title: Osteochondromas in fibrodysplasia ossificans progressiva: a widespread trait with a streaking but overlooked appearance when arising at femoral bone end.
abstract: Metaphyseal bony outgrowths are a well-recognized feature of fibrodysplasia ossificans progressiva (FOP) phenotype, but its genuine frequency, topographic distribution, morphological aspect, and potential implications are not fully established. To better ascertain the frequency and characteristics of osteocartilaginous exostoses in FOP disease, we conducted a cross-sectional radiological study based on all the traceable cases identified in a previous comprehensive national research. Metaphyseal exostoses were present in all the 17 cases of FOP studied. Although most often arising from the distal femoral (where metaphyseal exostoses adopt a peculiar not yet reported appearance) and proximal tibial bones, we have found that they are not restricted to these areas, but rather can be seen scattered at a variety of other skeletal sites. Using nuclear magnetic resonance imaging, we show that these exophytic outgrowths are true osteochondromas. As a whole, these results are in agreement with data coming from the literature review. Our study confirms the presence of metaphyseal osteochondromas as a very frequent trait of FOP phenotype and an outstanding feature of its anomalous skeletal developmental component. In line with recent evidences, this might imply that dysregulation of BMP signaling, in addition to promoting exuberant heterotopic ossification, could induce aberrant chondrogenesis and osteochondroma formation. Unveiling the molecular links between these physiopathological pathways could help to illuminate the mechanisms that govern bone morphogenesis.
authors.affiliation: Rare Disease Research Institute (Instituto de Investigación de Enfermedades Raras - IIER), Carlos III Institute of Health (Instituto de Salud Carlos III - ISCIII), Monforte de Lemos, 5, 28029, Madrid, Spain. amorales@isciii.es.|Consortium for Biomedical Research in Rare Diseases (Centro de Investigación Biomédica en Red de Enfermedades Raras - CIBERER), Madrid, Spain. amorales@isciii.es.
authors.forename: A
authors.identifier: http://orcid.org/0000-0002-5894-3592
authors.initials: A
authors.lastname: Morales-Piga
authors.affiliation: Rheumatology Department, Ramón y Cajal University Hospital, Madrid, Spain. fbachiller@gmail.com.
authors.forename: J
authors.initials: J
authors.lastname: Bachiller-Corral
authors.affiliation: Orthopedic Surgery Children's Unit, "Teresa Herrera" Mother and Child Hospital, A Coruña, Spain. pgonher@gmail.com.
authors.forename: P
authors.initials: P
authors.lastname: González-Herranz
authors.affiliation: Rheumatology Department, Miguel Servet Hospital, Saragossa, Spain. mmedrano@unizar.es.
authors.forename: M
authors.initials: M
authors.lastname: Medrano-SanIldelfonso
authors.affiliation: Rheumatology Department, San Carlos University Clinic Hospital, Madrid, Spain. franciscojavier.olmedo@salud.madrid.org.
authors.forename: J
authors.initials: J
authors.lastname: Olmedo-Garzón
authors.affiliation: Department of Molecular Cell Biology, Leids Universitair Medisch Centrum (LUMC), Leiden, The Netherlands. G.Sanchez_Duffhues@lumc.nl.
authors.forename: G
authors.initials: G
authors.lastname: Sánchez-Duffhues
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D005266:Femoral Neoplasms / Q000150:complications / Q000000981:diagnostic imaging* / Q000473:pathology; D005269:Femur / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009221:Myositis Ossificans / Q000150:complications / Q000000981:diagnostic imaging* / Q000473:pathology; D015831:Osteochondroma / Q000150:complications / Q000000981:diagnostic imaging* / Q000473:pathology; D011859:Radiography; D055815:Young Adult
keywords: Chondrogenesis; Exostoses; FOP; Fibrodysplasia ossificans progressiva; Osteochondroma