Adult Onset Hair Casts: Nits Which Do Not Itch

Hair casts (HCs) are firm, whitish cylindrical concretions that ensheath the hair shaft and can be easily dislodged. They are often misdiagnosed due to their resemblance to pediculosis capitis, also known as head lice. This case study reports a 22-year-old male patient with androgenetic alopecia who also had HCs on his scalp and body hair. His sister was similarly affected. HCs are of two types: parakeratotic and nonparakeratotic peripillar casts. The former is more common and often coexists with scalp conditions like psoriasis and seborrheic dermatitis. The latter is less common and not associated with any disease or scalp condition. HCs are often underdiagnosed due to their resemblance to pediculosis capitis. The patient's HCs reduced after using a salicylic acid-containing shampoo but did not completely disappear. The study concludes that HCs are benign and not associated with any morbidity, but their resemblance to other conditions often leads to diagnostic confusion.