S1640 Primary Colonic Lymphoma Manifesting as Colovesical Fistula

Abstract

INTRODUCTION: Gastrointestinal (GI) tract is the most common extranodal site of Non-Hodkin lymphoma (NHL) and constitutes about 4% of all GI malignancies. The most common sites of involvement in the GI tract are stomach followed by the small intestine. We report a case of primary colonic lymphoma manifesting with colovesical fistula in a patient with human immunodeficiency virus (HIV) infection. CASE DESCRIPTION/METHODS: A 50-year-old male with a history of HIV on antiretroviral therapy with undetectable viral load and a CD4 count of 260 cells/µL, presented with burning micturition, intermittent passage of air and feculent material in urine, on and off for one year. He has chronic nonbloody diarrhea and noticed thirty-pound weight loss over the past three months. At admission, he was afebrile, hypotensive, and had sinus tachycardia (114/min). Physical examination was significant for palpable, tender left lower quadrant mass but no hepatosplenomegaly, bowel distention, or peripheral lymphadenopathy. Laboratory data revealed anemia (HB 8.5 g/dl), leukocytosis (WBC 14000/µl), mildly elevated platelet count (422,000/µl), acute kidney injury (serum creatinine 2.50, baseline 0.81 mg/dL) and normal CEA level. Urine was brown, turbid with microscopy showing RBC and WBC ( >180/hpf). CT scan of abdomen and pelvis with contrast revealed a large circumferential mass measuring 14.5 cm × 10 cm in sigmoid colon with a fistulous communication to the urinary bladder suggestive of colovesical fistula. Colonoscopy confirmed a partially obstructing, large circumferential, ulcerated mass within the proximal sigmoid colon. Pathology was consistent with diffuse large B-cell lymphoma (+BCL2, +MYC). PET-CT scan showed increased FDG uptake in the sigmoid colon along with adrenal gland and bone but no involvement of lymph nodes, liver, or spleen. A diverting colostomy was performed and subsequently, he was started on dose-adjusted R-EPOCH Regimen. The patient received 5 cycles of chemotherapy and a repeat PET-CT scan showed resolution of activity in the sigmoid colon, bone, and adrenal gland. Retroperitoneal ultrasound during chemotherapy showed persistence of colovesical fistula. DISCUSSION: HIV-AIDS predisposes patients to different malignancies including NHL in about 10% of patients. Colonic involvement of primary NHL is exceedingly rare. High viral load and low CD4 counts (< 100) are risk factors for NHL in HIV patients. We describe here an unusual presentation of NHL manifesting as colovesical fistula, in a patient with HIV.Figure 1.: Computed tomographic scan of abdomen & pelvis in sagittal view showing large sigmoid mass (long arrow). Air-fluid level of orally administered contrast noted in the urinary bladder. (short arrow).Figure 2.: Colonoscopy shows a fungating, ulcerating mass in the sigmoid colon, nearly obstructing the lumen.Figure 3.: Initial PET tumor imaging whole body.