Localized hypertrichosis of intermammary cleft in monozygotic twins.

Hypertrichosis is a condition in which hair is longer and denser than what is considered normal for an individual based on age, sex, ethnicity, and location on the body and can be classified based on its distribution (generalized vs localized), age of onset (congenital vs acquired), and type of hair (lanugo or vellus vs terminal). We describe a rare case of monozygotic female twins who presented for localized hypertrichosis of the intermammary cleft that developed during puberty. Endocrine examination was unremarkable. Discussion of various treatment modalities should be considered, because localized hypertrichosis may have a considerable psychosocial effect.