Malignant gastrointestinal melanomas of unknown origin: Should it be considered primary?

Figure 1 An abdominal CT scan section showing an obstructive luminal mass at the jejunum proved to be of melanotic nature.

Figure 2 Melanoma of the small intestine with submucosal infiltration. Numerous pleomorphic tumor cells with melanin deposits are viewed (HE, x 250).

Figure 3 Colonic malignant melanoma originated at the anorectum (HE, x 100).

Figure 4 Melanoma of the small intestine stained with Masson-Fontana. Plenty of granules of melanin are viewed (x 100).

Figure 5 Melanoma of the small intestine stained with HMB-45 (x 100).

Figure 6 Surgical specimen of a segmental enterectomy for a primary melanoma located at the jejunum. A few lymph nodes of the mesentery proved to be infiltrated.