Malignant melanoma is a prevalent and aggressive skin neoplasm arising from melanocytes, known for its varied clinical manifestations. One particularly challenging aspect of metastatic melanoma is its potential to present atypically before the identification of the primary lesion. We report a rare case involving a 67-year-old male who developed a painless, enlarging mass in the right axilla over a period of four weeks. Ultrasound and magnetic resonance imaging (MRI) scans revealed a well-defined solitary lesion in the right axilla with cystic characteristics and a distinct fluid–fluid level. An ultrasound-guided biopsy of the lesion confirmed the diagnosis of metastatic melanoma.
While hemorrhagic metastases are a recognized complication of malignant melanoma, particularly affecting the brain and lungs, the presentation of soft tissue metastases exhibiting fluid–fluid levels is less commonly documented in the literature. This case underscores the importance of considering melanoma metastasis in the differential diagnosis when encountering such lesions. The imaging characteristics can often resemble those of a hemorrhagic soft tissue sarcoma, necessitating histopathological confirmation through ultrasound-guided biopsy, as management strategies for these conditions differ significantly. This case emphasizes the need for heightened awareness among clinicians regarding the atypical presentations of metastatic melanoma and the critical role of imaging and biopsy in ensuring accurate diagnosis and effective treatment.
