Hypertrichosis cubiti (hairy elbow syndrome): a clue to a malformation syndrome.

Hypertrichosis cubiti (HC) or hairy elbow syndrome (OMIM # 139600) consists of a localised form of long vellus hair on the extensor surfaces of the distal third of the upper arm and the proximal third of the forearm bilaterally, or occasionally on other parts of the body. In the 28 cases reported in the literature so far the elbow hair abnormality was either isolated or associated with short stature or other physical abnormalities. Most of these cases were sporadic, but autosomal dominant as well as autosomal recessive inheritance patterns have been postulated. We report on three unrelated girls (aged 7 to 11 years) of whom one presented with excess hair in the elbows alone and the other two had associated abnormalities including short stature, dysmorphic facial features and mental retardation. The literature on this subject has been reviewed and the authors focus on cases of HC with associated anomalies. A pathogenic explanation by somatic mosaicism is proposed.