A Case of Intestinal Mastocytosis Misdiagnosed as Crohn's Disease

Abstract

Systemic mastocytosis (SM) is a rare, heterogeneous and progressive disease, characterized by the accumulation of atypical mast cells in various organs, including the gastrointestinal tract. Gastrointestinal symptoms are present in up to 80% of patients with SM, the most common being abdominal pain, diarrhea, nausea and vomiting. Up to 50% of patients with SM do not have classical skin lesions at presentation, and in these patients the diagnosis of SM can be difficult for years. Here we report a case of SM that initially mimicked inflammatory bowel disease, although the patient showed poor response to steroid therapy. The right diagnosis was made only on the surgical specimen obtained after emergency surgery for intestinal obstruction. SM should therefore be considered in the diagnostic approach in patients with gastrointestinal symptoms not attributable to other pathologies and in cases of suspected inflammatory bowel disease with unusual course.

Keywords: Crohn's disease; Differential diagnosis; Gastrointestinal symptoms; Systemic mastocytosis.

Fig. 1

Hematoxylin and eosin stain of random sampling in the colon with chronic inflammation and a conspicuous number of intramucosal mast cells.

Fig. 2

Immunoperoxidase stain for CD117. The stain reveals mast cells with strong membrane and cytoplasmic reaction (an example is highlighted by the arrow). In particular, more than 20 mast cells per high-power field are visible in the figure, in accordance with the major diagnostic WHO criteria.