What is the Differential Diagnosis of Localized Hair Loss?
A 14 year-old male came to clinic with a history of a round area of hair loss on the back of his head for a few days. There is itchiness and some flaking.
He denies hair loss or pruritis elsewhere on his body, and denies hair pulling. He finished wrestling season 2 weeks ago.
The past medical history is negative for chronic medical conditions or psychological stressors.
The family history is positive for androgenetic baldness. There are no immunologic diseases in the family.
The pertinent physical exam shows a healthy male. On the left side of the occiput there is a 3.5 centimeter in diameter, well circumscribed lesion with incomplete hair loss.
There are some broken hairs in the lesion and there is scaling at the ends of the lesion. There are no other areas on his scalp or body.
The diagnosis of of tinea capitus was made and he was placed on Griseofulvin for 6 weeks. He is to return if the scaling has not resolved and if the hair has not begun to grow back.
Hair is an epidermal apendage. There are 3 types of hair:
Lanugo hair – soft, fine hair shed at ~ 36-37 weeks of fetal gestation.
Vellus hair – fine, short hair covering most of the body. It replaces lanugo hair.
Terminal hair – long, course hair mainly in the scalp, pubic and axillary areas.
Hirsuitism is when vellus hair turns more into terminal hair. Androgenetic baldness is when terminal hair turns more into vellus hair. Some areas of the body remain free of hair such as palms, soles, mouth, and genitals.
Normal hair loss is ~50-100 hairs lost/day on the scalp. Normal hair grows about 2.5 mm/week.
The differential diagnosis of localized hair loss includes:
- Congenital syndromes – such as congenital triangular alopecia which has frontotemporal areas of alopecia.
- Alopecia areata – localized hair loss, usually round or oval in shape with no inflammation, often found on the scalp or beard, but also eyelashes, eyebrows, etc. Immune mediation may be the cause. Most resolves in a few months but may have more than one attack and subsequent attacks have less chance of complete resolution.
- Androgenetic alopecia – diffusely thinner scalp hair especially in the center of the scalp, sometimes with frontal accentuation. Course may be gradual or rapid. The cause is genetic but inheritance mode is unclear. Treatment includes wigs, hair transplants, medication such as Minoxidil or Finasteride or antifungal medication. Many people simply ignore it.
- Trichotillomania – irregular hair that is broken, bent and of variable length. Caused by conscious or subconscious plucking or pulling of the hair. Usually this is a minor comfort habit. Treatment is through stress control, possibly with psychiatric help if severe.
- Traction alopecia – irregular areas of short broken hair. It is caused by pulling or stress the hair with grooming including straightening, rolling, clipping, etc. of the hair. Treatment involves changing styling habits.
- Friction alopecia – generally rounded area that is prone to rubbing. This commonly occurs on the occiput of infants who lie on their backs. Treatment involves placing the infant in other positions.
- Tinea capitus – roundish area with scaling of the lesion, possibly with central clearing. Broken hairs may be seen.
It is caused by fungal infection of the scalp and hair, often seen in children 2-10 years old.
A Wood’s lamp examination may show fluorescence with Microsporum species (often associated with dogs and cats). Tinea caused by Trichophytons species do not fluoresce.
Treatment is a systemic antifungal such as Griseofulvin, Terbinafine or Intraconazole, as the fungus is in the bulb of the hair shaft and cannot be effectively treated topically.
Questions for Further Discussion
1. What are the side effects of Griseofulvin?
2. What is the differential diagnosis of non-localized hair loss?
To Learn More
To view pediatric review articles on this topic from the past year check PubMed.
To view current news articles on this topic check Google News.
Hurwitz S. Clinical Pediatric Dermatology, 2nd Edit. W.B. Saunders and Co. 1981:481-495.
American Academy of Pediatrics. Tinea Capitus, In Pickering LD, ed. Red Book: 2003 Report of the Committee on Infectious Diseases. 26th edit. Elk Grove Village, IL: American Academy of Pediatrics; 2003;617-618.
Donna M. D’Alessandro, MD
Associate Professor of Pediatrics, Children’s Hospital of Iowa
September 12, 2005