INDOLENT SYSTEMIC MASTOCYTOSIS MASQUERADING AS CHRONIC ANEMIA IN ULCERATIVE COLITIS: A CASE STUDY

Abstract

Abstract BACKGROUND Anemia is a frequent systemic/extra-intestinal manifestation of inflammatory bowel disease (IBD). It has a complex multifactorial etiology which suppresses erythropoiesis due to pro-inflammatory mediators, myelosuppression, iron and micronutrient deficiency. It significantly impacts quality of life (QoL) and increases hospitalizations, length of hospital stays and mortality rates. It Is commonly thought to arise as a consequence of IBD or it’s related therapy. Current strategies are aimed at correction of anemia with low priority towards identifying a specific cause. Here, we represent a case of UC with chronic anemia secondary to systemic mastocytosis (SM). CASE A 41 y/o female with UC presents to the outpatient clinic with complaints of fatigue. Further questioning revealed a baseline of 1-2 formed bowel movements per day. She did not report any hematochezia or weight loss. She was managed on 300 mg of vedolizumab every 4 weeks. Prior failure to medications includes anti-tumor necrosis factor inhibitors and tofacitinib. Labs were consistent with albumin 4.5 mg/dL and CRP < 1 mg/dL. Iron studies revealed low iron, TIBC and ferritin levels. Fecal calprotectin measurements were not available due to patient non-compliance. Patient (Pt) was thought to have experienced a UC flare and colonoscopy was recommended. Colonoscopy was unrevealing with no sign of active disease on examination (Mayo Endo 0). Pt was referred to hematology where she underwent a bone marrow biopsy revealing multifocal dense infiltrates of mast cells (≥15 mast cells in aggregates) expressing CD2+ and CD 25+ with 25% showing atypical morphology in bone marrow biopsies. KIT D816V mutation was also positive. The serum tryptase level in this pt was 47.1ug/L. She was then placed on anti-histamines, proton pump inhibitors and steroid therapy. CONCLUSION SM is a clonal disorder of MC that infiltrates one or more organs. It almost always involves the bone marrow. Gastrointestinal (GI) symptoms are present in up to 80% patients. These symptoms are secondary to systemic effects of MC mediators. Incidence of SM in UC has never been established. SM has been shown to mimic Crohn’s disease and is difficult to differentiate based on clinical and endoscopic features. Furthermore, little is known regarding histopathological features of GI involvement in SM. The presence of chronic anemia despite adequate therapy in a clinically/endoscopically inactive UC patient should raise suspicion of other pathologic causes of anemia. Our case highlights the importance of diagnosing the specific cause of anemia in IBD as it may lead to inaccurate clinical judgements of disease flares leading to undue alteration in therapy.