S3967 A Case of Mistaken Identity: Candida glabrata Mimicking Colon Cancer

Introduction: Colorectal adenocarcinoma is a feared cause of colon mass and the basis of colorectal cancer screening. While large, ulcerated colonic masses are usually malignant, benign lesions can also mimic adenocarcinoma. We present a case of a circumferential, ulcerated cecal mass presumed to be adenocarcinoma, but was ultimately diagnosed as a fungal infection. Case Description/Methods: A 75-year-old man with a history of chronic anemia presented with worsening anemia, with hemoglobin declining from 11.7 g/dL to 5.1 g/dL (normal range: 14.0-18.0 g/dL) and new-onset thrombocytopenia with 4 K/mm3 (normal range: 130-400 K/mm3). He was asymptomatic except for an episode of epistaxis. Hematology was consulted and he was diagnosed with immune-mediated thrombocytopenia and started on intravenous immunoglobulin and prednisone. After one unit of packed red blood cells his hemoglobin rose from 5.1 to 5.9 g/dL. Abdominal computed tomography showed thickening of the ascending colon and cecum. Colonoscopy revealed a large, partially obstructing mass in the ascending colon extending into the cecum, suspicious for malignancy. Biopsies showed acute inflammation and ulceration, were PAS-positive for Candida, but revealed no malignancy. Infectious disease was consulted and systemic fungal markers (serum Fungitell, galactomannan, and urine histoplasma antigen) were negative. Despite the biopsies not showing evidence of malignancy, sampling error remained high on the differential and a repeat colonoscopy was performed. Repeat biopsy showed inflammation and granulation tissue and no evidence of malignancy. Fungal cultures grew Candida glabrata. After a multidisciplinary discussion, the patient was diagnosed with a fungal inflammatory mass and started on a prolonged course of oral fluconazole. Follow-up colonoscopy is planned in 3 months to assess treatment response. Discussion: This case illustrates a cecal mass that initially appeared consistent with malignancy but was ultimately diagnosed as a fungal mass. Though rare, fungal infections can present as colon masses and are generally associated with invasive fungal disease, such as histoplasmosis. This case of Candida glabrata presenting as a colonic fungal mass highlights the importance of maintaining a broad differential diagnosis for colon masses. It also emphasizes the importance of collaboration and a multidisciplinary approach, as multiple specialties ensured thorough evaluation and management of a rare case.