Wednesday, August 13, 2025

Chromoblastomycosis

Chromoblastomycosis: Causes, Symptoms, Diagnosis, and Management

~Introduction

Chromoblastomycosis, also known as chromomycosis, is a chronic fungal infection of the skin and subcutaneous tissue caused by pigmented (dematiaceous) fungi. It is considered a neglected tropical disease by the World Health Organization (WHO) and is commonly seen in rural agricultural areas of tropical and subtropical regions. The infection develops slowly, often over months or years, and can cause significant disability if untreated.

This disease is notable for its wart-like lesions, prolonged course, and difficulty in complete eradication, making early detection and treatment crucial.

~Epidemiology

Geographic distribution: Found predominantly in Central and South America, Africa, Asia, and some parts of the Pacific.
Climate preference: Warm, humid tropical and subtropical climates.
Occupational risk: Agricultural workers, gardeners, and people frequently in contact with soil, decaying vegetation, and plant matter are at higher risk.
Gender and age: More common in adult men due to greater occupational exposure.

~Causative Agents

Chromoblastomycosis is caused by dematiaceous (darkly pigmented) fungi that produce melanin in their cell walls, giving them a dark brown or black color in tissue.
Common species include:

Fonsecaea pedrosoi – most common worldwide.
Cladophialophora carrionii – seen in arid climates.
Phialophora verrucosa
Fonsecaea compacta
Rhinocladiella aquaspersa

These fungi are saprophytes in soil and plant debris but can become opportunistic pathogens when introduced into human skin through trauma.

~Mode of Transmission

Entry route: Traumatic implantation of fungal spores into the skin through cuts, splinters, thorns, or insect bites.
Person-to-person transmission: Extremely rare; the infection is not contagious.
Incubation period: Can range from several weeks to months before symptoms appear.

~Pathogenesis

Initial entry: Minor skin injury introduces fungal elements into subcutaneous tissue.
Immune response: The host mounts a chronic inflammatory reaction, leading to granuloma formation.
Slow progression: Over months or years, lesions enlarge and spread locally, rarely invading deeper structures.
Characteristic cells: The hallmark of infection is the presence of sclerotic bodies (Medlar bodies) — thick-walled, brown, round fungal cells seen under the microscope.

~Clinical Features

Chromoblastomycosis progresses slowly and can present in various forms:

Stages and Lesion Types

Nodular stage – small, firm papules or nodules at the trauma site.
Plaque stage – scaly, reddish-brown plaques.
Verrucous stage – large, wart-like lesions with irregular surfaces.
Tumorous stage – cauliflower-like growths.
Cicatricial stage – scar-like lesions after partial healing.

Common Symptoms

Painless, slowly enlarging skin lesions.
Itching or mild tenderness.
Lesions typically on lower limbs (feet, legs), but hands, arms, and face can be involved.
Secondary bacterial infections may occur.

Complications

Lymphedema and elephantiasis-like swelling due to lymphatic obstruction.
Secondary infections with bacteria or other fungi.
Rarely, squamous cell carcinoma in long-standing lesions.

~Diagnosis

Diagnosis is made through clinical examination and confirmed with laboratory investigations.

1. Direct Microscopy

Skin scrapings or tissue are examined with 10% potassium hydroxide (KOH).
Presence of sclerotic (Medlar) bodies — thick-walled, brown, round fungal cells — is diagnostic.

2. Culture

Specimens cultured on Sabouraud dextrose agar.
Growth may take 2–4 weeks.
Colony color: dark brown to black.

3. Histopathology

Granulomatous inflammation with sclerotic bodies in dermis.
Special stains: Periodic acid–Schiff (PAS) and Gomori methenamine silver (GMS).

4. Molecular methods

PCR and DNA sequencing for species identification (useful in research or severe cases).

~Differential Diagnosis

Conditions that may mimic chromoblastomycosis include:

Cutaneous tuberculosis
Verrucous carcinoma
Sporotrichosis
Leprosy
Mycetoma

~Treatment

Treatment is challenging and often requires a combined approach.

1. Antifungal Therapy

Itraconazole (200–400 mg/day for several months to a year) – most commonly used.
Terbinafine – effective alternative.
Posaconazole or voriconazole – for resistant cases.
Treatment duration: often 6–12 months or longer.

2. Physical and Surgical Methods

Cryotherapy – liquid nitrogen applied repeatedly to destroy lesions.
Thermotherapy – localized heat application.
Surgical excision – effective for small, well-defined lesions.

3. Combination Therapy

Antifungals + cryotherapy often yield better results.
Early, localized disease responds better than advanced cases.

~Prevention

Since the infection is environmental, prevention focuses on protective measures:

Wearing protective clothing, gloves, and footwear while working outdoors.
Immediate cleaning and disinfection of skin wounds.
Public health education in endemic regions.

~Prognosis

Early cases: Good prognosis with complete cure possible.
Advanced cases: Chronic, relapsing course; significant disfigurement possible.
Lesions rarely cause death but can cause long-term disability and stigma.

~Global Health Perspective

Chromoblastomycosis is a neglected tropical disease with limited public awareness and resources for control. Improving early diagnosis, training healthcare workers, and providing affordable antifungal treatment are essential to reduce the disease burden.

~Conclusion

Chromoblastomycosis is a slowly progressive fungal skin infection caused by pigmented fungi from the environment, primarily affecting people in rural, tropical areas. While not fatal, it can cause chronic disability if untreated. Early recognition and a multimodal treatment approach significantly improve outcomes. Education, protective measures, and accessible healthcare remain key to preventing and controlling this neglected disease.

Health Lines

Wednesday, August 13, 2025