Practice question answers, skin tumors 3

Practice question answers, skin tumors 3

© Jun Wang, MD, PhD

1. E. The lesion is characterized by partial or complete loss of melanin pigmentation without other abnormalities, most consistent with vitiligo. Actinic keratosis is a squamous precancerous lesion with rough surface or cutaneous horn. Dermatophytosis is fungal infection and is usually an erythematous, centrifugally growing annular lesion with a peripheral scale. Scar may have hypopigmentation but usually has a bulging appearance due to regenerative changes.

2. C. Vitiligo is associated with autoimmune destruction of melanocytes. Allergic reaction is associated with various dermatitis, including allergic contact dermatitis, urticaria, and erythema multiforme, etc. Excess estrogen associated hyperpigmentation is seen in melasma. Sun exposure is associated with hyperpigmentation, such as melasma, and proliferative disorders lentigo, melanoma, squamous cell carcinoma and  basal cell carcinoma. Tyrosinase mutation is more commonly seen in albinism.

3. C. Sudden onset of hyperpigmentation in a young, otherwise healthy pregnant woman is most likely melasma, an estrogen associated harmless condition. BRAF mutation can be seen in various disorders, including melanocytic nevus and melanoma. Cigarette smoking is a risk factor for many conditions, including lung, larynx and oral cavity cancer, but not melasma. Melanocytic proliferation is seen in lentigo, melanocytic nevus and melanoma.

4. E. Sudden onset of hyperpigmentation in a young, otherwise healthy pregnant woman is most likely melasma, an estrogen associated harmless condition. Actinic keratosis is a squamous precancerous lesion with rough surface or cutaneous horn. Bowen disease has full thickness epidermal dysplasia and clinical it has rough, irregular, scaly patches. Melanocytic nevus and melanoma usually have more well demarcated darker appearance.

5. D. Linear small melanocytic proliferation with slightly elongated rete ridges is most likely lentigo. Actinic keratosis has dysplasia limited to basal layer. All melanocytic nevi have nested melanocytic proliferation. Lentigo maligna is a type of melanoma in situ, characterized by nests of atypical melanocytes at and beyond basal layer without dermal involvement.

6. E. Nests of atypical melanocytes at and beyond basal layer but not in dermis is lentigo maligna. Actinic keratosis has keratinocytic dysplasia limited to basal layer. Dysplastic nevus has bridges of melanocytes beyond at least three rete ridges. Junctional nevus has nests of benign melanocytes at basal layer without bridges. Lentigo has linear small melanocytic proliferation only in basal layer. Lentigo maligna melanoma is invasive melanoma with atypical melanocytes in dermis.

7. D. See discussion of question 6. Paget diseases of breast, genital area, or other locations are adenocarcinoma spread in epidermis and are positive for CK7 and CAM5.2 but negative for S100 and HMB45.

8. E. Sun exposure is the most important risk factor for lentigo, melanoma, squamous cell carcinoma and  basal cell carcinoma. Adenocarcioma nearby is associated with Paget diseases of breast. Alcohol, cigarette and HPV are less likely associated with melanoma.

9. C. Nests of benign matured melanocytes (small nuclei) at basal layer only is most consistent with junctional nevus. Dysplastic nevus has bridges of melanocytes beyond at least three rete ridges. Intradermal nevus has nests of benign matured melanocytes (small nuclei) only in dermis. Lentigo has linear small melanocytic proliferation only in basal layer. Lentigo maligna is a type of melanoma in situ, characterized by nests of atypical melanocytes at and beyond basal layer without dermal involvement.

10. B. See discussion of question 9. Melanoma has atypical immature melanocytes (large atypical nuclei) in dermis. Neurofibroma is a spindle cell tumor with slender nuclei.

11. A. Nests of benign matured melanocytes (small nuclei) at basal layer and in dermis are features of compound nevus. Dysplastic nevus has bridges of melanocytes beyond at least three rete ridges. Intradermal nevus has nests of benign matured melanocytes (small nuclei) only in dermis. Junctional nevus has nests of benign melanocytes only at basal layer without bridges. Melanoma has atypical immature melanocytes (large atypical nuclei) in dermis.

12. A. 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. PDGFB abnormality is associated with dermatofibrosarcoma protuberans. PTCH mutation is seen basal cell carcinoma.

13. A. See discussion of question 11. Melanoma in situ is characterized by nests of atypical melanocytes at and beyond basal layer (Pagetoid spread) without dermal involvement.

14. C. Dysplastic nevus is a melanocytic neoplasm with significant risk factor for melanoma, but not for keratinocytic tumors such as squamous cell carcinoma and  basal cell carcinoma, or lymphomas such as adult T cell lymphoma or mycosis fungoides.

15. C. Atypical cells spread in epidermis (Pagetoid spread) seen in a patient with previous breast cancer raise the concern for either Paget disease or melanoma in situ, former positive for CK7 and negative for HMB45, and the later negative for CK7 but positive for HMB45. CD3 and CD20 are used to differentiate T and B lymphocyte population. CD4 and CD8 are used to exam T lymphocytes population. Cytokeratin and CD45 are used to differentiated epithelial cells from leukocytes. Sliver stain for fungus is used to detect fungal hyphae in dermatophytosis that usually has intraepidermal neutrophilic infiltration and mixed lymphocytic infiltrate.

16. D. Melanoma in situ is characterized by nests of atypical melanocytes at and beyond basal layer (Pagetoid spread) without dermal involvement. Invasive melanoma with atypical melanocytes in dermis. Junctional nevus has nests of benign melanocytes only at basal layer without bridges. Lentigo has linear small melanocytic proliferation only in basal layer. Paget disease is usually positive for CK7 and negative for HMB45.

17. B. Atypical melanocytes in dermis, as shown by positive HMB45 reactivity, is consistent with invasive melanoma. Compound nevus has nests of benign matured melanocytes (small nuclei) at basal layer epidermis and in dermis. Melanoma in situ is characterized by nests of atypical melanocytes at and beyond basal layer (Pagetoid spread) without dermal involvement. Hodgkin lymphoma has CD15 and CD30 positive Reed-Sternberg cells, but does not express HMB45. Squamous cell carcinoma has intradermal irregular nests or cords of atypical squamous cells with intercellular bridges and/or keratin pearl formation, but does not express HMB45.

18. E. Sun exposure is the most important risk factor for lentigo, melanoma, squamous cell carcinoma and  basal cell carcinoma. Alcohol, cigarette and HPV are less likely associated with melanoma. EB virus is associated with Hodgkin lymphoma.

19. C. The most important prognostic factor for invasive melanoma is the depth of invasion, as defined by the distance between granular layer to the deepest tumor cells.

20. B. This is an intradermal nodular growth of tumor cells with moderate to abundant pale cytoplasm, most consistent with nodular type invasive melanoma. Tumor cells of basal cell carcinoma and Merkel cell carcinoma have scant cytoplasm. Melanoma in situ is characterized by nests of atypical melanocytes at and beyond basal layer (Pagetoid spread) without dermal involvement. Squamous cell carcinoma has intradermal irregular nests or cords of atypical squamous cells with intercellular bridges and/or keratin pearl formation.

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