Bone Abstracts

Background: The clinical presentation and the clinical phenotypic characterization and the natural history of Fibrodysplasia Ossificans Progressiva (FOP) is diverse and the natural history of the disease is to certain extent different from one patient to another.

Methods: In a series of eleven patients age range from 0 to 16 years (eight girls and three boys), variable clinical presentations were the landmark of these patients. At birth, all our patients manifested short great toes in a valgus position. Marfan syndrome was the suggested diagnosis in three children aged 3–8 years and in two adult patients. A constellation of deformities such as torticollis, painful spine, and painful and marked limitation of the weight bearing zones were confusing with variable age of onset. Monophalangia associated with Marfanoid habitus, were also a prevailing clinical presentations.

Results: Our results were based up on the appearance of the earliest pathologic feature of FOP in correlation with the clinical presentation. In infants (0–1 year); three infants showed congenital hallux valgus and stiff spine have been encountered. In pediatric group (3–8 years); in this group Marfanoid habitus was the prevailing clinical picture, genetic tests showed no mutation in the FBN1 gene. Their prime presentation of progressive torticollis with simultaneous development of erythrematous subfascial nodules, most commonly located on the posterior neck and back. In pre and adult group (10–16 years); four patients presented with monophalangia associated with painful movements because of the progressive heterotopic ossification of the spine and the weight bearing zones and marked elevation of alkaline phsophatase. Genetic confirmation has been perfromed in five patients manifested the classical mutation of the ACVR1 gene. The rest of the patients were assessed via clinical and radiographic phenotepes.

Conclusion: The early recognition of FOP can be performed by noticing the short halluces and thumbs at early infancy and later on the high alkaline phosphatase activity in areas of heterotropic ossification. Misconception of FOP is of common practice and eventually unnecessary diagnostic biopsies might deteriorate the progression of the condition. The detection of ACVR1 gene mutation was a confirmatory procedure. Interestingly, the timing of the onset and the location of progressive heterotopic ossifications was extremely variable and confusing among our group of patients.