Scalp nodules as a presenting sign of fibrodysplasia ossificans progressiva: A register-based study

BackgroundFibrodysplasia ossificans progressiva (FOP) is a rare genetic disorder characterized by progressive ossification of soft tissues. Clinical diagnosis is important because trauma from lesional biopsies can exacerbate the disease.ObjectiveWe sought to evaluate the frequency of scalp nodules as the presenting manifestation of FOP.MethodsWe describe 3 infants with FOP who presented with multiple neonatal scalp nodules. We reviewed all 43 cases of this disorder in the French FOP registry.ResultsScalp nodules were found in 40% of cases and usually represented the first manifestation of the disease. All 43 patients had characteristic skeletal malformations involving the great toes (n = 43), fingers (n = 12), and vertebrae (n = 3). Other abnormalities were cerebral malformations (n = 1) and alopecia (n = 2). Histopathologic analysis did not contribute to the differential diagnosis and was interpreted as cranial fasciitis in two patients.LimitationsOur study was retrospective, and the presence or absence of scalp nodules was not always recorded.ConclusionNeonatal scalp nodules associated with a characteristic malformation of the great toes are a common presentation of FOP. Physicians should be aware that lesional biopsies can exacerbate the disease and must therefore be avoided. A diagnosis of classic FOP can be confirmed by molecular genetic studies.