Metastatic Malignant Melanoma - Erler Zimmer
Clinical History
A 65-year-old male presents with discomfort in his left groin, having a history of skin melanoma on his left foot treated with surgical resection and radiotherapy. On examination, he appears cachexic, with an enlarged, hardened liver and a discharging sinus in the left groin surrounded by black nodules. He is admitted to the hospital and unfortunately succumbs to hospital-acquired pneumonia.
Pathology
The specimen consists of the patient's proximal right femur, sawn longitudinally to display the cut surface. The medullary cavity harbors numerous tumor deposits ranging in color from pale brown to black. Larger deposits, measuring up to 3 cm in diameter, completely obliterate cancellous bone, appearing dark. Additionally, diffuse pale brown tumor infiltrates the marrow cavity elsewhere. Cortical bone remains spared, except at the shaft and neck junction, where medial cortical bone is discolored and thickened. These findings represent metastatic deposits from a melanoma originating in the skin.
Further Information
Melanoma, a malignant skin cancer associated with UV radiation exposure, sunlight, or tanning beds, is characterized by a high mortality rate among skin cancers, constituting approximately 5% of skin cancer diagnoses. Typically found in sun-exposed areas, melanomas present as pigmented lesions with irregular borders, variegated color, asymmetrical shapes, and evolving characteristics over time. Common mutations in melanoma include loss of the cell cycle control gene (CDKN2A), BRAF and PI3K mutations in pro-growth signaling pathways, and TERT gene mutations activating telomerase. Recognition of melanoma antigens activating immune responses has led to promising immunotherapy, enhancing host T-cell identification of these antigens.
The most common sites for melanoma metastasis include the lungs, liver, brain, bones, and regional lymph nodes, with bone metastases occurring in 25-50% of metastatic melanomas. The axial skeleton is more frequently affected by metastatic spread, causing pain and pathological fractures. The probability of metastatic spread depends on the primary tumor's stage, considering depth, mitotic activity, skin ulceration, and involvement of nodes and solid organs.
Diagnosis involves excisional biopsy, while investigation for bone metastasis utilizes blood tests (elevated alkaline phosphatase, calcium, and LDH) and radiological examinations, commonly X-rays and CT scans, with MRI and PET scans also being used. Treatment strategies depend on the tumor stage and immune profile, involving surgical resection, chemotherapy, immunotherapy, radiotherapy, or a combination of these approaches.
