What is Melorheostosis?

Melorheostosis (also known as Leri disease) is a rare dysplasia manifesting as regions of sclerosing bone with a characteristic dripping wax appearance or flowing candle wax appearance

The disease, described by Leri and Joanny in 1922, is a rare, non-hereditary lesion.

Patients with melorheostosis may have associated

• Vascular malformations
• Neurofibromatosis
• Hemangioma
• Arterial aneurysms
• Linear scleroderma
• Tuberous sclerosis
• Hemangiomas
• Focal subcutaneous fibrosis.

Etiopathology

The cause of melorheostosis is unknown, but one theory proposed is that the lesion arises from an abnormality of the sensory nerve of the affected sclerotome.

[A sclerotome is a zone of the skeleton supplied by an individual spinal sensory nerve, and represents a basic unit of vertebral embryonic development.]

The disease may be

Monostotic – Involves single bone

Polyostotic – Several bones may be involved

When one limb is affected in several, usually contiguous areas, the disease is called monomelic.

Isolated cases of malignancy have been reported in association with melorheostosis.

The lesions of the cortex are progressive and may result in narrowing of the medullary canal and stenosis of an adjacent lumen, foramen, or of the spinal canal.

Motor or sensory nerves may be compressed.

Extension into the joints may cause loss of motion. Extensive soft tissue masses adjacent to the involved bone may develop. These masses may get ossified over the time.

Presentation of Melorheostosis

The features of the disease can be seen in early childhood and even in the first few days of life but the condition often remains occult until late adolescence or early adulthood.

About 50% of persons affected will develop the symptoms by 20 years of age.

In children, the condition affects mainly the bones of the extremities and pelvis and may result in limb length inequality, deformity, or joint contractures.

Adults generally complain of pain, joint stiffness, and progressive deformity.

Imaging of Melorheostosis

On x-rays, the lesions show undulating cortical hyperostosis [excessive bone growth]. The classic appearance is one of the thick undulating ridges of bone, reminiscent of molten wax

Radionucleotide uptake is markedly increased in affected bone areas.  The soft tissue lesions  show iv gadolinium enhancement

Treatment of Melorheostosis

The clinical course is slowly progressive occasionally resulting in substantial disability from contractures or deformity. Severe symptoms may require treatment by tendon release, osteotomy, sympathectomy or even amputation.