[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Microbiology](https://durgical.com/en/microbiology/) › [Molds and dermatophytes](https://durgical.com/en/microbiology/groups/molds-and-dermatophytes/) › Agents of phaeohyphomycosis (Exophiala, Alternaria, Cladophialophora and other dematiaceous molds)

# Agents of phaeohyphomycosis (Exophiala, Alternaria, Cladophialophora and other dematiaceous molds)

- Fungus
- For completeness

Dark-pigmented molds from soil and plants. They cause skin cysts after splinters, sinus infections and, rarely, brain abscesses.

Updated Nov 13, 2026

Also called: dematiaceous fungi, black fungi, Exophiala, Alternaria, Cladophialophora bantiana, Bipolaris, Curvularia

## Quick facts

**Type**
Fungus · [Molds and dermatophytes](https://durgical.com/en/microbiology/groups/molds-and-dermatophytes/)

**Gram / shape**
In tissue

**Spread**
Traumatic implantation of soil

**Causes**
Subcutaneous phaeohyphomycosis

**Treatment**
Surgical excision of cysts and

On this page

- The basics Key points
- At a glance
- Morphology
- Transmission
- Memory aid
- What the colours mean

- Clinical Virulence factors
- Diseases it causes
- Clinical picture
- Diagnosis

- Treatment Treatment
- Prevention

- Study Test yourself

- Connections Connections

## Key points

- Phaeohyphomycosis = infection by melanin-pigmented molds with brown hyphae in tissue.
- Pigmented fungi give three pictures: muriform bodies (chromoblastomycosis), black grains (eumycetoma) or brown hyphae (phaeohyphomycosis).
- Fontana-Masson stains the melanin.
- Cladophialophora bantiana causes brain abscess even in immunocompetent people.
- Treatment: surgery plus a triazole.

## At a glance

**Shape**
In tissue: brown septate hyphae, yeast-like cells or short chains, never muriform bodies or sulfur granules

**Family**
Many; the black yeasts Exophiala and Cladophialophora belong to Herpotrichiellaceae (Chaetothyriales)

**Type**
Dematiaceous (melanin-pigmented) molds and black yeasts

**Stain**
Brown on H&E or unstained KOH; Fontana-Masson stain confirms melanin

## Morphology

- Brown to olive-black colonies on culture; the pigment is melanin in the cell wall.
- In tissue, pigmented septate hyphae and swollen yeast-like cells, sometimes faint and seen only with Fontana-Masson.
- The absence of muriform bodies separates it from chromoblastomycosis; the absence of grains separates it from eumycetoma.

## Transmission

- Traumatic implantation of soil or plant material (splinters, thorns) into the skin.
- Inhalation of spores into the sinuses or lungs.
- Spread through the blood to the brain in some species; not person to person.

**Reservoir:** Soil, wood, decaying plants and household water systems

### Isolation precautions

What the care team adds to standard precautions.

- Standard

## Virulence factors

- Melanin in the cell wall protects against oxidative killing by phagocytes and is the main shared virulence factor.
- Some species are thermotolerant and neurotropic (Cladophialophora bantiana, Exophiala dermatitidis).
- They can invade tissue in people with no obvious immune defect, but disease is more severe in transplant recipients.

## Diseases it causes

- Subcutaneous phaeohyphomycosis: a painless cyst or nodule on a limb, often after a splinter. [Sporotrichosis and other subcutaneous mycoses →](https://durgical.com/en/conditions/sporotrichosis-and-other-subcutaneous-mycoses/)
- Fungal sinusitis by Bipolaris, Curvularia or Alternaria: allergic or, in immunosuppressed hosts, invasive. [Fungal sinusitis (invasive and noninvasive) →](https://durgical.com/en/conditions/fungal-sinusitis/)
- Cerebral phaeohyphomycosis: brain abscess, classically by Cladophialophora bantiana, even in immunocompetent people. [Brain abscess →](https://durgical.com/en/conditions/brain-abscess/)

## Clinical picture

- The subcutaneous cyst grows slowly over months and is often mistaken for a ganglion or epidermal cyst.
- Transplant recipients may present long after transplantation with nodules, pneumonia or dissemination.
- Brain abscess presents with headache, focal deficit and seizures; mortality is high.

## Diagnosis

- Biopsy or aspirate: brown septate hyphae; Fontana-Masson stain is relatively specific for melanin in tissue.
- Culture on Sabouraud agar grows dark colonies; species are identified by morphology and ribosomal DNA sequencing.
- No routine antigen or serologic test exists; galactomannan and beta-D-glucan are unreliable here.

## Treatment

Surgical excision of cysts and, when possible, of brain abscesses is the key step. Triazoles (voriconazole, posaconazole, itraconazole) are the most active drugs; lipid amphotericin B is used in severe disease. There are no interpretive breakpoints, and outcomes in brain infection are poor.

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

In Pharmacology:

- [Voriconazole](https://durgical.com/en/pharmacology/voriconazole/)
- [Posaconazole](https://durgical.com/en/pharmacology/posaconazole/)
- [Itraconazole](https://durgical.com/en/pharmacology/itraconazole/)
- [Amphotericin B](https://durgical.com/en/pharmacology/amphotericin-b/)

## Prevention

- Gloves and closed footwear when working with wood, soil or plants.
- Prompt removal and cleaning of splinters.
- Watching for slow nodules in transplant recipients.

## Memory aid

«Brown threads, brown trouble»: when tissue shows brown threads instead of copper coins or grains, think phaeo, cut it out and add an azole.

## Test yourself

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

## What feature defines the agents of phaeohyphomycosis?

Melanin in the cell wall: they appear as brown septate hyphae or yeast-like cells in tissue.

## Which stain highlights melanin when the pigment is faint?

Fontana-Masson.

## How does phaeohyphomycosis differ from chromoblastomycosis in tissue?

Phaeohyphomycosis shows brown hyphae; chromoblastomycosis shows muriform (sclerotic) bodies.

## Which dematiaceous mold is classically linked to brain abscess?

Cladophialophora bantiana, which can infect people without obvious immunosuppression.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/microbiology/agents-of-phaeohyphomycosis/)

## 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.

## Connections

## Related 5

- [Agents of chromoblastomycosis (Fonsecaea and other pigmented fungi)](https://durgical.com/en/microbiology/agents-of-chromoblastomycosis/)
- [Mycetoma agents](https://durgical.com/en/microbiology/mycetoma-agents/)
- [Aspergillus fumigatus](https://durgical.com/en/microbiology/aspergillus-fumigatus/)
- [Fusarium and Scedosporium](https://durgical.com/en/microbiology/fusarium-and-scedosporium/)
- [Agents of superficial mycoses (Hortaea werneckii, Piedraia hortae, Trichosporon)](https://durgical.com/en/microbiology/agents-of-superficial-mycoses/)

## Related conditions 3

- [Sporotrichosis and other subcutaneous mycoses](https://durgical.com/en/conditions/sporotrichosis-and-other-subcutaneous-mycoses/)
- [Fungal sinusitis (invasive and noninvasive)](https://durgical.com/en/conditions/fungal-sinusitis/)
- [Brain abscess](https://durgical.com/en/conditions/brain-abscess/)

[← 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: [Phaeohyphomycosis in Transplant Patients](https://pmc.ncbi.nlm.nih.gov/articles/PMC5753083/) (Journal of Fungi (PMC), 2015); [U.S. Case Report of Cerebral Phaeohyphomycosis Caused by Ramichloridium obovoideum (R. mackenziei): Criteria for Identification, Therapy, and Review of Other Known Dematiaceous Neurotropic Taxa](https://pmc.ncbi.nlm.nih.gov/articles/PMC104613/) (Journal of Clinical Microbiology (PMC), 1998).

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Representative model, for educational purposes only.

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