Atypical Melanoma of the Lateral Fifth Metatarsal Shaft: A Rare Presentation With Minimal Mitotic Activity

Melanoma of the foot is an uncommon malignancy that often presents with atypical clinical features, contributing to delayed diagnosis and poorer outcomes. We report a rare case of an 88-year-old female with a minimally mitotic, amelanotic melanoma arising from the lateral fifth metatarsal shaft, initially concealed beneath a callus. The lesion was painless in its early stages and not clinically apparent, resulting in a diagnostic delay of more than three years. Magnetic resonance imaging (MRI) ultimately revealed a pedunculated soft-tissue mass suspicious for malignancy. Given the presence of significant peripheral arterial disease, revascularization was performed prior to definitive surgical management. The patient subsequently underwent complete surgical excision of the lesion. Histopathological analysis confirmed melanoma classified as Not Otherwise Specified (NOS), a category used when tumors do not fit established histopathologic subtypes. This case highlights the diagnostic challenges associated with amelanotic and atypically located melanomas of the foot and underscores the importance of careful evaluation of persistent or unusual foot lesions. It emphasizes the need for heightened clinical suspicion in elderly and diabetic populations to facilitate earlier diagnosis and improved outcomes.