Melorheostose

Melorheostosis, also known as Leri disease, is an uncommon mesenchymal dysplasia manifesting as regions of sclerosing bone with a characteristic dripping wax appearance (a.k.a. flowing candle wax appearance).

Epidemiology

Although changes occur in early childhood, age at presentation is often later, and the condition often remains occult until late adolescence or early adulthood. In only approximately half of the cases is the diagnosis made before the age of 20 .

There is no recognized familial predisposition .

Clinical presentation

The condition, especially in childhood, is usually asymptomatic, being diagnosed as an incidental finding on radiographs obtained for another purpose . When melorheostosis does manifest clinically, the most common presentation is of joint contracture or pain, which are more common in adults .

Pathology

Distribution

Melorheostosis can be either monostotic or polyostotic and tends to be monomelic. It has a predilection for long bones of the limbs, although it can be seen almost anywhere. Hands and feet are not infrequently involved whereas involvement of the axial skeleton is rare . The condition has a tendency to give a sclerotome distribution. Uncommonly, it can present with a mineralized peri-articular mass.

Associations 

• sclerodermic skin changes: thickening and fibrosis of overlying skin
• hyperpigmentation of overlying skin
• muscle atrophy
• vascular tumors and malformations
• other tumors, e.g. osteosarcoma, malignant fibrous histiocytoma 
• Buschke-Ollendorff syndrome

Radiographic features

Plain radiograph

Radiographs are considered sufficient for establishing the diagnosis.

Five patterns have been described :

• classic
  • periosteal cortical thickening is characteristic, but endosteal thickening is also seen in many cases, especially when the age of onset is in adolescence, where it may be purely endosteal
  • thick undulating ridges of bone, reminiscent of molten wax (dripping wax appearance or flowing candle wax appearance)
  • confined to sclerotomes, and can be seen apparently flowing across joints to the next bone
• osteoma-like
• myositis ossificans-like
• osteopathia striata-like
• mixed

Not infrequently features of melorheostosis, osteopathia striata and osteopoikilosis may co-exist in a so-called overlap syndrome, termed mixed sclerosing bone dysplasia. These conditions may share an underlying etiology (loss of function mutations in the LEMD3 gene) .

MRI

Usually, the lesions show low signal on all imaging sequences, with no enhancement.

Nuclear medicine

An increase in radiotracer uptake is usually present on late phase bone scans .

Treatment and prognosis

The disease is of variable severity, but in general follows a chronic progressive course in adults and a faster course in children, occasionally resulting in substantial disability from contractures or deformity.

Conservative management is often unrewarding, and in severe cases, surgical intervention may be required, including tendon release, osteotomies and even amputation .

History and etymology

The condition was first written up in the literature by the French neurologist Andre Leri (1875-1930) and J Joanny in 1922 .

The name is derived from the Ancient Greek words for limb (melos) and flow (rhe), due to its characteristic appearance of flowing hyperostosis .

Differential diagnosis

Possible considerations include

• myositis ossificans
• osteoma
• focal scleroderma
• parosteal osteosarcoma
• Caffey disease
• sclerotic metastasis (e.g. breast and prostate)
• hypertrophic osteoarthropathy

Siehe auch:

• Osteom
• Osteopoikilose
• Myositis ossificans
• Osteopathia striata
• Buschke-Ollendorff syndrome
• Melorheostose der Schädelkalotte
• Ribbing-Syndrom
• monomelic
• linear morphea
• monostotisch
• polyostotisch
• dripping wax appearance
• Kerzenwachszeichen

und weiter:

• diffuse bony sclerosis (mnemonic)
• Osteopetrose
• conditions involving skin and bone
• radiologisches muskuloskelettales Curriculum
• osteoid lesions
• sklerosierende Knochendysplasien
• diffuse skelettale Sklerosierung
• calvarial melorheostosis
• Osteopoikilosis presenting with symptoms of Melorheostosis
• dripping candle wax sign
• monostotic melorheostosis