macrodystrophia lipomatosa

Macrodystrophia lipomatosa is a rare form of localized gigantism, and many terms have been used interchangeably, with resulting confusion. They include macrodactyly, megalodactyly, digital gigantism, macromelia, partial acromegaly, macrosomia, and limited gigantism .

It is worth noting that macrodystrophia lipomatosa is essentially analogous to static localized gigantism (as described by Barsky in 1967) .

Epidemiology

Macrodystrophia lipomatosa is a congenital but non-hereditary and is usually identified in the neonatal period .

Clinical presentation

This condition typically presents with painless enlargement of the 2 or 3 digit of the hand or foot.  It is usually unilateral but may involve adjacent digits in the distribution of the median or plantar nerves. Occasionally it involves the entire limb .

Pathology

Macrodystrophia lipomatosa is characterized by a marked increase in all mesenchymal elements . This is dominated by adipose tissue in a fine fibrous network involving periosteum, bone marrow, nerve sheath, muscle, and subcutaneous tissue.

Associations

Recognized associations include:

Radiographic features

Plain radiograph

Plain films usually suffice and demonstrate splayed, lengthened and broadened phalanges with endosteal and periosteal bone deposition.

The overlying soft tissues are markedly overgrown, especially in the volar and distal aspects. Within the soft tissues, focal lucent areas representing fat may be seen, which is characteristic.

MRI

MRI is helpful in distinguishing macrodystrophia lipomatosa from other causes of macrodactyly (see below). It demonstrates accumulation of fat in the subcutaneous tissues without a discernable capsule . There might be fibrous strands seen withing this accumulated fat with cortical thickening, osseous hypertrophy and bony outgrowths from the underlying bone. Neural thickening may also be visualized.

Treatment and prognosis

Although macrodystrophia lipomatosa is considered a progressive form of macrodactyly (i.e. the growth of the affected parts is faster than the rest of the body) growth halts at puberty .

As such treatment is reserved for cosmesis and when the mechanical function is impaired.

History and etymology

The term was first coined in 1925 by Hans Feriz (1895-1970), a German physician .

Differential diagnosis