Subungual Melanoma In Situ in a Hispanic Girl Treated With Functional Resection and Reconstruction With Onychocutaneous Toe Free Flap
Archives of dermatology (Impact Factor: 4.79). 01/2008; 143(12):1600-2. DOI: 10.1001/archderm.143.12.1600
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ABSTRACT: The etiology of longitudinal melanonychia (LM) is difficult to establish by clinical and dermoscopic examinations alone. Microscopic examination of the nail matrix remains crucial. Two groups of LM may be identified: melanocytic activation (melanic pigmentation of the matrix epithelium without any increase in the density of melanocytes) and melanocytic proliferation (lentigo, nevus, or melanoma). The histological examination is challenging, and immunohistochemical investigations can be helpful. The objective of this study was to analyze the immunohistochemical findings with routinely used markers in melanocytic tumors-S-100 protein, HMB-45, and Melan-A-in LM. A series of 40 cases were analyzed: 10 activations, 4 lentigines, 7 nevi, 12 in situ melanomas, and 7 invasive melanomas. The sensitivity of S-100 protein is weak in benign and malignant intraepithelial melanocytes of the nail matrix, and if this marker is performed alone, it may be wrongly reassuring. However, the use of S-100 protein is essential to differentiate invasive melanoma, lacking an intraepithelial component, and particularly desmoplastic melanoma, from epithelial and mesenchymal tumors. HMB-45 and Melan-A are more sensitive than S-100 protein for the evaluation of intraepithelial melanocytic proliferation of the nail apparatus, with HMB-45 being the most intense marker. In the dermal component, HMB-45 and Melan-A were less sensitive than S-100 protein. In conclusion, we recommend that the panel of antibodies used for histological evaluation of LM should include HMB-45 and/or Melan-A and S-100 protein only if an invasive melanoma is suspected.
Article: Subungual Malignant Melanoma
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ABSTRACT: Subungual melanoma (SUM) is infrequent in the general population, accounting for 0.7-3.5% of all cutaneous melanomas. SUM absolute incidence is similar among different racial groups; however, the relative proportion among overall cutaneous melanoma cases within each population varies in relation to the frequency of sun-induced melanoma. Subungual melanoma most commonly presents as a discoloration of the nail, followed by a recalcitrant wound, a tumor, nail splitting and nail bed bleeding. In most cases, the clinical presentation will already exhibit features typical of late-stage lesions because many patients wait for several months or even years before consulting a physician for evaluation of nail changes. Misdiagnosis of SUM as subungual hematoma, chronic trauma or onychomycosis is still a frequent occurrence, significantly reducing the chances for early treatment. An appropriate diagnostic approach is crucial to allow early-stage diagnosis. The correct management of SUM hinges on early diagnosis and selection of the most appropriate surgical technique. Curative treatment of SUM currently entails surgical excision when the extent of invasion is limited.
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