Posterior fossa horns; a new calvarial finding of mucopolysaccharidoses with well-known cranial MRI features

Abstract

Background/aim: Mucopolysaccharidoses (MPS) are a group of hereditary metabolic diseases. The aim of this study was to share thepreviously unreported calvarial finding of internal hypertrophy of the occipitomastoid sutures (IHOMS) together with some other wellknown cranial MRI findings in this patient series.Materials and methods: A retrospective evaluation was conducted of 80 cranial MRIs of patients who had been diagnosed and followedup with MPS from 2008 to 2019 in our center. Of these patients, 11 had Hurler, 14 had Hunter, 24 had Sanfilippo, 15 had Morquio, 14had Maroteaux–Lamy, and 2 had Sly disease. The cranial MRIs were assessed in two main groups as parenchymal intradural cranial MRIfindings and extradural calvarial findings.Results: The most common parenchymal intradural cranial MRI findings were white matter signal alterations (n = 51, 63%) andperivascular space enlargements (n = 39, 48%). The most common extradural calvarial findings were J-shaped sella (n = 45, 56%) andtympanic effusion (n = 44, 55%). Although IHOMS was defined in a relatively small number of the patients (n = 12, 15%), the prevalencerate was high in MPS type I (n = 6, 54%).Conclusion: The abnormal cranial MRI findings of the MPS patients, including the newly identified IHOMS, may provide diagnosticclues to differentiate the type of the disease in radiological imaging.