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Localised macrodystrophia

Localised macrodystrophia or gigantism is a rare, non hereditary tumour of the hand or foot. Macrodystrophia lipomatosa is one of its common causes which can be differentiated from conditions like neurofibromatosis, hemangiomatosis, lymphangiomatosis and Klippel-Trenaunay Weber syndrome by detailed clinical history and thorough physical examination. It is characterised by an increase in all the mesenchymal elements, particularly the fibro-adipose tissue and is more common in the foot with a predilection for the plantar nerve. In the hand, it is often associated with fibrolipomatous hamartoma of the median nerve(1). In the present communication, the authors report a case of macrodystrophia lipomatosa along the distribution of the digital branches of the median nerve. The condition was also associated with the syndactyly of the macrodystrophic middle and ring fingers.

 

Macrodystrophia lipomatosa,

a nonhereditary form of localized gigantism of unknown cause marked by congenital and progressive overgrowth of all the mesenchymal elements of a digit and disproportionate increase in the fibroadipose tissue. The increase in adipose tissue involves bone marrow, periosteum, muscles, nerve sheaths and subcutaneous tissues. Nerves may also be enlarged and irregular. Both endosteal and periosteal depositions of bone are responsible for phalangeal enlargement. This developmental disorder is recognizable at birth.

The foot is affected more commonly than the hand. Usually involvement is unilateral, with the favoured sites in both upper and lower extremities being the second and third digits. Local anomalies (syndactyly, polydactyly, clinodactyly) are very frequent.

On radiographs abnormalities are observed in both soft tissues and bone (Fig.1). Overgrowth of soft tissues is most prominent in the distribution of the median and plantar nerves, at the distal end of the digit and along its volar aspect. Small lucent areas may be present where overgrowth of fat occurs in the soft tissues. Late in childhood, secondary degenerative joint disease develops.

Other imaging techniques such as CT scanning and MR imaging may demonstrate large linear radiolucent bands of fat within the affected muscle.

Neurofibromatosis produces the most difficulty in differential diagnosis, but generally the radiographic findings can allow differentiation of macrodystrophia lipomatosa from neurofibromatosis.

Macrodystrophia lipomatosa, Fig. 1

AP (a) and lateral (b) radiographs of the foot in a 1-year old child demonstrate marked overgrowth of the second and third toes. Also note the hypertrophy of the soft tissues along the plantar aspect of the foot. (Courtesy of Richard Stiles, MD, Atlanta, GA)

 

Twelve-year-old female patient presented with hypertrophy of second toe of right foot since birth and was gradually increasing in size (Fig. 1). There was no family history of hypertrophy of limbs, no history of pigmentation and seizures. The patient was otherwise normal. X-ray foot revealed localized gigantism of right second toe and its digits, there was hypertrophy of fibroadipose tissue of right second toe. (Fig. 2). A diagnosis of Macrodystrophia lipomatosa was made.

Fig. 1. Macrodystrophia lipomatosa of second toe of right foot

Macrodystrophia lipomatosa is a congenital form of macrodactyly seen at birth. It is a progressive condition characterized by an increase in mesenchymal elements, especially the fibro adipose tissue. The abnormality is always unilateral, and usually in the distribution of the median nerve (upper extremity) and the planter nerve (lower extremity). Secondary degenerative arthro-pathy may be evident in young adults and limitation of joint movement is associated. Radiographic examinations demonstrate macrodactyly including the soft tissue and the bone. The trabeculae are normal. T1-weighted coronal MR image shows marked prolifera-tion of the adipose tissue. A high signal linear structure with low signal rim along the involved area may correspond to a thickened nerve.

Fig 2. X-ray of right foot showing 2 - localized gigantism of 2nd metatarsal and digits and lipomatosis around it

Macrodystrophia lipomatosa should be differentiated from other causes of congenital macrodactyly e.g., lymphangioma, heman-gioma, Klippel-Trenaunay-Weber syndrome, Ollier’s disease and Proteus syndrome.

 

                    
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