What is Melorheostosis?

Last Updated on February 2, 2025

Melorheostosis is a rare benign, painful disorder of the extremities characterized by the formation of periosteal new bone leading to a wax-like appearance of the bone.  It was first described by Andre Leri (1875-1930)  and J Joanny. The term is derived from melos+rhe [limb+flow in Greek] due to its characteristic appearance of flowing hyperostosis.

Melorheostosis is a rare condition that affects fewer than one million people in the world. About half of the patients are seen before the age of 20.  Both genders are equally affected though some recent studies indicate female preponderance.

Though the changes occur in early childhood, the condition remains occult until late adolescence or early adulthood.

There is no recognized familial predisposition

Melorheostosis typically manifests in the limbs. Typically, the condition is often limited to one limb but generally affects more than one bone [polyostotic].

Melorheostosis and osteopoikilosis may co-exist in a so-called overlap syndrome, also called mixed sclerosing bone dysplasia. There may be a common etiology here involving LEMD3 gene).

Associated Conditions

Patients with melorheostosis may have associated

• Overlying skin hyperpigmentation
• Vascular malformations
• Neurofibromatosis
• Hemangioma
• Linear scleroderma
• Tuberous sclerosis
• Hemangiomas
• Focal subcutaneous fibrosis.
• Muscle atrophy
• Tumor like osteosarcoma, malignant fibrous histiocytoma
• Buschke-Ollendorff syndrome

Causes

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 time.

Various theories proposed to explain causation

• Gene Mutation theory
  • MAP2K1 gene-  dripping candle wax form
    • leads to gradual deterioration of bone microarchitecture that causes such periosteal reaction
  • SMAD3-  endosteal form
  • LEMD3 gene- Familial cases [linked to other dysplasia like osteopoikilosis]
• Vasomotor neurosis
• Congenital abnormality

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.

Lab Investigations

Serum calcium, phosphorus, and alkaline phosphatase levels are normal.

Imaging

X-rays

On x-rays, the lesions show undulating cortical hyperostosis [excessive bone growth]. The classic appearance is one of the thick undulating ridges of bone similar to the appearance of molten wax or dripping wax flowing along the cortex of the bone.

Five patterns have been described

• Classic
  • Periosteal cortical thickening –  characteristic
  • Endosteal thickening may be seen esp in late-onset cases
  • Dripping wax appearance or flowing candle wax appearance
• Osteoma-like
• myositis ossificans-like
• Osteopathia striata-like
• mixed

Scintigraphy

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

Biopsy

It is done only in cases where there is confusion in diagnosis or as part of a surgical procedure.

Treatment

Non-operative Treatment

This is considered for patients with mild symptoms and minimal stiffness.

Bisphosphonates have been shown to be effective in easing pain and swelling. Other nonoperative approaches are

• Virtual reality (VR) therapy
  • harnesses computer-generated environments to provide immersive experiences aimed at pain relief
  • Various mechanisms
    • Cognitive distraction
    • Visuotactile stimulation
    • Visuomotor stimulation
• Physical therapy
  • Stretching exercises
  • Regular periods of daily activity
  • Splinting
  • Strengthening exercises for muscle weakness

Operative Treatment

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. Repetitive surgery may be needed especially in children.

References

• Melorheostosis: a review of the literature and a case report. Iordache S, Cursaru A, Serban B, Costache M, Spiridonica R, Cretu B, Cirstoiu C. Medicina (Kaunas) 2023;59:869. doi: 10.3390/medicina59050869. [Link]
• Which treatment protocol is better in the rehabilitation of joint contracture? Tecer D, Ya?ar E, Ad?güzel E, et al. Gulhane Med J. 2020;62:14–20.
• Physical therapy during in-patient rehabilitation for a patient with Stiff-Person syndrome. Potter K. J Neurol Phys Ther. 2006;30:28–38. doi: 10.1097/01.npt.0000282147.18446.b8.
• Neuromuscular electrical stimulation for muscle weakness in adults with advanced disease. Jones S, Man WD, Gao W, Higginson IJ, Wilcock A, Maddocks M. Cochrane Database Syst Rev. 2016;10:0. doi: 10.1002/14651858.CD009419.pub3.