Ectopic pseudarthrosis in fibrodysplasia ossificans progressiva

Fibrodysplasia ossificans progressiva (FOP) usually presents with episodes of ectopic and disabling ossification. American FOP specialists involved in a natural history protocol for this disease report six cases with an unusual presentation:

• clinical and radiological data from six patients with FOP, identified in the United States and Germany and presenting with pseudarthrosis, were collated,
• in addition to the classic signs of FOP (ectopic ossification progressing in episodes and bone malformations, particularly in the big toe), all patients had one or more pseudarthroses,
• which were comparable to pseudo-joints, with cartilage articulating with the newly formed bone.

Although these findings concern only a small number of patients, they provide a better understanding of the phenotypic expression of FOP.

Ectopic pseudojoints in fibrodysplasia ossificans progressiva. Pignolo RJ, Al Mukaddam M, Broski S et al. JBMR Plus. 2025 Jun