A Case of Neonatal Myositis Ossificans Related to Chronic Kidney Disease and Vitamin D Deficiency.

Myositis ossificans (MO) is currently defined as a self-limiting ossifying lesion affecting any extra-skeletal soft tissue type but mostly afflicting skeletal muscles. The pathogenetic mechanism of the disease is incompletely understood, especially in paediatric cases, and has been rarely described in neonates. Ossifying myositis related to chronic kidney disease (CKD) and vitamin D deficiency has been well documented in adults with CKD-mineral bone disease (CKD-MBD), but no paediatric cases have been described. Therefore, we describe a neonate with ossifying myositis following CKD and vitamin D deficiency, with complete remission after adequate treatment. An extremely premature neonate was admitted to our neonatal intensive care unit and presented with acute kidney injury and vitamin D deficiency in the first days of life. An x-ray and computed tomography scan detected muscle ossification of the iliopsoas, gluteus maximus and thigh muscles. Whole-body bone scintigraphy revealed a pathological increase in osteoblastic activity and a change in bone morphology and confirmed the persistence of muscle ossification after initial treatment. Treatment with alfacalcidol and cholecalciferol led to gradual clinical and laboratory improvement. A biopsy was not performed since the symmetrical lesions of the affected muscles confirmed by x-rays, CT and bone scintigraphy ruled out the suspicion of malignancy. So far, neonatal MO related to CKD has not been described in the literature stressing the diagnostic and treatment challenges.