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Case of sarcomatoid carcinoma occurring in a patient with Werner syndrome

thus, early diagnosis is extremely important. However, early diagnosis is difficult and challenging. We should discriminate subungual melanoma from benign lesions, such as subungual lentigo or nevus. Most subungual melanomas show longitudinal melanonychia. The nail streak due to melanin arises in the nail matrix so that the color intensity does not reflect the malignancy. Histological confirmation is recommended, however, it is also challenging. In early cases, mitosis is not observed or rare. Nuclear atypicality is from faint to severe. Atypical melanocytes sometimes have large atypical nuclei and long dendrites. Cell density is sparse in some cases. Atypical melanocytes are found in the basal and/or in the suprabasal layer; especially, suprabasal scattering is more specific (Fig. 1d). Importantly, atypical melanocytes are found in the nail matrix, less in the nail bed and more in the surrounding areas, such as in the nail folds or in the hyponychium (Fig. 1e), which phenomenon is not observed in the benign lesions. Total surgical resection may be acceptable for the precise diagnosis and for fear of the poor prognosis of melanoma.