Abstract
BACKGROUND: Giant malignant melanoma is an exceedingly rare and aggressive form of skin cancer. Although capable of growing beyond 10 cm in diameter, it often follows an indolent course while having an increased metastatic potential. This dual nature poses unique diagnostic and therapeutic challenges. Cases of giant malignant melanoma are rarely reported, particularly on the upper limb, making such occurrences notable for their atypical presentation and clinical significance. CASE PRESENTATION: We present a 47-year-old Brazilian woman who presented with symptomatic anemia and a 10 × 12 cm bleeding, fungating mass on her right arm. Histopathological evaluation and imaging confirmed the diagnosis of nodular malignant melanoma without evidence of metastasis. She underwent surgical excision of the mass without postoperative complications. The patient was subsequently discharged with a follow-up plan involving oncology for ongoing management and surveillance. CONCLUSION: This case represents the 20th report of giant malignant melanoma in the literature, and the fourth case specifically involving the arm, underscoring its rarity. It highlights the importance of heightened clinical suspicion and timely intervention in patients presenting with atypical, enlarging skin lesions. Furthermore, it emphasizes the critical role of a multidisciplinary approach in achieving optimal outcomes for such complex cases.