Melorheostosis

Melorheostosis:  A rare and progressive disorder characterized by hyperostosis of the cortical bone.  Melorheostosis is a mesenchymal dysplasia in which the bony cortex widens and becomes hyperdense in a sclerotomal distribution. As such, it tends to be unilateral and monoostotic. Melorheostosis affects both bone and soft tissue growth and development.   It can result in severe functional limitation, extensive pain, soft tissue contractures, and limb, hand, or foot deformity. 

Epidemiology:  The disease often presents between the ages of 5-20

Risk Factors: Unknown. The disease may be associated with neurofibromatosis and vascular malformations.

Symptoms: Patients may present with joint stiffness, pain, and deformity that may progress over time. The disease has rarely been reported in the skull, face, ribs, or spine. It is usually unilateral.

Differential Diagnosis: Osteopoikilosis, Osteosarcoma, Osteopathia Striata

Investigations: On plain radiographs, five patterns of melorheotosis have been characterized.  The classic pattern demonstrates thick undulating ridges of bone, also known as ‘dripping candle wax’.

Treatment: While no definite therapy exists, treatment modalities include analgesia and surgery to relieve contractures. At times, amputation is necessary as the disease is often progressive.

 




Case #1a. Melorheostosis predominantly affecting right upper hemithorax. The "dripping candle wax" appearance is classic. 

 



Case #1b. CT correlation of radiograph above. Note widened, hyperdense bone cortex of right upper ribs and right aspects of spine.