Primary malignant melanoma of the small bowel: A case report

Abstract

Malignant melanoma comprises 1%-3% of all malignant tumors of the gastrointestinal tract. The small bowel melanoma is an extremely rare malignancy. Very few cases have been reported in the literature. The small intestine is mostly affected by the metastatic tumors of the primary lesions especially cutaneous. This malignancy is diagnosed at the late stages as the patient remains asymptomatic. In this report we present a case of malignant melanoma arising from the small bowel in a 58-year-old male. There was no primary lesion in the eye, skin, anus, rectum or elsewhere in the body. The patient was treated with surgery. Afterward the patient presented to the emergency room with respiratory distress for which he was on ventilator support, sadly the patient died after 10 days. Malignant melanoma is an aggressive tumor and does not respond well to chemotherapy or radiotherapy.

Keywords: Aggressive tumor; Gastrointestinal Radiology; Malignant melanoma; Oncoimaging; Small intestine malignancy.

Fig. 1

Primary malignant melanoma of the small intestine: noncontrast CT showing hypodense lesion with no evidence of intratumoral calcification or hemorrhage (A) axial (B) coronal.

Fig. 2

Primary malignant melanoma of the small intestine: contrast enhanced CT axial showing heterogeneously enhancing lesion with areas of hypodensity suggesting necrosis.

Fig. 3

Primary malignant melanoma of the small intestine: contrast enhanced CT, showing heterogeneously enhancing lesion with areas of necrosis in mid abdomen on right side (A) coronal, superior mesenteric vein is normally visualized, (B) sagittal, fat plane with the right kidney is maintained.

Fig. 4

Primary malignant melanoma of the small intestine: 18FDG PET-CT shows peripheral pathologic FDG uptake in the lesion with FDG nonavid central necrosis.

Fig. 5

Primary malignant melanoma of the small intestine: 18FDG PET-CT shows pathologic FDG uptake in the solid component of the lesion (A, B), as well as in the margin of the lesion (C, D).

Fig. 6

Primary malignant melanoma of the small intestine: (A): Hematoxylin & Eosin (H&E) stained section showing tumor arranged in form lobules, nests and sheets, 100x; (B): Hematoxylin & Eosin (H&E) stained section showing round to polygonal tumor cells with coarse chromatin, prominent nucleoli and moderate cytoplasm, 400x; (C): HMB45 immunostaining showing granular cytoplasmic positivity in tumor cells, 400X; (D) S100 positivity in tumor cells, 200x.