Sudden-Onset Polyposis in Pediatric Patients With Ulcerative Colitis.

Abstract

To the Editors: Inflammatory polyps may develop in 10% to 20% patients with inflammatory bowel disease (IBD).1 However, such patients are mostly adults, and polyps rarely develop in children. Filiform polyps are extremely rare in children with ulcerative colitis (UC).2 Herein, we present a case of sudden-onset filiform polyposis during UC treatment in an 11-year-old girl. Low-grade dysplasia was histopathologically confirmed in another single polyp; therefore, this case underlines the importance of evaluating the heterogeneity of inflammatory polyps in pediatric patients with UC and follow-up of such patients. A 9-year-old girl presented with severe anemia and hematochezia. Her blood test findings were as follows: white blood cell count, 12 620/μL (eosinophils, 10.3%); hemoglobin, 6.4 g/dL. Her QuantiFERON-TB test result was negative; furthermore, she tested negative for cytomegalovirus, herpes simplex virus, fluorescent antinuclear antibody, Clostridium difficile, and antineutrophil cytoplasmic antibodies. Her immunoglobulin E level was 260.5 IU/mL (reference range, <158 IU/mL). Moreover, her fecal calprotectin concentration was over 6000 mg/kg. Colonoscopy showed a severe UC flare-up throughout the colon. She was initially treated with corticosteroids, azathioprine, and 5-aminosalicylic acid; however, there was no symptom improvement. After 4 months, infliximab (5 mg/kg) was administered; however, diarrhea and hematochezia persisted. Her fecal calprotectin concentration was 2000 to 5000 mg/kg. Infliximab trough level and anti-infliximab antibody were 0.1 μg/mL and 25.3 ng/mL, respectively. Therefore, infliximab was discontinued, and intermittent steroid treatment was continued with cyclosporine as the main drug. Although there was no acute exacerbation of UC, complete remission could not be achieved. Colonoscopy performed 15 months later yielded findings similar to those obtained in the previous one. After 18 months, polyps that had not been seen before suddenly appeared in the form of filiform polyposis in the transverse colon (Figure 1A). Biopsy findings revealed inflammatory polyposis (Figure 1B). A single polyp (sized approximately 3 cm) was observed in the sigmoid colon (Figure 1C); histopathological examination showed low-grade dysplasia (Figure 1D). The patient underwent diagnostic exome sequencing; APC gene mutation or other IBD- or immune deficiency–related mutations were not detected. Tumor marker levels and positron emission tomography computed tomography findings indicated no evidence of malignancy in other organs.