Atlanto-occipital ligament calcification: a novel sign in nevoid basal cell carcinoma syndrome.

BACKGROUND The nevoid basal cell carcinoma syndrome (NBCCS), first described by Gorlin and Goltz in 1960, is a hereditary autosomal dominant disease with high penetrance and variable expressivity. Almost 70% of patients with NBCCS have some degree of craniofacial anomaly. Among these, the presence of ectopic calcification have been reported but Atlanto-occipital ligament calcification has never been described. Therefore this investigation was carried out to determine the prevalence of atlanto-occipital ligament calcification on lateral x-ray of NBCCS patients aiming to assess the effectiveness of this sign in NBCCS diagnosis. PATIENTS AND METHODS Lateral and frontal cephalometric radiographs of 18 patients (11 males and 7 females), aged 8-61 years, with the diagnosis of NBCCS were evaluated for the presence of intracranial calcifications (diaphragma sellae and falx cerebri) and or calcification of the atlanto-occipital ligament. RESULTS A total of 11 patients presented calcification of atlanto-occipital ligament to various degrees and in three cases this represented the only sign of ectopic calcification. When compared to the other two sites of ossification, atlanto-occipital ligament calcification had a similar prevalence. CONCLUSION The calcification of the atlanto-occipital ligament should be considered in addition to the other major criteria for NBCCS diagnosis.