MON-375 A Sporadic Case of Camurati-Engelmann Disease: A Rare Sclerosing Bone Disorder

Background: Camurati-Engelmann disease (CED)is a rare sclerosing bone disorder. The skull and the diaphyses of the long tubular bones are mainly affected. The symptom developed in childhood and patients suffer from bone pain, easy fatigability, and decreased muscle mass and weakness. CED is caused by mutations in the transforming growth factorβ1 (TGFβ1)gene on chromosome 19q13.113.3. This condition is inherited in an autosomal dominant pattern. Case: A 20- year-old male. He has a so-called marfanoid habitus with long and narrow limbs. At the age of 19,he presented pain in lower limb, then walking became difficult. None of his relatives had similar symptoms. In biochemical tests,calcium, Phosphorus and bone-related hormones levels were all in the normal range. 25(OH)vitamin D levels were low probably due to his eating habits. On radiological evaluation, X-ray showed thickening of the bone cortex of the bilateral tibia. Bone scintigraphy revealed markedly increased tracer uptake in the bilateral temporal bone, femur, and tibia. Based on clinical and radiological features CED was suspected. Sequence analysis of the transforming growth factor β1 (TGFB1)gene revealed a previously reported pathological variant (p.R218H). Discussion: CED is a rare pan-ethnic condition with more than 300 published cases worldwide. Although this case was difficult to diagnose because there was no family history and the onset of adulthood not childhood, this disease was suspected due to the typical localization of affected bone lesions by bone scintigraphy and was diagnosed by genetic testing. The majority of CED are missense variants in exon 4 leading to single amino acid substitutions in the encoded protein. Exon 4 encodes a latency-associated peptide (LAP) that suppresses the activity of TGF-β1 protein. No consensus management guidelines have been developed to date. Treatment with corticosteroids may relieve the pain, improve the muscle weakness and fatigue. Recently, the efficacy of losartan has been reported in some patients. Conclusion: Here we report a de novo case of CED diagnosed by genetic testing. Osteosclerotic diseases are very rare and are often difficult to diagnose. Genetic testing plays an important role in confirming the diagnosis.