A rare case of fully regressive melanoma in the absence of metastasis

Fully regressive melanoma is an exceedingly rare phenomenon characterized by the complete histopathologic disappearance of malignant melanocytes, replaced by fibrosis, melanophages, and lymphocytic infiltrates, without identifiable residual tumor cells. We report the case of a 71-year-old female who presented with a pigmented lesion of the right auricle, which was incidentally noted by her daughter. Clinical examination revealed a darkly pigmented, asymmetrical macule with retention of hair follicles, raising suspicion for a benign melanocytic nevus. Excisional biopsy revealed complete regression of a superficial spreading melanoma without measurable Breslow thickness or vertical growth phase. Immunohistochemical studies demonstrated positivity for melanocytic markers and a low proliferative index, while imaging with PET/computed tomography and MRI revealed no evidence of regional or distant metastasis. Given the absence of high-risk features, sentinel lymph node biopsy was not performed, and the patient underwent wide local excision with no residual malignancy identified. She remains disease-free under close clinical follow-up. This case highlights the diagnostic and management challenges associated with fully regressive melanoma and emphasizes the need for heightened clinical suspicion and individualized treatment strategies. Further research is required to better understand the prognostic significance and optimal follow-up protocols for this rare melanoma subtype.