Calvarial melorheostosis: an extremely rare case and diagnostic challenge.

Melorheostosis is a rare bone disease that presents as sclerotic lesions growing on existing bone surfaces. This disease is of unknown etiology and affects both genders equally. The disease is unique in appearance, described in the literature as having a radiologic appearance of flowing candle wax, and usually occurs in the appendicular skeleton. We present an extremely rare case of melorheostosis of the calvarium in a 55-year-old male patient, initially thought to represent a large osteoma, and discuss the CT and MRI features, pathology, and surgical management. Recently, new insights have been gained by molecular biologic studies into the potential pathogenesis of this disease indicating genetic mutations, which will be discussed. This case report will help radiologists arriving at the correct diagnosis for an unusual manifestation of a rare disease.