RESUMO
Introduction and importance: Melanoma represents only 1% of all skin cancers. Acral lentigious melanoma (ALM) which usually arises from feet, is the rarest main subtype of melanoma. Subungual melanoma (SUM) is a rare variant of ALM. Amelanotic melanoma (AM) is found only in 4-27.5% of melanomas, and the mean age for patients affected by AM exceeds 50 years. Late diagnosing leads to unfavourable prognosis. Case presentation: The authors present a case of subungual amelanotic melanoma that affected the nail unit of the right thumb which is a rare case, especially when the patient is only 39 years old. The lesion enlarged over a year and was misdiagnosed many times and treated with no response. Sentinel node biopsy was positive and the patient was moved to a specialized hospital for treatment. Clinical discussion: Diagnosing subungual amelanotic melanoma is challenging, not only because it is the rarest, but also it mimics many benign and malignant neoplasms due to the lack of pigmentation, in addition to the absence of clinical diagnostic features. AM exhibits a high growth rate helping in limiting the window for early detection. Conclusions: Lately diagnosed subungual amelanotic melanoma usually associates with an increased risk of metastases, So it should be considered as a cause of any non-healing lesion. Early diagnosing gives patients the best chance for survival.
