Malignant Melanoma Bone Metastasis With Unknown Primary Site: A Case Report and Literature Review

Cases of malignant melanoma first identified in bone are relatively uncommon. Approximately 4.3% of the patients will have metastasis, among which 23% will have metastasis to the bone.

This article presents a case involving malignant melanoma with a metastatic lesion located at the distal femur, which was the initial symptom observed. The patient was a 21-year-old male who was admitted to the hospital due to intermittent pain in his lower left thigh. Imaging studies indicated bone destruction in the distal left femur, and pathological and immunohistochemical confirmed metastatic malignant melanoma. The patient underwent "resection of the tumor segment from the left distal femur followed by artificial knee arthroplasty," after which he received chemotherapy according to established protocols for advanced malignant melanoma. Currently, the patient's condition is stable, and no recurrence or metastasis has been observed upon re-examination.

This article details the diagnosis, treatment, and prognosis of a patient with malignant melanoma bone metastasis originating from an unknown primary lesion. Additionally, it reviews and analyzes relevant literature concerning malignant melanoma bone metastasis, emphasizing that clinicians should provide timely local and systemic interventions for patients presenting with malignant melanoma bone metastasis, even when the primary lesion remains unidentified.

For patients with malignant melanoma bone metastasis with unknown primary site, after a clear pathological diagnosis, surgical intervention and postoperative systemic treatment should be carried out in a timely manner to improve the overall survival rate of the patients.