Subungual melanoma: a case report of delayed diagnosis despite multiple biopsies

Rebeca Martins, Department of Dermatology, Division of Dermatology, Hospital Universitário Getúlio Vargas, Manaus, Brazil Daniela Vale-Dias, Department of Dermatology, Division of Dermatology, Hospital Universitário Getúlio Vargas, Manaus, Brazil Thalyssa Figueiredo-Magalhães, Department of Dermatology, Division of Dermatology, Hospital Universitário Getúlio Vargas, Manaus, Brazil Vanessa R. Ferreira, Department of Dermatology, Division of Dermatology, Hospital Universitário Getúlio Vargas, Manaus, Brazil Bruna R. Santana-Vollrath, Universidade do Estado do Amazonas, Manaus, Brazil Luciana Mendes-dos Santos, Department of Dermatology, Hospital Universitário Getúlio Vargas, Manaus, Brazil Aline Guimarães-Grana, Department of Dermatology, Hospital Universitário Getúlio Vargas, Manaus, Brazil

Subungual melanoma is a rare presentation of melanoma, accounting for approximately 3% of all cases of this neoplasm. In this case, the diagnosis was only confirmed after the third biopsy, highlighting the importance of suspecting malignancy based on clinical history and dermatological examination. This report describes the case of a 43-year-old female patient with longitudinal melanonychia on the first and third digits of the right hand. She had undergone two previous biopsies, both showing no evidence of malignancy on histopathological analysis. However, due to high clinical suspicion, a third biopsy was performed, confirming a diagnosis of subungual melanoma in situ. In most cases, the prognosis is poor, with frequent bone metastases. The rarity of this melanoma presentation, combined with the diagnostic challenges and the low survival rate, justifies the report of this case.

Keywords: Subungual melanoma. Longitudinal melanonychia. Delayed diagnosis. Nail biopsy.