Metastatic Melanoma Presenting as a Massive Abdominal Mass with Lower Extremity Radiculopathy

Abstract

Purpose: The purpose of this case report is to highlight the unusual and often vague presentations of melanoma metastatic to the abdomen. Case: A 63 year old male with past history of prostrate cancer and surgically resected left arm melanoma, presents with left lower extremity pain and weakness, one month after finishing brachytherapy for prostrate cancer. In the following months patient was evaluated for sciatica, claudication and DVT with normal doppler studies and x-rays of the lumbar spine and pelvis. The lower extremity parasthesias and paresis progressively worsened in this 8 month period requiring the patient to use a cane for ambulation. Patient also had 40-lb weight loss with anorexia but no other gastrointestinal complaints. At admission the abdominal exam revealed a large palpable mass extending from the midline to the left flank. Catscan of abdomen/ pelvis revealed a massive 11×14 left abdominal mass with multiple nodular masses in the mesentery. FNA biopsy showed a poorly differentiated non-small cell carcinoma with following immunochemistry: HMB-45: positive Vimentin: strongly positive S-100: focal weak positive PSA: negative CK7: negative Cytokeratin: negative The above findings were consistent with metastatic melanoma. An MRI of the spine done for worsening paraparesis showed cauda equina compression requiring radiation therapy. However the patient was unable to undergo further treatment due to his deteriorating clinical status and succumbed to complications of the malignancy. Discussion: Malignant melanoma metastastic to the abdomen has a clinical diagnostic rate of just 2%, in contrast to 60% of autopsies that are found to have gastrointestinal involvement in patients that died with disseminated disease. Most cases of metastatic melanoma to the gastrointestinal tract present with vague symptoms of weakness, fatigue, abdominal pain and anemia. Our case report is very unusual in that it presented as a huge abdominal mass with mesenteric invovlement and lower limb radiculopathy. It also highlights the need for early imaging which is effective in ascertaining the extent of disease and the potential benefit of surgery as complete resection of metastasis is associated with prolonged survival. Conclusion: The presentation of melanoma metastatic to the gastrointestinal tract is vague and requires early investigation of symptoms as curative surgery can prolong survival.