18303 Ataxia telangiectasia and melanoma: The role of dermatology in ataxia telangiectasia

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Conference Proceeding

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Publication Title

J Am Acad Dermatol


Presentation: A 28-year-old Caucasian woman with ataxia telangiectasia (AT), hypothyroidism, diabetes, uterine leiomyomas, liver adenoma, and hypogammaglobulinemia presented with a 6-month history of growth of melanocytic lesion which had previously been stable for the 4-5 years. Physical examination revealed a large, dark brown macule on the right lateral foot. Course and Therapy: Shave biopsy revealed a broad, uneven proliferation of atypical, pleomorphic melanocytes with prominent nucleoli with cleaved nuclei. Breslow thickness was 1.4 mm with positive margins, 1 mitosis/mm2, and no ulceration. Immunohistochemical staining revealed diffusely positive HMB45, MIB-1 present in >10% of dermal melanocytes in some foci, preservation of p16, no mutation in BRAFV600E nor loss of BAP1. Wide local excision of 2 cm margins revealed invasive melanoma with Breslow thickness of 0.81 mm and melanoma in situ. Sentinel lymph node biopsy revealed incidental nodal nevus. Discussion: Ataxia telangiectasia (AT) is an autosomal recessive mutation in the ATM gene on chromosome 11 characterized by early onset cerebellar ataxia, oculocutaneous telangiectasias, immunodeficiency, and progressive respiratory failure. Incidence of malignancy is 37-fold in AT compared with the general population, as the ATM mutation impedes the ability of the tumor suppressor protein p53 to halt the cell cycle for DNA repair causing cells to accumulate damaged DNA. Approximately 85% of malignancies are hematopoietic. The incidence of melanoma in AT has not yet been characterized; however, the incidence of melanoma, like other malignancies, is increased in AT relatives. In the general population, 5%-10% of melanomas have been associated with somatic ATM mutations.





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