Colonic ulcer as an uncommon finding of mastocytosis

An 87-year-old male in oncology follow-up after a surgically treated gastrointestinal stromal tumour (GIST). The follow-up CT scan revealed concentric wall thickening in the ascending colon (Fig. 1). Tests were completed with colonoscopy, where a circumferential ulcerated lesion was identified in the caecum (Fig. 2). Pathology examination revealed the presence of oval cells with central rounded nuclei and metachromatic cytoplasm compatible with mast cells infiltrating the lamina propria and demonstrating CD117 immunoreactivity (Fig. 3). Despite these findings, due to the patient's underlying disease, it was decided not to continue the study of systemic mastocytosis (SM).

Figure 1.

Abdominal CT: concentric wall thickening in the ascending colon.

Figure 2.

Endoscopic findings: ulcerated and circumferential lesion in the caecum.

Figure 3.

Pathology: A and B) Haematoxylin and eosin ×10 and ×40: mucosa with thickening of the lamina propria, cellularity with broad rounded, basophilic nuclei. C) C-kit (CD117) ×20: cytoplasmic immunohistochemical staining with virtually total inflammatory cellularity (mast cells).

Mastocytosis is a rare disease that can affect the skin exclusively (cutaneous mastocytosis) or multiple organs (systemic mastocytosis).

Around 70–80% of patients with SM are found to have gastrointestinal involvement.

Endoscopic findings vary from nodular involvement to pigmented areas, thickened folds or even a normal study. However, our case atypically presented with an ulcerated lesion.¹

There are studies that question whether mast cell aggregates in the bowel mucosa in asymptomatic patients have any systemic significance.^2,3 We should therefore interpret this histological finding with caution in order to avoid unnecessary medical procedures.