Trichomycosis axillaris

Presentation

It is characterized by the presence of concretions along the hair shafts, clinically observed as yellow, and rarely as red or black nodules. These concretions derive from bacterial colonization along the hair shaft containing dried apocrine sweat with a cementing substance generated by the bacteria.

Cause

It is caused by several species of Corynebacterium.

Obesity, hyperhidrosis, poor local hygiene, and warm, moist environments are common predisposing factors.

Diagnosis

The infection is diagnosed by close examination of the hair shafts where brown to yellow material called concretions are seen. There is usually an associated rancid odour. A microscopic examination can confirm the diagnosis, but this is rarely needed.

Some patients with excessive sweating present the so-called corynebacterial triad, that is, the simultaneous presence of trichomycosis axillaris, erythrasma, and pitted keratolysis.

Treatment

No specific therapeutic studies on trichomycosis are available.

Many authors consider that the most effective treatment consist in shaving of the affected area for a period of 2–3 weeks. The use of a concomitant treatment, such as sulfur soaps or benzoyl peroxide is also recommended. Rubbing whilst washing may help to disrupt the biofilm, hence increasing the accessibility of antiseptics to the bacteria.

Patients who shave the affected area only once will generally experience a recurrence of the infection, since, the bacteria begin to develop the concretions once again as the hair grows back.

Corynebacterium infections are related to excessive sweating; for this reason, deodorants containing an aluminum chloride solution may be used for treatment and prevention.

Maintaining good local hygiene is recommended.

References

References

1. (2007). "Dermatology: 2-Volume Set". Mosby.
2. (January 2013). "Trichomycosis (trichobacteriosis): clinical and microbiological experience with 56 cases". International Journal of Trichology.
3. (October 2013). "Images in clinical medicine. Trichomycosis axillaris". The New England Journal of Medicine.
4. (2013). "Answer: Can you identify this condition?". Canadian Family Physician.
5. (February 2008). "A corynebacterial triad: Prevalence of erythrasma and trichomycosis axillaris in soldiers with pitted keratolysis". Journal of the American Academy of Dermatology.
6. (September 2008). "Corynebacterium-associated skin infections". International Journal of Dermatology.
7. (September 2015). "Creamy Yellow Concretions in Axillary Hair". JAMA Dermatology.
8. Swart MN, Weinberg AN. Bacterial diseases with cutaneous involvement. In: Fitzpatrick’s Dermatology in General Medicine, 6th edn. New York: McGraw-Hill, 2003: 1843–1878.