This article discusses a case of melanoma in a congenital melanocytic nevus, a rare occurrence that can lead to serious health risks if not diagnosed and treated promptly. The patient, a 69-year-old woman, presented with new-onset pruritus and hyperpigmentation in a nevus on her lower back. Dermoscopy revealed findings concerning for malignancy, and a biopsy confirmed superficial spreading melanoma. The patient underwent surgical excision and lymph node biopsy, and no metastasis was found. The article emphasizes the importance of early identification and treatment of melanoma in congenital melanocytic nevi, particularly in cases involving larger nevi or patients under the age of 5. Regular skin assessments and monitoring are recommended for individuals at higher risk. [Extracted from the article]