CT of malignant melanoma: patterns of small bowel and mesenteric involvement.

Abdominal CT of 230 patients (310 CT examinations) with a diagnosis of malignant melanoma was retrospectively reviewed for the evaluation of small bowel and mesenteric involvement. Seventeen (7.4%) patients had evidence of small bowel and mesenteric involvement on CT. There were four distinct patterns of disease: (a) intraluminal masses in 3 patients; (b) ulcerating lesions in 2; (c) diffuse infiltration in 6; (d) implants in 10. Four patients had more than two patterns of involvement. Of the 10 patients with tumor implants, carcinomatosis was noted in 2. Two patients had intussusception and 4 had extensive mesenteric nodal involvement. Of the 17 patients, 12 (71%) had at least one symptom referable to the gastrointestinal tract, while 5 (29%) were clinically asymptomatic. Fourteen of the 17 patients (82%) had additional intraabdominal metastases to sites other than small bowel and mesentery.