Background
Trichomycosis axillaris is a relatively common superficial corynebacterial colonization of the axillary hair shafts characterized by the presence of adherent granular concretions and a benign clinical course. When the pubic hair is affected, the condition is referred to as trichomycosis pubis. [1] Shelley and Shelley noted the coexistence of erythrasma, trichomycosis axillaris, and pitted keratolysis and termed it the corynebacterial triad. [2]
Pathophysiology
Corynebacteria are gram-positive rods and a major component of the cutaneous flora. A warm and moist local environment contributes to bacterial overgrowth. Hyperhidrosis and poor hygiene are risk factors for disease.
Etiology
In 1952, Crissey et al identified Corynebacterium tenuis as the causative bacterium of trichomycosis axillaris [3] ; however, more recent reports suggest that the condition is caused by several species of the gram-positive diphtheroid Corynebacterium. [4, 5] It is not caused by a fungus, as the name may imply.
Epidemiology
Frequency
United States
No studies have assessed the frequency of trichomycosis axillaris in the United States.
International
In one study from the United Kingdom, trichomycosis axillaris was present in 27% of adult male students, and in the general population, 42% of male patients and 7% of female patients. Rho and Kim reported the corynebacterial triad in 13% of 842 Korean soldiers. [6]
Race
No racial predilection is reported for trichomycosis axillaris.
Sex
Both sexes may be affected; however, trichomycosis axillaris appears to affect males more commonly, since most women shave their axillary hair.
Age
Trichomycosis axillaris can affect any age group from puberty through adulthood.
Prognosis
Trichomycosis axillaris is a benign infection of the hair with no associated mortality or complications. Once treated, it may recur if preventive measures (eg, shaving, antibacterial soap, antiperspirants) are not taken.
Patient Education
Instruct patients with trichomycosis axillaris to keep the area dry and clean. Shaving or trimming axillary hair usually is beneficial.
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Yellow concretions are seen over axillary hairs.
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Close-up view of axillary hairs.
