Alopecia: Clinical

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Alopecia: Clinical

USMLE® Step 2 questions

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USMLE® Step 2 style questions USMLE

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A 25-year-old woman comes to her primary care physician's office because of hair loss over the past two weeks. She has type I diabetes mellitus which is controlled with an insulin pump. She reports that her hairdresser noticed a "bald spot" on her scalp when she had her hair cut two weeks ago. Physical examination shows a well-circumscribed oval patch of hair loss in the occipital region with no evidence of scarring. The surrounding hair around the periphery is broken. Which of the following is the most likely diagnosis?


Alopecia refers to a loss of hair from part of the head or body and it can occur in a wide variety of disorders.

Assessment begins with obtaining a description of hair loss and the areas involved, as well as a medical history and family history.

Physical examination involves inspection of the scalp and other body sites.

Assessment of activity on the scalp may be done with a hair pull test, done by gripping about 20 hairs and gently pulling upward and away from the skin. Normally, about three hairs may fall out with each pull, while if more than 10 hairs are removed, the test is considered positive.

A noninvasive method of examining hair and scalp is trichoscopy, which is performed with the use of a dermatoscope. This traditionally consists of a magnifier, a non-polarised light source, a transparent plate and a liquid medium between the instrument and the skin.

In some cases, diagnostic techniques such as microscopic examination of cut or plucked hair fibers and scalp biopsies may provide additional information.

The pluck test is conducted by pulling hair out by the roots.

The root of the plucked hair is then examined under a microscope to determine the phase of growth, and is used to diagnose if there’s a defect of anagen or telogen.

Anagen hairs have sheaths attached to their roots, while telogen hairs have tiny bulbs without sheaths at their roots.

Finally, getting a scalp biopsy from the centre of the lesion gives confirmation of permanent hair loss, whereas a biopsy from the edge or an area of active inflammation may shed light on the underlying disease, and depending on the suspected diagnosis, additional laboratory studies may be performed.

Broadly, hair loss disorders can be divided into cicatricial or scarring alopecias, non scarring alopecias, and structural hair disorders.


Alopecia means hair loss, but it is not limited to the scalp as it can be anywhere in the body. For cosmetic reasons, patients may become concerned with hair loss, but it can also be an important clue to systemic disease. Common causes of alopecia include androgenic alopecia, drugs, infections such as tinea capitis, and trauma.


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