An angiomatous nasal polyp (ANP) is a relatively rarely diagnosed disease which is not often mentioned in the professional literature. Due to its histological picture it can be mistaken for an angiofibroma (juvenile or extranasopharyngeal). The authors evaluate a group of 13 patients operated on account of a sinochoanal polyp from the aspect of histological changes suggesting an ANP and present the case-record of a 12-year-old boy with this disease diagnosed and treated at the ENT Clinic of the Vinohrady Faculty Hospital and Third Medical Faculty Charles University. The patient suffered for several months from left-sided obstruction with relapsing epistaxis which even called for a blood transfusion. Clinically the tumour gave the impression of a typical antrochoanal polyp and was completely removed froman endonasal approach without major haemorrhage.With regard to the clinical properties, easy surgical removal and marked secondary changes of the histological picture the original diagnosis of the pathologist - extranasopharyngeal angiofibroma - was reevaluated and changed to ANP. ANP develops most probably due to repeated traumatization most frequently of sinochoanal polyps (in particular antrochoanal) but may develop also in other types of nasal polyposis. The resulting neovascularization and fibrosis can lead to mistaking of ANP for an angiofibroma. In the differential diagnosis of these two diseases it is important to take into consideration the clinical properties of the tumour, the results of imaging examinations (CT, MR, angiography) and the result of the histological examination. This is the reason why in the diagnosis and treatment of this disease collaboration of an otorhinolaryngologist, pathologist and specialist in imaging methods in important.

        Key words: antrochoanal polyp, angiofibroma, nasal polyposis.