Mesenteric Metastases from Cutaneous Malignant Melanoma - Erler Zimmer
Clinical History
A 44-year-old man presented with a slow-growing skin lesion on his back. Several years later, upon arriving at A&E, he complained of bone pain, exhibited hepatomegaly, and had a pleural effusion. Unfortunately, he passed away shortly afterward.
Pathology
The specimen, a loop of small intestine with displayed mesentery, reveals numerous small dark brown, circumscribed nodules ranging from pinhead size to approximately 1 cm in diameter. Histology confirmed the diagnosis of metastatic melanoma.
Further Information
The most common form of melanoma is cutaneous melanoma, originating from melanocytes, the pigment-producing cells. In women, they frequently occur on the legs, while in men, the back is a common site. About 25% of melanomas develop from moles, with changes such as increased size, irregular edges, color change, itchiness, or skin ulceration indicating potential melanoma.
Skin melanoma is linked to UV radiation exposure, either from sunlight or tanning beds. Risk factors include fair complexion, a large number of melanocytic nevi (moles), severe childhood sunburn, and immunosuppression. While constituting only around 5% of skin cancer diagnoses, melanoma has the highest mortality rate. Melanomas typically manifest in sun-exposed areas as pigmented lesions with irregular borders, varied color, asymmetrical shape, and evolving characteristics over time.
Multiple mutations are common in melanoma, including CDKN2A gene mutations affecting cell cycle control, BRAF and PI3K mutations in pro-growth signaling pathways, and TERT gene mutations activating telomerase. Recognition that melanoma antigens trigger host immune responses has led to promising immunotherapy, enhancing host T-cell identification of these antigens.
The lungs, liver, brain, bone, and regional lymph nodes are common sites for metastasis. Gastrointestinal involvement may present with complications such as anaemia, bleeding, pain, obstruction, or intussusception, with the jejunum and ileum being the most commonly affected sites. Surgery is usually reserved for complications.
The likelihood of metastatic spread from skin melanoma depends on the primary tumor's stage, considering depth, mitotic activity, skin ulceration, and node and solid organ involvement. Diagnosis involves excisional biopsy. Bone metastasis investigation includes blood tests (elevated alkaline phosphatase, calcium, and LDH) and radiological studies, often X-ray and CT, with MRI and PET scans as alternatives. Treatment varies based on tumor stage, genetic and immune profiles, involving surgical resection, chemotherapy, targeted therapies (e.g., BRAF inhibitors), immunotherapy, radiotherapy, or a combination of treatments.
