Short Anagen Hair With Persistent Synchronized Pattern of Scalp Hair Growth

The document describes a case of a 4-year-old boy who exhibited an unusual pattern of hair growth and shedding, characterized by synchronized waves of hair growth and a short anagen phase, which is the active growth phase of hair follicles. Unlike the typical asynchronized pattern of hair growth seen in humans, where each hair grows and sheds independently, this boy's hair growth was synchronized, similar to molting patterns seen in lower mammals. Despite having good scalp hair density, he had not required a haircut until 2.5 years of age due to the short length of his hair, which only grew a few millimeters to about 1 to 2 cm at the frontal hairline and occipital area, with longer hairs of about 5 to 10 cm in the midscalp region. The boy's condition did not fit into known hair disorders that involve a short anagen phase, and the persistence of synchronized hair waves had not been previously reported. The study suggests that the mechanisms controlling the duration and pattern of hair growth may be related or identical.