Supplementary Material for: Metastatic Subungual Melanoma of the Hallux

Background: Subungual melanoma is a rare and aggressive variant of acral lentiginous melanoma, often misdiagnosed in its early stages. It typically affects older individuals and has a poor prognosis due to delayed recognition. Management is further complicated in low-resource or conflict-affected settings. Case Presentation: We report the case of a 52-year-old Syrian male with no significant past medical history who presented with an ulcerative lesion on his left hallux. Histopathological evaluation following excisional biopsy and hallux amputation revealed ulcerated malignant melanoma, Clark level V, with subcutaneous invasion but no bone involvement. Regional lymph node dissection identified one metastatic inguinal node (pN1). Despite initial surgical management, the disease progressed within four months, with PET-CT revealing hepatic and pulmonary metastases (Stage IV). The patient tested negative for BRAF mutations, and due to unavailability of immunotherapy, was treated with systemic chemotherapy (carboplatin and paclitaxel). Case Discussion: This case highlights the diagnostic and therapeutic challenges in managing advanced subungual melanoma, particularly in settings with limited access to molecular testing and modern therapies. The lesion’s aggressive course and rapid progression despite surgery reflect the poor prognosis associated with late-stage ALM and the necessity of early recognition. Comparisons with similar cases from the literature reveal both unique and shared features in tumor behavior, diagnosis, and treatment strategy. Conclusion: Subungual melanoma can progress rapidly and metastasize even after seemingly adequate local treatment. Early detection, prompt excision, and access to targeted and immune-based therapies are crucial to improving outcomes. In resource-limited environments, comprehensive care is further hindered, underscoring the importance of global efforts to improve cancer care equity.