Endoscopic findings of the colon in a patient with systemic mastocytosis

A 69-year-old man with a five-year history of a skin rash was diagnosed with mastocytosis from a skin biopsy and had been under regular follow-up by a dermatologist. The patient was referred to us due to persistent diarrhea. Lower gastrointestinal endoscopy revealed edematous mucosa with many small, white, nodular mucosal lesions from the cecum to the sigmoid colon (Fig. 1a). Endoscopy with image-enhanced, narrow-band imaging easily located the white elevated lesions, the surface of which revealed uniformly sized dark spots (Fig. 1b). Biopsy specimens of the flat, white bulges revealed that the lamina propria was infiltrated with mononuclear cells and some eosinophils (Fig. 2a). The mononuclear cells were immunohistochemically positive for CD117 (Fig. 2b), indicating the involvement of mastocytosis in the colon.

Fig. 1

Fig. 2

Mastocytosis is defined as the overgrowth and accumulation of mast cells, and when it involves sites other than the skin, it is regarded as systemic. Endoscopic findings of the colons of patients with systemic mastocytosis have shown various types of nodular lesions, aphthous ulcers and apparently normal mucous membranes. Image-enhanced endoscopy clearly identified the lesions in our patient. Due to the relatively high frequency of gastrointestinal symptoms, endoscopy should be actively considered when systemic mastocytosis is suspected.

Authors’ contribution

RM and YK wrote the manuscript and YK is the guarantor, IK and RS performed endoscopy, YF provided the images, MK managed patient care, SB concluded the pathological diagnosis, and MT edited the manuscript.

Prior presentation

None.

Informed consent

The patients provided written, informed consent to the publication of this report.

Conflicts of interest

None.