||Hypertrichosis lanuginosa acquisita (HTLA) is the term applied to the excessive growth of fine hair of the lanugo or vellus type. Medications such as phenytoin, streptomycin, penicillamine, and minoxidil have all been reported on occasion to produce this unusual phenomenon. Metabolic conditions including porphyria, pregnancy, hyperthyroidism, and malnutrition have also occasionally been associated with HTLA.
Hypertrichosis lanuginosa acquisita has also been associated with the presence of malignant disease. It is interesting to speculate upon the role that HTLA involving the pinna, and associated with porphyria, may have played in the origin of the "werewolf" myth.