Inflammatory Colonic Polyp as a Manifestation of Neurofibromatosis Type 1

Figure

a) Endoscopic image showing an inflammatory polyp in the cecum. b) Histologic image of the inflammatory polyp (hematoxylin and eosin stain, x40 magnification) showing prominent vessels and a dense inflammatory infiltrate with eosinophilia

A 44-year-old female patient with known neurofibromatosis type 1 (NF1, Recklinghausen’s disease) presented to our central emergency department with perianal bleeding. The patient had a history of malignant peripheral nerve sheath tumor (MPNST) with pulmonary metastases, which had been treated with pazopanib. Colonoscopy revealed an inflammatory polyp in the cecum that was considered a potential source of bleeding and was resected with a cold snare. Histology confirmed the polyp to be inflammatory. Next-generation sequencing (NGS) demonstrated a PIK3CA mutation. Inflammatory polyps are described in the literature as rare but specific gastrointestinal manifestations of NF1. Histologically, the appearance of these polyps varies, ranging from juvenile-like to inflammatory or hyperplastic changes. The PIK3CA mutation identified in this case has also been described as typical in this context, and the PIK3CA–mTOR pathway is known to be overstimulated in NF1. Perianal bleeding resolved completely following polypectomy.

Dr. med. André Sasse, Prof. Dr. med. Philipp Ströbel, Dr. med. Christoph Ammer-Herrmenau, Klinik für Gastroenterologie, gastrointestinale Onkologie und Endokrinologie, Universitätsmedizin Göttingen, [e-mail]

Conflict of interest statement: The authors state that no conflict of interest exists.

Translated from the original German by Christine Rye.

Cite this as: Sasse A, Ströbel P, Ammer-Herrmenau C: Inflammatory colonic polyp as a manifestation of neurofibromatosis type 1. Dtsch Arztebl Int 2026; 123: 183. DOI: 10.3238/arztebl.m2025.0171