Can a biopsy showing AGA be wrong?

Can a biopsy of AGA be wrong?

I'm often asked if a biopsy can be 'wrong.' The short answer is that yes, a biopsy can potentially be wrong. Biopsies are simply "samples" and used to represent a larger area. However,  the long answer is that if a biopsy is done properly and from the right area, and read by a good pathologist, them no, it is very likely that if a biopsy returns showing that androgenetic alopecia is one of the diagnoses that this is correct. The identification of vellus hairs and a terminal to vellus hair ratio of less than 4:1 with telogen hairs less than 15% is typical of androgenetic alopecia. Many individuals (especially women) with androgenetic alopecia do not have a family history so this fact should not be given too much emphasis.


A biopsy can "sometimes" be wrong in these situations:

1. Diagnoses of Scarring Alopecia (Lichen planopilaris, Folliculitis Decalvans)

2. Some diagnoses of Telogen Effluvium

3. Some diagnoses of Alopecia Areata

Most of the time, of course, a biopsy is correct in these situations. However, there are many cases alopecia areata, telogen effluvium and scarring alopecia that are challenging. A biopsy is just a piece of the puzzle and one must put together all the facts from the clinical history. examination, blood test results to come up with the diagnosis. 


A biopsy is less likely to be 'wrong' in these situations

1. Androgenetic alopecia (especially with use of horizontal sections)

2. Tinea Capitis

3. Trichotillomania

4. Skin Cancers and Metastases



Dr. Jeff Donovan is a Canadian and US board certified dermatologist specializing exclusively in hair loss. To schedule a consultation, please call the Whistler office at 604.283.1887

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