This course of the disease, with a strong subsequent acceleration of polyp development, may explain the wide range of polyp numbers counted in newly diagnosed MAP patients as a result of the time of observation. Therefore, MAP should also be considered in younger patients (35-55 years) with only few adenomas or colorectal cancer. The high frequency of medium and severe dysplasia in the patient's preferential small adenomas suggests accelerated progression from adenoma to carcinoma in MAP, but this observation must be confirmed by further studies.

MUTYH-associated disease, and hence genetic counselling and MUTYH genetic testing, should be considered in the clinical routine of an endoscopy unit, but the wide range of phenotypes represents a challenge for patient identification. The clinical significance of p.Q338H should be evaluated in future case-control studies because compound heterozygotes for pathogenic mutations and p.Q338H may be at increased risk for mild polyposis or CRC. In addition, MUTYH should be assessed as a potential susceptibility gene for the development of colitis-associated CRC in future.

A 46-year-old man with fluctuating abdominal pain and slight elevation of inflammatory markers (C-reactive protein 22.2 mg/L, normal <5) was referred for ileocolonoscopy after surgical evaluation including a non-diagnostic ultrasound examination. Endoscopy revealed an appendiceal orifice with profound intraluminal bulging (Picture 1A) and spontaneous purulent discharge as well as minor mucosal erythema (Picture 1B). The patient underwent an uneventful appendectomy including cecal pole resection. Final pathologic evaluation confirmed the presence of ulcero-phlegmonous appendicitis with accentuated involvement of the appendix base.The diagnosis of acute appendicitis is occasionally made by endoscopy in the presence of atypical symptoms and inconclusive imaging findings (1). In such a setting, endoscopic evaluation may help to rule out differential diagnoses, e.g. ileocecal tumors or inflammatory bowel disease (2). Endoscopic features include orificial buldging and edematous mucosal alterations. Sometimes, active putride secretion is present, potentially contributing to an attenuation of the clinical course.

Aim: Biallelic MUTYH germline mutations predispose to recessively inherited adenomatous polyposis, designated MUTYH-associated polyposis (MAP), and colorectal cancer (CRC).The hotspot mutations p.Y179C and p.G396D account for the majority of pathogenic variants in Caucasians. Our aim was to evaluate the prevalence of MUTYH mutations in clinical routine patients with different colorectal diseases. Method:The hotspot mutations p.Y179C and p.G396D were genotyped in 352 consecutive patients undergoing colonoscopy at our tertiary referral centre. Exons 2-14 were sequenced in hotspot mutation carriers to exclude additional variants.

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