[The interesting case: Nora's lesion of the big toe].

"Bizarre parosteal osteochondromatous proliferations" are extremely rare manifestations first described by Nora and only a few more than 100 cases have been described in the international literature. In spite of clinically resembling an osteochondroma, a subungual exostosis or a parosteal osteosarcoma, the lesion is characterised by distinct radiological and histological findings. The lesion is defined as a reactive heterotopic ossification and is mostly found in the hands and feet of adults in the third decade of life. A high rate of local recurrence of up to 50% has been described, but since it is defined as a benign lesion no metastases can be found. We report the instructive case of a BPOP ("Nora's lesion") in the area of the proximal phalanx of the big toe in which, after performing a biopsy, a resection of the lesion under preservation of the big toe was performed. At the last follow-up examination (4 years postoperatively) the patient showed no sign of recurrence of the lesion. The clinical, radiological and MRI appearance of the lesion are described together with the distinct clinical findings.