Tumor-Like Growth of Giant Inflammatory Polyposis in a Patient with Ulcerative Colitis
A 25-year-old Japanese man with an UC history of 2 years and 6 months was successfully treated with prednisolone. The disease was in remission and his symptoms had been relieved. However, the disease flared up and the patient was admitted to our hospital because of severe abdominal pain and bloody diarrhea. Physical examination revealed direct soreness and masses in the upper and left lower abdominal sites. Blood examination revealed anemia (hemoglobin level 5.5 g/dl [normal 11.5–15.0]), hypoproteinemia (protein level 4.6 g/dl [normal 6.7–8.3]) and hypoalbuminemia (albumin level 1.9 g/dl [normal 3.8–5.3]).\nComputed tomography (CT) imaging showed bowel wall thickening of the transverse and descending colon, which raised suspicion of wall thickening of several segments of the small bowel. The CT scan also demonstrated localized high-density areas in the lumen of the transverse and descending colon (fig. ). Barium enema examination showed irregular mucosal contours with polyposis in these areas (fig. ). A colonoscopy revealed a large mass with numerous white-pale reddish polyps of complex shape in the descending colon. The endoscope could not be inserted beyond this point. Endoscopy indicated that the colon distal to the mass and the rectum were normal. Based on this examination, colon carcinoma was strongly suspected, and several biopsies were performed. Histology of the examined sections indicated uncharacteristic inflammatory changes in the mucosa, but no cellular dysplasia. Subsequently, the patient underwent a total colectomy for removal of the obstruction. His postoperative recovery was complete, and he remains in good health.\nMacroscopic examination of the excised colon indicated remarkable dilation. On excision, we observed one tumor measuring 23 × 18 cm in the transverse colon and another measuring 14 × 13 cm in the descending colon. There were no obvious areas of ulceration, although each tumor had a coral-reef-like surface with numerous soft, finger-like polyps (up to 5 cm in diameter) projecting into the lumen. These aggregating polyps occurred in the segment with the thickened wall. The cross-section of the tumors showed that narrow strings of tissue were interconnected, forming multiple, variably sized spaces inside the tumors (fig. ). The surrounding fat tissue was unaffected, and no suspicious lymph nodes were detected.\nMicroscopic examination revealed that the tumors comprised strings of fibrotic connective tissue, lined by inflamed colonic mucosa, and the surrounding spaces were filled with fecal and mucoid materials. A fibrovascular core and inflammatory polyposis were evident from the submucosa to the proper muscular layer and the submucosa had partially disappeared in both the elevated and the depressed lesions. The polyps contained regenerative and hyperplastic muscularis mucosa with an arborized and thickened configuration (fig. ). In most areas, the crypt architecture was normal, and no epithelial atypia of the polyps was noted. The mucosal inflammation consisted of lymphocytes, plasma cells, eosinophils and lymphoid follicles. Neutrophil infiltration, cryptitis, crypt abscess, which is characteristic of active UC, and Paneth cell metaplasia were found in the transverse colon (fig. ). Sections through the bowel wall near the mass showed colonic mucosa with regenerative features, including architecturally mildly distorted glands, but without active inflammatory changes (fig. ). There were no granulomas or parasites. Finally, histopathological examination of the resected colon led to the diagnosis of giant inflammatory (filiform) polyposis associated with UC.