Odontogenic keratocysts in nevoid basal cell syndrome (Gorlin’s Syndrome). CT and MR evaluation

Introduction: The nevoid basal cell syndrome (Gorlin’s Syndrome) is a dominant autosomic disorder, characterized by multiple basal cell carcinomas, odontegenic keratocysts, dural calcifications, bone and face malformations, tumors including meduloblastoma and ovaric fibromas, as well as different degrees of mental retardation. Characteristic imagine findings of the Gorlin’s Syndrome are odontogenic keratocysts in the jaw and jawbone, prognathism, cleft lip and palate, macrocephalia, prominent paranasal cavithe documented presence of this syndrome in the patient’s family. The initial imaging workup included plain radiographs and Computed Tomography (CT) of the facial area and mandible, revealing large expansile cystic changes in the body and angle of the mandible, bilaterally (Figure 1). The expansile lesions were clearly intramedullary with erosion, thinning and scalloping of the endosteal cortical bone, without evidence of periosteal reaction. In general, the internal contents of the lesions were of low density and homogeneous, with a few scattered central calcifications within the mandibular cyst on the left side. No associated soft tissue mass was identified. Additional cysts were seen in the maxillary sinus, bilaterally and were larger on the right with bone remodeling and septation. There were non-erupted teeth within the cystic lesions in the maxilla on the left, as well as in the mandible on the right. Intracranially dural calcifications were noted in the falx. Magnetic Resonance Imaging (MRI) was performed for further assessment of the cystic lesions and to rule out intracranial abnormalities. T1 Weighted (T1W) and T2 Weighted (T2W) sequences and a post-contrast T1W sequence were obtained (Figure 2). Multiple expansile cystic lesions were again identified involving the mandibular angle and ramus bilaterally. Cystic lesions were also present in the maxillary sinus bilaterally, with greater involvement on the right, showing septation. The cystic contents were of low signal intensity on T1W sequences, and of high signal intensity on the T2W sequences, with some heterogeneous signal intensity, probably related to hemorrhagic components and a thin rim enhancement following Gadolinium administration. MR images of the brain demonstrated minimal thinning of the body of the corpus callosum. The lateral ventricles were slightly enlarged for the patient’s age. No abnormal enhancing brain parenchymal lesions, heterotopic gray matter, or brain tumor were identified. A plain film skeletal survey, including views of the scapulae, ribs, hands and lumbar spine were performed. All appeared unremarkable. Discussion Although CT is valuable in elucidating osseous craniofacial anomalies associated with NBCCS, MR is superior in demonstrating the internal composition and structure of the odontogenic keratocysts commonly seen in this syndrome CT imaging defined the cystic osseous expansion, septation and wall thinning. Aside from tooth primordia within the cysts, the contents appeared homogenous on CT, except for a few small densities, probably representing calcifications in the mandibular cyst on the left. MR illustrated the hyperintensity of the lesions on the T2W images indicating the cystic nature and contrast enhancement of the cystic lining the postcontrast T1W images. The imaging findings in the mandible and maxillae are consistent with odontogenic keratocysts, characteristic ties, inter-hemispheric bone calcifications, vertebrae malformations (cifoescoliosis and abnormal segmentation), ribs merging, short forth metacarpian and sclerotic bone lesions. Material and methods: A case of a 13-year old male patient is presented, with family background of Gorlin’s Syndrome who presented mouth fetid serum-bloody drain, prognathism and hypertelorism. Imaging studies showed bi-lateral cystic lesions on the jaw’s angle and maxillary antra. MRI with T2 and T1 powered images with Gadolinium showed multiple cystic lesions with lobe-like contours, which had their peripheral contour highlighted after the administration of Gadolinium, some with a secondary liquid level at hemorrhagic component. Brain MRI showed minimum slimming of the callous body and a small prominence of the ventricle system for his age. The bone series did not show any alterations different from those already described. Discusion: Even though the CT is useful in diagnosing face abnormalities related to Gorlin’s Syndrome, MRI is better in it capacity to show the internal composition and the structures of odontogenic keratocysts.