Germline mutations predisposing to melanoma

Nearly 15% of melanomas occur in patients with a family history and a subset of these patients have a germline mutation in a melanoma predisposing gene. CDKN2A mutations are responsible for the majority of hereditary melanoma, but many other susceptibility genes have been discovered in recent years, including CDK4, TERT, ACD, TERF2IP, POT1, MITF, MC1R, and BAP1. Additionally, melanoma risk is increased in mixed cancer syndromes caused by mutations in PTEN, BRCA2, BRCA1, RB1, and TP53. While early onset, multiple tumors, and family cancer history remain the most valuable clinical clues for hereditary melanoma, characteristic epithelioid cytology of melanocytic tumors may suggest an underlying BAP1 mutation. Herein, we review the clinical and histopathologic characteristics of melanocytic tumors associated with these germline mutations and discuss the role of genetic counseling.     

Chemotherapy reaction induced by ixabepilone,a microtubule stabilizing agent,mimicking extramammary Paget's disease in a patient with breast carcinoma

The histopathologic characteristics of reactions caused by the many novel anticancer agents are under‐recognized. We report a case of a 67‐year‐old female with locally advanced metastatic breast cancer, who initially presented with an extensive reticulated erythematous patch on the trunk caused by intravascular metastases confirmed by a skin biopsy. Owing to disease progression, she was started on ixabepilone, a mitotic inhibitor. While receiving ixabepilone, another skin biopsy was obtained and initially interpreted as extramammary Paget's disease. However, the biopsy showed metaphase arrest of numerous keratinocytes in the basilar and suprabasilar epidermis. Atypical epithelial cells were only present in the intravascular spaces similar to the initial biopsy. Given the temporal association between the initiation of ixabepilone therapy and the epidermal mitotic arrest, a diagnosis of chemotherapy reaction to ixabepilone was rendered. Ixabepilone is an analog of epothilone, a microtubule stabilizer causing mitotic arrest of the cell cycle approved for the treatment of metastatic and locally advanced treatment‐resistant breast cancer. The demonstration of epidermal mitotic arrest caused by ixabepilone is without precedent. The case emphasizes the importance of considering a chemotherapy reaction in the histologic differential diagnosis of epidermal mitotic arrest in a cancer patient receiving chemotherapy.