Practice question answers, skin tumors 1

Practice question answers, skin tumors 1

© Jun Wang, MD, PhD

1. C. Epidermal proliferation with pseudohorn cysts is most consistent with seborrheic keratosis. Actinic keratosis has dysplasia limited to basal layer, usually not epidermal proliferation or pseudohorn cysts. Merkel cell carcinoma has intradermal sheets of poorly differentiated cells with scant cytoplasm and express neuroendocrine markers such as CD56, synaptophysin and chromogranin. Squamous cell carcinoma has irregular nests or cords of atypical squamous cells with intercellular bridges and/or keratin pearl formation. Verruca vulgaris is caused by human papillomavirus and usually has koilocytes.

2. B. The skin lesion has epidermal proliferation with pseudohorn cysts, most consistent with seborrheic keratosis. Sudden increased number of seborrheic keratosis is suggestive of Leser-Trelat syndrome, associated with internal organ malignancies, especially GI tract. This patient has clinical presentations of dysphagia and weight loss, with a history of Barrett’s esophagus, highly suspicious for esophageal adenocarcinoma. Guttate psoriasis is scaly dermatosis with psoriasiform epidermal hyperplasia. Neurofibromatosis 1 has multiple neurofibromas, characterized by proliferation of spindle cell with slender nuclei, and positive reactivity to S100. Nevoid basal cell carcinoma syndrome has basal cell carcinoma. Sezary syndrome has diffuse erythroderma, lymphadenopathy and CD4 positive malignant Sezary cells in peripheral blood.

3. C. See discussion of question 2. Abnormal keratinocyte turnover is seen in psoriasis. Human papillomavirus may cause wart, and a small portion of squamous cell carcinoma of skin. NF 1 mutation is seen in neurofibromatosis 1. UV light is the most important cause of skin cancers, including squamous cell carcinoma, basal cell carcinoma and melanoma.

4. C. Skin hyperpigmentation at folds with mildly thickened skin is likely acanthosis nigricans, a condition possibly associated with internal malignancies, or insulin resistance. Acute bacterial infection or fungal infection usually has erythematous changes, edema, and scaly surface. Melanocytic proliferation usually has well demarcated borders. Metastatic cancer has mass formation.

5. A. Polypoid skin growth of with a fibrovascular core covered by benign epidermis and lack adnexa is acrochordon. Dermatofibroma is a well defined intradermal spindle cell proliferation that is positive for factor XIIIa and negative for CD34. Dermatofibrosarcoma protuberans is an invasive hypercellular dermal spindle cell proliferation with cytological atypia, and is positive for CD34 and negative for factor XIIIa. Neurofibroma has spindle cell with slender nuclei, and positive reactivity to S100. Schwannoma has cellular component(Antoni A) that palisades (Verocay bodies), and myxoid component (Antoni B).

6. B. Skin cyst with greasy contents and lined by epidermis with granular layer is epidermal cyst. Dermatophytosis is fungal infection but not cyst formation. Pilar cyst is lined by epidermal without granular layer and has packed solid contents. Pilomatrixoma is characterized by sheets of basaloid cells and ghost cells. Teratoma is germ cell tumor with mature skin differentiation in other structures, such as ovary.

7. B. See discussion of question 6. Squamous cell carcinoma has irregular nests or cords of atypical squamous cells with intercellular bridges and/or keratin pearl formation.

8. D. Well demarcated skin growth of small keratinocytes connecting to epidermis is most consistent with eccrine poroma. Actinic keratosis has dysplasia limited to basal layer. Basal cell carcinoma has irregular budding, nest, cords of basaloid cells with scant cytoplasm with peripheral palisading. Cylindroma has compact nests of basaloid cell forming a jigsaw puzzle pattern separated by thick basement membrane. Squamous cell carcinoma has irregular nests or cords of atypical squamous cells with intercellular bridges and/or keratin pearl formation.

9. B. See discussion of question 8. Syringoma has benign small tadpole shaped glandular proliferation in a fibrotic background.

10. C. Multiple cylindromas with a positive family history are consistent with the familial form (turban tumor syndrome, Brooke-Spiegler syndrome) that is associated with CYLD mutation. Beta-catenin mutation can be seen in ovarian endometrioid adenocarcinoma, stomach cancer, colon adenoma, solid-pseudopapillary neoplasm and pilomatricoma. BRAF mutation can be seen in various disorders, including melanocytic nevus and melanoma. MSH2 is a DNA mismatch repair gene and its mutation is seen in colon cancer, Lynch syndrome and its variant Muir-Torre syndrome, etc. PTCH mutation is seen basal cell carcinoma.

11. E. Syringoma has benign small tadpole shaped glandular proliferation in a fibrotic background. Cylindroma has compact nests of basaloid cell forming a jigsaw puzzle pattern separated by thick basement membrane. Eccrine poroma has well demarcated skin growth of small keratinocytes connecting to epidermis. Invasive ductal carcinoma has irregular ducts lined by atypical cells. Sebaceous adenoma has lobulated growth of generative cells (dark) and sebaceous cells (light).

12. C. Sebaceous adenoma has lobulated growth of generative cells (dark) and sebaceous cells (light). When associated with presentation of Lynch syndrome, as seen in this case as early onset of colon cancer, and family history of associated malignancies, it is likely Muir-Torre syndrome. Brooke-Spiegler syndrome is familial form of cylindromas. Cowden syndrome has multiple tricholemmoma, hamartomas and associated malignancies. Neurofibromatosis 2 has schwannoma, meningiomas, café au lait, etc. Nevoid basal cell carcinoma syndrome has basal cell carcinoma.

13. D. See discussion of question 10.

14. C. Pilomatrixoma is characterized by sheets of basaloid cells and ghost cells. Cylindroma has compact nests of basaloid cell forming a jigsaw puzzle pattern separated by thick basement membrane. Pilar cyst is lined by epidermal without granular layer and has packed solid contents. Sebaceous adenoma has lobulated growth of generative cells (dark) and sebaceous cells (light). Syringoma has benign small tadpole shaped glandular proliferation in a fibrotic background.

15. E. Benign basaloid and squamous proliferation with primitive hair follicle is consistent with trichoepithelioma. Basal cell carcinoma has irregular budding, nest, cords of basaloid cells with scant cytoplasm with peripheral palisading. Cylindroma has compact nests of basaloid cell forming a jigsaw puzzle pattern separated by thick basement membrane. Epidermal cyst has greasy contents and lined by epidermis with granular layer. Pilomatrixoma is characterized by sheets of basaloid cells and ghost cells.

16. E. Lobular or plate-like growth of pale pink, glassy cells with palisading at periphery is compatible with tricholemmoma. Basal cell carcinoma has irregular budding, nest, cords of basaloid cells with scant cytoplasm with peripheral palisading. Cylindroma has compact nests of basaloid cell forming a jigsaw puzzle pattern separated by thick basement membrane. Trichoepithelioma has benign basaloid and squamous proliferation with primitive hair follicle formation. Eccrine poroma has well demarcated skin growth of small keratinocytes connecting to epidermis.

17. A. Well defined dermal spindle cell proliferation with immunohistrochemistry profiles of positive factor XIIIa and negative CD34 expression is consistent with dermatofibroma. Dermatofibrosarcoma protuberans has invasion, and is positive for CD34 and negative for factor XIIIa. Leiomyoma is positive for desmin. Melanoma and neurofibroma are positive for S100.

18. B. See discussion of question 17.

19. D. Dermatofibrosarcoma protuberans is associated with fusion of COL1A1 and PDGFB. Also see discussion of question 10.

20. D. Spindle cell proliferation with slender nuclei and positive reactivity to S100 is consistent with neurofibroma. Dermatofibroma is positive for factor XIIIa. Dermatofibrosarcoma protuberans is positive for CD34. Leiomyoma is positive for desmin. Skin tag is polypoid skin growth of with a nonneoplastic fibrovascular core covered by benign epidermis and lack adnexa. It is negative for S100.

21. C. Multiple neurofibromas with the presence of café au lait and Lisch nodules are consistent with neurofibromatosis 1, associated with mutation of NF1 (neurofibromin). BRAF mutation can be seen in various disorders, including melanocytic nevus and melanoma. Neurofibromatosis 2 has schwannoma, meningiomas, café au lait, etc, but not Lisch nodules, and is associated with merlin (NF2) mutation. PDGFB abnormality is associated with dermatofibrosarcoma protuberans. PTCH mutation is seen basal cell carcinoma.

22. E. Schwannoma has cellular component (Antoni A) that palisades (Verocay bodies), and myxoid component (Antoni B). Fibrosarcoma is hypercellular spindle cell neoplasm with a herringbone pattern. Leiomyoma has cigar shaped nuclei. Meningioma has meningothelial whorls. Neurofibroma has slender nuclei. None of these has Antoni A and Antoni B components.

23. B. Presence of schwannoma and café au lait is consistent with neurofibromatosis 2, associated with merlin mutation. Also see discussion of question 22.

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