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Several weeks ago, I noticed a small spot on my forearm, about the size of a large freckle. It was innocuous, entirely ordinary. I assumed it was a bruise or other minor skin irritation. After six or seven weeks, it had not changed or disappeared, so I decided to have a dermatologist examine it.
The dermatologist did not think it appeared particularly concerning. Nevertheless, she suggested a biopsy “just to be safe.” About a week later, she telephoned me with an unexpected question:
“Have you recently traveled to Africa or South America?”
The biopsy showed a condition called chromomycosis (sometimes grouped under the broader category of chromoblastomycosis), a fungal skin infection caused by pigmented environmental fungi. These fungi are associated with soil, decaying vegetation, wood debris, mulch, compost, and similar organic material. They can occasionally enter the skin through tiny cuts, scratches, punctures, splinters, or thorn injuries and often so minor they go unnoticed.
compost piles,
mulch,
decomposing leaves,
woody debris,
potting soils, and
fungal-rich organic matter.
We can’t know the precise source of my exposure, but environmental contact through gardening and compost handling appears most plausible. Fortunately, these infections are usually localized, and when identified early, can be treated with a simple outpatient excision. Left untreated, they may slowly enlarge and become more difficult to eradicate, requiring more burdensome treatment.
My experience serves as a gentle reminder to others to be mindful of small lesions and spots. There should be no cause for alarm. Cases such as mine are uncommon. Nonetheless, awareness is valuable.
Of course, some sensible precautions for gardeners may include:
Gloves can protect skin from disease.
Image generated by MG Len Friedman using ChatGPT.
wearing gloves when handling compost or thorny material,
cleaning scratches and punctures promptly,
protecting forearms when working in dense vegetation, and
paying attention to skin lesions that persist for weeks without healing.
As Master Gardeners, we know humans are participants in the ecological web. Perhaps we don’t want to get quite so close to some organisms!
Additional Scientific Notes
Chromomycosis/chromoblastomycosis is most often caused by darkly pigmented (“dematiaceous”) fungi such as species within the genera Fonsecaea, Cladophialophora, and Phialophora. These organisms are more commonly reported in tropical and subtropical climates, but environmental exposure can occur elsewhere, including North America. The infection is usually acquired by traumatic implantation into the skin rather than by inhalation or person-to-person transmission.
Common features include:
slow growth,
persistence,
nodules or plaques,
pigmentation, and
in some cases, crusting or wart-like lesions.
Diagnosis is generally made by biopsy and special fungal stains.
Suggested References
Centers for Disease Control and Prevention (CDC) — Fungal Diseases (https://www.cdc.gov/fungal/).
DermNet NZ — Chromoblastomycosis (https://dermnetnz.org/topics/chromoblastomycosis).
Merck Manual Consumer Version — Fungal Skin Infections (https://www.merckmanuals.com/home/skin-disorders/fungal-skin-infections).
American Academy of Dermatology (https://www.aad.org/).
