There seems to be no satisfactory clue to the causation of these abnormalisms.

Most frequently the left side is the least developed, and there is a decided difference in the size of the extremities.
Finlayson reports a case of a child affected with congenital unilateral hypertrophy associated with patches of cutaneous congestion.

Logan mentions hypertrophy in the right half of the body in a child of four, first noticed shortly after birth; Langlet also speaks of a case of congenital hypertrophy of the right side.

Broca and Trelat were among the first observers to discuss this anomaly.
Tilanus of Munich in 1893 reported a case of hemihypertrophy in a girl of ten.

The whole right half of the body was much smaller and better developed than the left, resulting in a limping gait.