Skeletal dysplasias encompass a heterogeneous group of over 400 disorders. They are individually rare, but collectively common with an approximate incidence of 1/5000; thus, radiologists occasionally encounter skeletal dysplasias in daily practice. However, many radiologists and trainees struggle with this topic because of the lack of proper resources. A group of skeletal dysplasias that share similar radiological patterns has been grouped into a “skeletal dysplasia family” which generally have common pathogenesis. For example, a skeletal dysplasia family comprising mucopolysaccharidosis, oligosaccharidosis, and mucolipidosis all radiologically exhibit dysotosis multiplex, and all share an abnormality in lysosome dysfunction. The beauty of this family concept is its simplicity and power. First, it allows a more systematic approach to the chaotic world of skeletal dysplasias – a stepwise approach, with the first step of general pattern recognition and categorization of a certain case into a certain family, and the second step of diagnosis based on more meticulous observations for subtle but distinctive radiological findings. Since major skeletal dysplasia families are limited in number, the radiologist can become familiar with their patterns. Second, radiographs can predict the presence of genetic mutations. Geneticists or pediatricians would appreciate the correct radiological diagnosis even in today’s genetics practice with advanced molecular techniques. Radiological diagnosis and genetics are complementary. Third, it may lead us to a more precise assessment of radiological findings. Shared findings among family members allow more accurate characterization of the severest end of the family which occasionally look similar to the one with different pathogenesis. The purpose of this exhibit is to demonstrate the imaging characteristics of major skeletal dysplasia families and the stepwise approach to the diagnosis. We will review the classic and more recently established dysplasia families. In addition, we will review clinical and genetic features that help radiologists to participate in multidisciplinary care. Introduction – Dysostosis multiplex family – FGFR3 (achondroplasia) family – COMP family – Type II collagenopathies – TRPV4 (metatropic dysplasia) family – Skeletal ribosomopathies – DTDST (diastrophic dysplasia) family – Linkeropathies – Filaminopathies A and B – Punctata group – Skeletal ciliopathies – Osteogenesis imperfecta group Read More

Meeting name: SPR 2022 Annual Meeting & Postgraduate Course , 2022

Authors: Handa Atsuhiko, Nishimura Gen

Keywords: Skeletal dysplasia

A term “ciliopathy” represents a diverse group of genetic disorders caused by mutations in genes coding for components of the primary cilia. Primary cilia have a pivotal biological role in the cell surface of nearly every organ system of the body. "Skeletal ciliopathy" is a subset of ciliopathy mainly affecting the skeleton and shares common radiological findings such as short ribs, short limbs, and short digits with or without polydactyly. Pattern recognition approach is thus useful to diagnose skeletal ciliopathy. Skeletal ciliopathy includes (1) Jeune asphyxiating thoracic dysplasia, (2) Ellis-van Creveld syndrome (chondroectodermal dysplasia), (3) Sensenbrenner syndrome (cranioectodermal dysplasia), and (4) Short rib-polydactyly syndromes. Clinically, affected patients commonly present with thoracic hypoplasia with respiratory failure and disproportional stature with a normal trunk and short limbs most severe in the distal segments. Brachydactyly is conspicuous. Patients may have extra-skeletal anomalies such as retinopathy, cardiac anomalies, cerebellar malformations, and hepatorenal failures. Radiological diagnosis of bone dysplasia might be regarded as something complex. We aim to highlight a pattern recognition approach to diagnose skeletal ciliopathies, one of the major bone dysplasias, by providing many cases. We will also review a general concept of "bone dysplasia family" which refers to a grouping of radiologically similar skeletal disorders into a “family.” This concept has been widely accepted now after we found that phenotypic similarities usually indicate the same/similar pathogenetic mechanisms, and it supports the use of a pattern recognition approach. Imaging diagnosis can guide genetic testing, interpretation, and possibly identify new genes or mutations. Read More

Meeting name: SPR 2019 Annual Meeting & Postgraduate Course , 2019

Authors: Handa Atsuhiko, Nishimura Gen

Keywords: Bone Dysplasia, Ciliopathy

Fetal CT has almost the same utility as a postnatal skeletal survey. Despite this benefit, the associated radiation exposure is disadvantageous and radiation dose reduction is mandatory. It is however impossible to measure the actual radiation dose to the fetus directly. Several previous reports have described the CT dose index (CTDI) volume and dose length product (DLP) as representing an imagined fetal dose. The actual fetal radiation dose needs to be confirmed using a phantom that practically corresponds to a pregnant woman. Read More

Meeting name: SPR 2019 Annual Meeting & Postgraduate Course , 2019

Authors: Miyazaki Osamu, Sawai Hideaki, Yamada Takahiro, Murotsuki Jun, Horiuchi Tetsuya, Nishimura Gen

Keywords: skeletal dysplasia, fetal CT, radiation dose