Melorheostosis

 

Meleorheotosis 1Meleorheotosis 2Meleorheotosis 3

 

Definition

 

Melorheostosis - greek for "limb flowing bone formation"

 

Rare sclerosing bone dysplasia

 

Usually affects lower limb

 

Epidemiology

 

1: 1 000 000

 

Can be asymptomatic - 50% of persons affected will develop the symptoms by 20 years of age

 

Etiology

 

Random somatic mutations of the MAP2K1 gene

 

Clinical

 

Pain

 

Joint contractures - secondary to extraosseous bone formation

 

Leg length discrepancy due to growth plate involvement

 

Soft tissue masses

 

Nerve compression

 

Smith et al PMR 2017

- 23 cases of melorheostosis

- average age at first presentation 36 (range, 3 - 68)

- female:male 4:1

- 33% single bone, 67% multiple bones

- lower limb (67%), upper limb (33%), spine (17%), head (8%)

- pain (83%), deformity (54%), limitation of movement (46%), numbness (38%), and weakness (25%).

 

X-ray

 

Sclerotic lesions of bones 

- undulating cortical hyperostosis

- look like wax dripping down the side of a candle

 

Meleorheotosis Meleorheotosis 4

 

Meleorheotosis foot 1Meleorheotosis foot 2

 

Histology

 

Periosteal bone formation with dense cortical bone

Marked endosteal sclerosis with marrow fibrosis

 

Natural history

 

The clinical course is slowly progressive

 

Isolated cases of malignancy have been reported

 

Management

 

Nonoperative

 

Pain management

Bisphosphonates

 

Operative

 

Joint contracture release

Excision soft tissue tumours

Nerve release

Epiphysiodesis for growth-related abnormalities