This week I had a 35 year old man present with a one month history of a round patch of alopecia. He was told by his PMD that he had tinea and was started on oral terbinafine (which he had been on for 5 days when he first came to me). I saw the perfectly round patch of alopecia with exclamation mark hairs and of course diagnosed alopecia areata. I also noted some very short dark hairs, however, and took out my dermatoscope and saw “black dots”. Could this be tinea capitis mimicking alopecia areata? I took a culture, told him that while I felt it was probably alopecia areata, he should continue the medication until the culture results are available. Presumably, the results would be negative, and I would then treat him for AA in the standard manner.
I did some homework today and came across the following article
of the hair root remains adherent to the hair-follicle
ostium, giving the macroscopic appearance of a macrocomedo. We believe that a number of factors may induce formation of black dots, including perifollicular lymphocyte infiltration in the course of an autoimmunologically mediated inflammatory process in AA, a mixed
neutrophil-lymphocyte inflammatory infiltration in
DCS, cytotoxic and antiproliferating effects of chemotherapeutic
agents, and nonspecific factors such as mechanical injury in healthy people.”
does not allow differentiation of black dots from dystrophic
hair or broken hair in patients with trichotillomania or mycotic infection.”
I have always equated alopecia with black dots as being Trichophyton tonsurans until proven otherwise. Unfortunately, I learned that rule well before dermoscopy and trichoscopy became in vogue.