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# Agents of chromoblastomycosis (Fonsecaea and other pigmented fungi)

- Fungus
- For completeness

Dark fungi of soil and wood that enter through a wound, usually on a farmer's leg, and form slow-growing wart-like plaques.

Updated 2026-11-01

Also called: Fonsecaea pedrosoi, Cladophialophora carrionii, Phialophora verrucosa, chromomycosis

## Key points

- Dark (dematiaceous) fungi that enter through trauma
- Wart-like plaque on a farmer's leg
- KOH: brown muriform bodies (sclerotic or Medlar bodies)
- Itraconazole or terbinafine, plus physical methods
- Risk of squamous cell carcinoma in old lesions

## At a glance

**Shape**
In tissue, muriform bodies: round thick-walled cells divided by septa in several planes

**Family**
Herpotrichiellaceae (Chaetothyriales)

**Type**
Dematiaceous molds (pigmented with melanin)

**Stain**
KOH: copper-brown muriform bodies, visible without special stains

**Size**
Muriform bodies of about 5–12 µm

## Morphology

- Muriform (sclerotic) bodies: brown, thick-walled cells divided crosswise
- In culture: dark colonies, olive green to black
- Melanin in the wall gives them their colour

## Transmission

- Traumatic skin inoculation with splinters, thorns or plant material
- More common in people who work barefoot or unprotected in the fields
- Not spread from person to person

**Reservoir:** Soil, wood and plant debris in tropical areas

### Isolation precautions

What the care team adds to standard precautions.

- Standard

## Virulence factors

- Melanin in the wall: resists killing by phagocytes
- Muriform bodies persist in tissue and keep up chronic granulomatous inflammation
- Slow growth with fibrosis

## Diseases it causes

- Chromoblastomycosis: a chronic implantation mycosis with wart-like plaques and nodules on the limbs [Sporotrichosis and other subcutaneous mycoses →](https://durgical.com/en/conditions/sporotrichosis-and-other-subcutaneous-mycoses/)

## Clinical picture

- Small painless first lesion on the leg or forearm
- Wart-like or cauliflower plaques that grow over years
- Black dots on the surface (good spots to sample)
- Complications: lymphedema, bacterial infection and squamous cell carcinoma in old lesions

## Diagnosis

- Scraping of the black dots with KOH: brown muriform bodies
- Biopsy: granulomas with muriform bodies
- Culture and molecular methods for the species

## Treatment

Long oral antifungal courses (itraconazole, terbinafine), often combined with physical methods (cryotherapy, heat) or surgery for small lesions. Large, old lesions respond poorly.

Drug class only; doses and regimens are set by the clinician from the current guideline.

In Pharmacology:

- [Itraconazole](https://durgical.com/en/pharmacology/itraconazole/)
- [Terbinafine](https://durgical.com/en/pharmacology/terbinafine/)

## Prevention

- Footwear, gloves and protective clothing in farm work
- Early care for a wart-like lesion that does not heal

## In Colombia

Colombia is among the countries of the Americas with the most recorded cases relative to its population; it mainly affects adult men in rural areas who work the land. WHO has listed it among the neglected tropical diseases since 2017.

## Memory aid

Copper coins in the wart: the muriform bodies look like little copper coins split crosswise inside a warty lesion.

## Test yourself

Think of the answer, then tap the question to see it.

## What is seen on KOH of a chromoblastomycosis lesion?

Muriform bodies: brown, thick-walled cells divided by septa in several planes.

## How does a farmer acquire chromoblastomycosis?

By skin inoculation with splinters, thorns or contaminated plant material.

## Which malignant complication can arise in old chromoblastomycosis lesions?

Squamous cell carcinoma.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/microbiology/agents-of-chromoblastomycosis/)

## Related

- [Sporothrix schenckii](https://durgical.com/en/microbiology/sporothrix-schenckii/)
- [Paracoccidioides brasiliensis](https://durgical.com/en/microbiology/paracoccidioides-brasiliensis/)

## Related conditions

- [Sporotrichosis and other subcutaneous mycoses](https://durgical.com/en/conditions/sporotrichosis-and-other-subcutaneous-mycoses/)

## What the colours mean

**Gram-positive**
Thick peptidoglycan wall: stains purple.

**Gram-negative**
Thin wall with an outer membrane: stains pink.

**Acid-fast**
Lipid-rich wall (mycobacteria): Ziehl–Neelsen stain.

[← Back to the group: Molds and dermatophytes](https://durgical.com/en/microbiology/groups/molds-and-dermatophytes/)

Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Chromoblastomycosis](https://www.who.int/news-room/fact-sheets/detail/chromoblastomycosis) (WHO, 2023); [The global burden of chromoblastomycosis](https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0009611) (PLOS Neglected Tropical Diseases, 2021).

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

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Source: https://durgical.com/en/microbiology/agents-of-chromoblastomycosis/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/microbiology/agents-of-chromoblastomycosis/