Melanotic Xp11-associated tumor of the sigmoid colon: A case report

Figure 1 The examination results of the patient. A and B: Preoperative computed tomography (CT) showing thickening of the rectal wall with edema; C: Postoperative CT showing a high-density suture shadow in the operation area; D: Approximately 32 cm inside the anus, a large mucosal bulge can be seen in the sigmoid colon. The surface was rough with local erosion. The tumor was brittle on biopsy and bled easily; E: Preoperative gastrointestinal angiography showing a filling defect at the junction of the sigmoid and the descending colon. The barium sulfate passed through, the local wall was stiff, and the mucosal destruction was interrupted; F: Pathological consultation at Xijing Hospital. The tumor cells in the muscle layer of the sigmoid colon were scattered in the nest, and capillaries were separated. The cytoplasm of tumor cells was rich and lightly stained. The nucleus was medium-sized and round or oval (note the nucleolus). The nuclear division was rare, and a small amount of pigment was visible. Immunohistochemistry showed that the tumor cells expressed a melanin marker and TFE3, accompanied by TFE3 gene translocation, consistent with pigmented Xp11-related tumors. Tumor cells were positive for TFE3 and Cathepsin, and fluorescence in situ hybridization (FISH) results showed TFE3 gene fragmentation (see the FISH report). Original immunohistochemistry results showed HMB45 (+), Melan-A (+), Ki-67 (+, approximately 5%), smooth muscle actin (-), CK (-), and EMA (-); G: Results of FISH test at Xijing Hospital shown that the TFE3 is fractured.