Systemic Mastocytosis the Great Mimicker - a Rare Haematological Neoplasm Presenting With Diarrhoea, Anaphylaxis and Rash

Aims: Background Eosinophilic Gastrointestinal Disorders (EGIDs) cause gastrointestinal symptoms with eosinophilia (biochemically and histologically). A history of anaphylaxis raises suspicion that Systemic Mastocytosis (SM) is the rare yet highly likely differential. In these rare cases, serum tryptase levels with tissue staining for c-kit (histological marker of mast cells) confirms the diagnosis since mast cells/eosinophils are indistinguishable on routine histological stains. SM, a haematological neoplasm characterized by accumulation of clonal mast cells in systemic tissues, causes debilitating symptoms.

Methods: Case presentation A 59-year-old caucasian female presented with acute bloody diarrhoea (ten episodes over two days). Her comorbidities included: eosinophilic enterocolitis and urticaria pigmentosa – previously diagnosed on colonic/skin biopsies for workup of chronic diarrhoea with generalized macular-papular rash. CT initially revealed enlarged (> 2cm) small bowel mesenteric lymph nodes non-specifically reactive on biopsy. Her past medical history included anaphylaxis to anti-inflammatories. Biochemically she had persistent peripheral eosinophilia. Recently, CT showed stable nodes, and colonoscopy revealed cobblestone mucosa suggestive of crohn’s colitis. Histological impression, however, was in keeping with eosinophilic enterocolitis. Serum tryptase, requested to identify any unifying aetiology for cutaneous mastocytosis and systemic symptoms, was persistently elevated. To corroborate, restaining of histological specimens for mast cells showed c-kit positivity.

Results: Diagnosis SM, in this case, diagnosed by fulfilment of one minor (serum total tryptase > 20ng/ml) and one major (> 15 mast cells in aggregates in extracutaneous tissues) criterion of the WHO guidelines.

Discussion EGIDs have protean manifestations and are diagnosed when symptoms of gastrointestinal dysfunction are accompanied by histological eosinophilia after exclusion of other differentials. Beyond the standard differentials for EGIDs, a history of anaphylaxis and skin manifestations might allude to the diagnosis of SM.

Conclusions Gastrointestinal manifestations of SM are a rare yet easily treated cause of persistent gastrointestinal dysfunction. Our patient had cessation of gastrointestinal symptoms on combined H1/H2 antihistamines.

Citation: Muller TL, Van Der Merwe K, Said A etal. eP298 SYSTEMIC MASTOCYTOSIS THE GREAT MIMICKER - A RARE HAEMATOLOGICAL NEOPLASM PRESENTING WITH DIARRHOEA, ANAPHYLAXIS AND RASH. Endoscopy 2021; 53: S196.

Publication History

Article published online:
19 March 2021