[Patients with a therapy-resistant anal fissure: beware of malignancies].

In this article we describe three patients aged 53, 39 and 70 with a therapy-resistant anal fissure. Each patient was inspected under anaesthesia. In all three cases a suspicious lesion or swelling was observed and all biopsies taken showed anal malignancies. Although anal malignancies are rare, their incidence has increased significantly over the past 22 years in the Netherlands (from 71 patients in 1989 to 215 in 2012). It is important to be aware of the possibility of malignancies among patients with a therapy-resistant anal fissure. Therefore, we recommend performing an inspection under anaesthesia in these patients to obtain tissue for histological analysis.