Visceral Malignant Melanoma: Wilderness of a Black Hole

Malignant melanoma (MM) is malignancy of melanocytes, with the commonest primary site being skin. Mucosal melanomas make less than 1% and prognosis is poor if not detected early. Identifying the primary lesion can be challenging and a small percentage of patients falls under the category of melanoma of unknown primary (MUP). We herein report a rare case of an 86- year- old male who presented with frank hematuria and multiple pigmented naevi over bilateral lower limbs. A Computed Tomography Urography (CTU) revealed a bladder tumour at lateral wall, which then proceeded with a transurethral resection of bladder tumour (TURBT). He was discharged well pending histopathological examination (HPE) report. He presented again with small bowel obstruction and a CT showed small bowel intussuscepting tumour with several lungs and right adrenal gland lesions requiring a laparotomy, small bowel resection and anastomosis. A black pigmented tumour was found to be a lead point of the intussusception. Patient recovered well from surgery and was discharged well. HPEs of both the surgeries revealed malignant melanoma, unable to identify the primary tumour. This case shows the notorious behaviour of MM to metastasize without symptoms. Coupled with the similar HPE of both sites of bladder and bowel, it makes it difficult to establish the primary site. CT imaging should be the mainstay choice of investigation to identify primary disease and evidence of metastasis. Initial management of MM should be complete surgical resection of suspected primary lesion. In the unfortunate event of patient developing distant metastasis, role of adjuvant therapy in visceral melanoma is evolving with clinical trials focusing on immunotherapy, tyrosine kinase inhibitors and dacarbazine.