Eyelash trichomegaly: review of congenital, acquired, and drug-associated etiologies for elongation of the eyelashes.

Eyelash trichomegaly is defined as eyelashes which are found to be of increased length, thickness, and pigmentation. This unique finding can be present at birth as part of a variety of congenital syndromes or as a benign familial trait. There are also acquired conditions and drugs that are known to cause these changes. Case reports and clinical studies in the medical literature concerning eyelash trichomegaly were investigated and summarized to compile a comprehensive review of the etiology of eyelash trichomegaly. Previously published reviews and studies that report on the finding of increased generalized hair growth and which do not specifically mention eyelashes were not included. Trichomegaly of the eyelashes may occur as a key feature among rare congenital syndromes, develop in association with certain acquired diseases, or present as an intended or treatment-related adverse drug effect. Eyelash trichomegaly may be present from birth or manifest later in life in association with acquired diseases or drug therapy. The relevance of this finding may be benign, however eyelash trichomegaly in some individuals can be a symptom for immune dysfunction or a clinical measure of response to drug therapy.