Enchondromatosis or multiple enchondromata is characterized by rounded masses of unossified cartilage in the metaphyses and diaphyses of certain bones, particularly the small bones of the hands and feet.
A rare variant of the condition in which enchondromatosis is associated with multiple cavernous haemangiomata and phleboliths in the soft tissue was described with Maffucci.
Enchondromatosis affects both sexes and has no hereditary predisposition. The condition is already present at birth when it may occasionally be noticed because of shortness of an affected limb. More usually a child presents with swelling of the fingers, deformity or shortening of a limb. In less severe cases, the presenting symptom may be a pathological fracture in adolescent or adult life.
The lesions represent a perversion of enchondral growth and are therefore confined to cylindrical bones. In mild cases, the lesions may be confined to one hand and there is a strong tendency to unilateral distribution of the lesions. Lesions affecting the more proximal bones are more extensive and vigorous in growth and the region of the knee joint and the lower end of the radius and ulna are particularly common sites.
When a single limb is affected, severe shortening may develop with associated deformity such as genu varum or valgum. In the hand enchondromata in the phalanges and metacarpal bones are very common and their increase in size may cause considerable loss of hand function.
Radiological Appearances
In the small bones of the hand, the lesions are globular and expand the bone so that the cortex becomes extremely thin and even perforates with external projection of the cartilaginous mass. Spotty calcification is often present in the enchondromatous lesions.
In the long bones, the lesions involve the metaphysic and extend into the diaphysis as elongated, translucent columns giving rise to a striated appearances which is pathognomonic. The metaphysial region is expanded but relatively undistorted in shape and the shaft is short and often thick and dense.
Sometimes a lesion projects towards the surface of the bone but such projections point towards the epiphysial line in contrast to those in osteochondromatosis which are always inclined towards the centre of the shaft. The epiphyses are at first normal but in older children they may show irregularity and mottling.
Metachondromatosis also shows multiple enchondromata, especially in the bones of the hands and feet, but differs in that the bone lesions tend to regress and the lesion is of dominant inheritance.
Progress
The increasing size of multiple enchondromata in hands interferes with movements of the fingers so that eventually the hand may become almost useless. Shortening, where lesions involve one lower limb, may be anything from 5 to 25 centimeters (2 to 10 inches) by the time growth is complete.
The tumours continue to grow slowly in adult life and may require multiple operative procedures to preserve function. The incidence of sarcomatous change varies widely in different series.
Chondrosarcoma is more likely to develop in a proximal bone though it can very rarely occur in the hand. Sarcomatous degeneration is mainly confined to cases of Maffucci’s syndrome.
Pathology
The lesions are essentially hamartomatous proliferations of cartilage cells within the metaphysic. The cells appear to be epiphysial chondroblasts which fail to mature properly and migrate into the metaphysis where they produce masses of useless disorganized cartilage cells which may closely mimic neoplastic chondromatous growth.
The cells vary from small chondroblasts to relatively mature large vacuolated chondrocytes in a totally disorderly pattern. There may be infiltration with amorphous calcium salts. The cause of the abnormality is not known; Rang (1969) suggests that an abnormality of vascular invasion of calcified cartilage leading to an accumulation of uncalcified cartilage may be responsible.
Treatment
Chondromata in affected phalanges and metacarpals can be curetted out and projections removed. If necessary, the cavities can be filled with autogenous or stored cancellous bone or cortical bone graft.
The multiplicity of lesions makes it impossible to tackle all of the affected regions in a severely involved hand and selection for operative treatment should be made of those bones that are interfering with finger movement. Sometimes a complete ray of the hand may need to be removed.
In the lower limbs, the main problem is likely to be shortening. If the limb inequality at the end of growth is likely to be less than 10 centimeters (4 inches), leg lengthening may be appropriate but if the shortening is very severe, amputation may be the only solution. Osteotomy may be required to correct deformity and the fragments unite readily.
A watch need to be maintained in adolescence and adult life for evidence of sarcomatous degeneration, especially in Maffuci’s syndrome. Rapid enlargement of a tumour, particularly in a bone close to the vertebral axis, pain, or radiological suspicion of malignant change is an indication for biopsy.
Even if sarcomatous change has not developed in an enlarged chondroma, partial removal may be needed at intervals because of discomfort, difficulty in dressing or the sheer weight of the excess chondroid tissue.
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