathology


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Skin tumours pathology

  1. 1. Normal Skin Histology  Stratum Corneum  Stratum Lucidum  Stratum Granulosum  Stratum Spinosum  Stratum Basale 3
  2. 2.  Stratum basale/germinativum (“basal or “forming” layer)  One layer thick mitotic cells  10-25% melanocytes with processes into next layer  Merkel cells with sensory neurons  Stratum spinosum (“prickly” layer)  Cells appear spiny due to numerous desmosomes  Many Langerhans cells  Stratum granulosum (“grainy” layer)  Cells flatten  Organelles/nuclei begin to disintegrate  Keratin precursor granules begin to form  Stratum corneum + Lucidum(“horny” layer)  Cells are dead—too far from underlying capillaries to live  20-30 cells thick up to ¾ of dermal thickness
  3. 3. Definitions  Hyperkeratosis  Thickening of the stratum corneum, often associated with a qualitative abnormality of the keratin.  Parakeratosis  Modes of keratinization characterized by the retention of the nuclei in the stratum corneum.  Dyskeratosis  Abnormal keratinization occurring prematurely within individual cells or groups of cells below the stratum granulosum
  4. 4.  Acanthosis  Diffuse epidermal hyperplasia  Acantholysis  Loss of intercellular connections resulting in loss of cohesion between keratinocytes.
  5. 5. keratocanthoma Dome-shaped nodule with central keratin plug; 1-5 cm. diameter Cup-shaped lesion with central crater of keratin; downward pushing rounded border Higher power keratoacanthomalarge, glassy squamous cells with islands of eosinophilic keratin.
  6. 6. Actinic keratosis Nuclear abnormalities in basal keratinocytes; dysplasia does not involve full thickness of epidermis.
  7. 7. Histology - SCC  Irregular masses of epidermal cells proliferating into dermis  Keratinization in well-differentiated tumors  Range in degree of anaplasia
  8. 8. In Situ SCC  In situ SCC-type II (moderate) with atypical keratinocytes extending to the lower two thirds of the epidermis
  9. 9. In situ SCC  In situ SCC-type III (severe) with atypical  keratinocytes extending more than two thirds to full thickness  of the epidermis
  10. 10. SCC Irregular tongues of dysplastic squamous epithelium invading the dermis Epithelial cells exhibit glassy eosinophilic cytoplasm. Dyskeratotic cells, parakeratosis and horn pearl formation are also observed.
  11. 11.  Verrucous  Minimal atypia  Individual cell keratinization
  12. 12.  Spindle-Pleomorphic  Anaplastic  Little keratinization
  13. 13.  Adenoid Squamous  Anaplasia  Acantholysis  Tubular &adenoid appearance
  14. 14. Basal Cell Carcinoma HISTOLOGY •Large oval nuclei with little cytoplasm •Nuclei are uniform •Connective tissue stroma causes palisading  Nests of basaloid cells within the dermis
  15. 15.  Histologic Subtypes  Solid  Cystic  Adenoid  Keratotic (Basosquamous)
  16. 16.  Solid – no cellular differentiation  Cystic Differentiation towards sebaceous glands Cystic spaces within tumor lobules
  17. 17. Adenoid variety Glandular pattern
  18. 18.  Baso Squamous  Shows feature of both basal cell and squamous cell carcinomas  More aggressive clinically  Undifferentiated cells in combination with parakeratotic cells and horn cysts
  19. 19. Evolution of dysplastic nevus into malignant melanoma over time (not inevitable, but the potential always exists) Lentigo Junctional Nevus Advanced MM: vertical growth into dermis Dysplastic compound nevus Early MM: radial growth in epidermis, superficial dermis
  20. 20. Malignant melanoma Dysplastic melanocytes involve epidermis and invade the dermis
  21. 21. Malignant melanoma, radial & vertical growth phases Vertical downward growth into derm Radial growth Radial: proliferation of atypical melanocytes laterally within epidermis; Vertical: growth of melanocytes downward, invading into dermis
  22. 22. Superficial spreading Cell spread along Dermoepidermal jn
  23. 23.  Desmoplatic variety  Atypical melanocyte in desmoplastic stroma
  24. 24.  Staining with S-100 in desmoplastic melanoma
  25. 25. Nests of small blue cells, with minimal cytoplasm Electron Microscopy: membrane-bound dense core neurosecretory granules (blue arrows) and stacks of perinuclear cytokeratin filaments (black arrows)
  26. 26. Kaposi sarcoma  Numerous atypical, irregular angulated vascular channels  Promontory sign- irregular vascular channels that partially surround preexisting blood vessels.  Plasma cells in surrounding Stroma - classic finding
  27. 27.  Staining for HHV-8 in KS  IHC for HHV-8- been shown 99% sensitive 100% specific
  28. 28. Densely cellular spindle cells in radially arranged fascicles, invading into subcutis and muscle fibers. Main portion shows a storiform arrangement with extension into the subcutaneous fat, with fat entrapment creating a honeycomb pattern