Hair in the middle phalanges: clinical significance.

Middle phalangeal hair has been a focus of study in different populations for the absence or presence of this trait. Clinically, this is often perceived as a solely cosmetic feature. However, because of a series of patients questioning the presence of hair on this location, we have performed a more in-depth literature-based evaluation of the trait. The goal of this manuscript was to examine the clinical significance of this anthropological phenomenon. A literature review was performed that focused on the differences of this trait in terms of pattern of presentation, age, race, sex, and usage as an identifiable marker for medical significance in certain medications and criteria for tailored treatment. Anatomically, middle phalangeal hair is mostly on the fourth finger and more ulnar rather than central or symmetric in pattern of deviation. Its presence has been most associated with high prenatal androgen exposure, predisposing patients to suffer from adverse side effects from oral contraceptives. Phalangeal hair may be helpful in tailoring treatment to certain patients from different ethnic backgrounds, and particularly in individuals with unknown ancestry.