Practice question answers, skin tumors 2

Practice question answers, skin tumors 2
© Jun Wang, MD, PhD

1. A. Dysplasia limited to basal layer is most consistent with actinic keratosis. Basal cell carcinoma has irregular budding, nest, cords of basaloid cells with scant cytoplasm with peripheral palisading. Bowen disease has full thickness dysplasia. Dermatophytosis is fungal infection and has intraepidermal neutrophilic infiltration but not keratinocytic atypia. Melanoma in situ has Pagetoid spread of atypical melanocytes.

2. E. Actinic keratosis is a squamous precancerous lesion and may develop into squamous cell carcinoma or basal cell carcinoma.

3. E. This lesion has irregular nest, cords of basaloid cells with scant cytoplasm with peripheral palisading, characteristic for basal cell carcinoma. The most important carcinogenic factor for melanoma, squamous cell carcinoma or basal cell carcinoma is UV light from sun exposure. Abnormal keratinocytic turnover is seen various lesions, including psoriasis. Chronic irritation, HPV may be associated with a small portion of these tumors. Insulin resistance is associated with dermatophytosis, acanthosis nigricans, but not keratinocytic neoplasm.

4. B. This lesion has irregular nest, cords of basaloid cells with scant cytoplasm with peripheral palisading, characteristic for basal cell carcinoma. Actinic keratosis has dysplasia limited to basal layer. Cylindroma has compact nests of basaloid cell forming a jigsaw puzzle pattern separated by thick basement membrane. Psoriasis has elongated rete ridges without dysplasia or invasion. Tricholemmoma has lobular or plate-like growth of pale pink, glassy cells with palisading at periphery.

5. C. This lesion has irregular cords of basaloid cells in a fibrotic background, characteristic for morphea form basal cell carcinoma, and likely to have perineural invasion. Basal cell carcinoma rarely metastasize. Multifocality is seen in superficial type basal cell carcinoma. Primitive hair follicles are seen in trichoepithelioma. Squamous pearls are commonly seen in well differentiated squamous cell carcinoma.

6. C. Any invasive carcinoma at sensitive locations such as face need Mohs surgery, especially morphea form basal cell carcinoma.

7. B. This lesion has irregular cords of basaloid cells in a fibrotic background, characteristic for morpheaform basal cell carcinoma. Actinic keratosis has dysplasia limited to basal layer. Cylindroma has compact nests of basaloid cell forming a jigsaw puzzle pattern separated by thick basement membrane. Syringoma has benign small tadpole shaped glandular proliferation in a fibrotic background. Tricholemmoma has lobular or plate-like growth of pale pink, glassy cells with palisading at periphery.

8. B. This lesion has irregular budding of basaloid cells from basal layer, characteristic for superficial type basal cell carcinoma, and likely to be multifocal. Also see discussion of question 5.

9. B. See discussion of questions 7 and 8.

10. This lesion has irregular nests of basaloid cells in dermis, characteristic for basal cell carcinoma, commonly associated with PTCH 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. CYLD mutation is seen familial form cylindromas (turban tumor syndrome, Brooke-Spiegler syndrome). MSH2 is a DNA mismatch repair gene and its mutation is seen in colon cancer, Lynch syndrome and its variant Muir-Torre syndrome, etc.

11. D. This lesion has poorly differentiated small cells that are positive for cytokeratin and neuroendocrine marker CD56. Without molding and crush nuclear features, this is more likely to be Merkel cell carcinoma, that is commonly positive for CK20, but negative for CK7. CD3 is a T cell marker and CD20 is a B cell marker. Desmin is muscular marker. None of these three is positive for Merkel cell carcinoma, and usually muscular and lymphoid tumors are negative for cytokeratin.

12. D. Skin tumor with poorly differentiated small cells that are positive for cytokeratin and neuroendocrine marker CD56, without molding and crush nuclear features, is more likely to be Merkel cell carcinoma. Basal cell carcinoma has irregular budding, nest, cords of basaloid cells with scant cytoplasm with peripheral palisading, but not sheets of poorly differentiated cells. Cylindroma has compact nests of basaloid cell forming a jigsaw puzzle pattern separated by thick basement membrane. Diffuse large B cell lymphoma has large atypical cells that are positive for CD45 but negative for cytokeratin. Eccrine poroma has well demarcated skin growth of small keratinocytes connecting to epidermis.

13. C. Full thickness epidermal dysplasia without dermal invasion is consistent with Bowen disease. 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. Squamous cell carcinoma has intradermal irregular nests or cords of atypical squamous cells with intercellular bridges and/or keratin pearl formation. Melanoma in situ has Pagetoid spread of atypical melanocytes.

14. E. Intradermal irregular nests or cords of atypical squamous cells with intercellular bridges and/or keratin pearl formation is consistent with squamous cell carcinoma. The most important carcinogenic factor for melanoma, squamous cell carcinoma or basal cell carcinoma is UV light from sun exposure. Cigarette smoking and HPV may be associated with a small portion of these tumors. Molluscum contagiosum virus is associated with molluscum contagiosum. Polyvinyl chloride is associated with angiosarcoma of liver.

15. D. Intradermal irregular nests or cords of atypical squamous cells with intercellular bridges and/or keratin pearl formation is consistent with squamous cell carcinoma. Actinic keratosis has dysplasia limited to basal layer. Bowen disease has full thickness epidermal dysplasia. Epidermal cyst has greasy contents and lined by epidermis with granular layer. Tricholemmoma has lobular or plate-like growth of pale pink, glassy cells with palisading at periphery.

16. A. This lesion is characterized by large CD3 positive T cells in epidermis, a features highly suggestive of mycosis fungoides, usually with marked elevated CD4/CD8 ratio. Pair of CD5 and CD23 are used to differentiate mantle cell lymphoma from small lymphocytic lymphoma, both are CD20 positive B cell lymphoma. CD15 and CD30 are usually positive in Hodgkin lymphoma, characterized by Reed-Sternberg cells. CK7 and CAM5.2 may be positive for Paget disease of breast, genital area, or other locations. HMB45 and S100 are positive for melanoma.

17. C. Atypical CD4 positive T cell infiltration in epidermis is most consistent with mycosis fungoides. Dermatophytosis is fungal infection and has intraepidermal neutrophilic infiltration and mixed lymphocytic infiltrate. Lichen planus has band like dense mixed normal appearing lymphocytic infiltrate at dermal epidermal junction. Psoriasis has elongated rete ridges without dysplasia or invasion. Sezary syndrome has erythroderma, lymphadenopathy and Sezary cells in peripheral blood and lymph nodes.

18. D. See discussion of question 17. Mycosis fungoides has four different stages. This is likely tumoral stage due to tumor formation. Bowen disease has full thickness epidermal dysplasia.

19. A. Erythroderma, lymphadenopathy and Sezary cells in peripheral blood and lymph nodes are consistent with Sezary syndrome, and the tumor cells are CD4 positive T cells that also express T cell marker CD3. CD11c is positive for hairy cell leukemia. CD20 is a pan B cell marker. CD30 is positive for Hodgkin lymphoma and anaplastic large cell lymphoma, Reed-Sternberg cells are seen in former and markedly atypical lymphocytes are seen in the later. CD138 is a plasma cell marker that is positive in multiple myeloma, plasmacytoma, lymphoplasmacytic lymphoma, etc.

20. E. Erythroderma, lymphadenopathy and Sezary cells in peripheral blood and lymph nodes are consistent with Sezary syndrome. Chronic lymphocytic leukemia and chronic myeloid leukemia usually have markedly elevated white cell count with circulating small lymphocytes with soccer ball appearance or less mature myeloid cells. Hairy cell leukemia usually has pancytopenia and circulating B lymphocytes with round nuclei and fine hairy projections.


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