Chromoblastomycosis

Introduction

Chromoblastomycosis is a chronic fungal infection of the skin and subcutaneous tissue caused by pigmented (dematiaceous) fungi that are introduced into the skin through minor trauma, such as a thorn prick, wood splinter, or other penetrating injury.

The disease occurs predominantly in tropical and subtropical regions and mainly affects individuals involved in agriculture, forestry, and other outdoor occupations where skin injuries from vegetation are common.

The infection progresses slowly over months to years and, if left untreated, may result in extensive skin involvement, secondary bacterial infection, and permanent disability.

Predisposing factors include:

• Minor skin trauma (e.g., thorn prick, splinter)

• Agricultural and outdoor occupations

• Walking barefoot or working without protective clothing

• Tropical and subtropical climates

• Delayed diagnosis or inadequate treatment

• Immunosuppression (less common)

Pathophysiology:Pigmented fungi are inoculated into the skin following trauma. The organisms establish a chronic localized infection that induces granulomatous inflammation, leading to the gradual formation of nodules that enlarge into characteristic verrucous (wart-like) plaques.

Signs & Symptoms

• Small papule or nodule at the site of injury

• Slowly enlarging nodule that progressively develops into a verrucous plaque

• Warty, rough, cauliflower-like skin lesions

• Hyperkeratotic plaques with irregular borders

• Lesions may be skin-colored, reddish-brown, or darkly pigmented

• Mild itching or tenderness in some patients

• Crusting or ulceration in advanced disease

• Secondary bacterial infection may occur

Common sites:

• Lower limbs (most common)

• Feet

• Legs

• Hands

• Forearms

Course:

• Chronic and slowly progressive

• Usually remains localized but may enlarge over several years

• Untreated disease may cause significant tissue damage and disability

Diagnostic Criteria

• History of skin injury following contact with vegetation or soil

• Slowly progressive verrucous plaque or nodular lesion

• Chronic lesion that fails to respond to antibacterial therapy

• Demonstration of characteristic muriform (Medlar) bodies on microscopy or histopathology

• Identification of fungal elements on laboratory examination

Investigation

• Skin scraping or biopsy for direct microscopic examination

• Potassium hydroxide (KOH) preparation

• Skin biopsy for histopathology demonstrating muriform (sclerotic/Medlar) bodies

• Fungal culture for species identification where available

Consider differential diagnosis:

• Cutaneous tuberculosis

• Cutaneous leishmaniasis

• Sporotrichosis

• Verruca vulgaris (viral warts)

• Squamous cell carcinoma

• Mycetoma

Treatment

Non-Pharmacological Treatment

• Keep the affected area clean and dry.

• Avoid repeated trauma to the affected skin.

• Treat secondary bacterial infection if present.

• Encourage adherence to prolonged antifungal therapy.

• Surgical excision or other local destructive procedures may be considered for small, localized lesions where appropriate.

Pharmacological Treatment

• Itraconazole (PO) 200 mg once daily for 6–9 months.

Prevention

• Wear protective footwear while working outdoors.

• Use gloves and protective clothing when handling vegetation or soil.

• Clean and disinfect skin injuries promptly.

• Seek early medical attention for persistent nodules or warty skin lesions following trauma.

• Complete the full course of antifungal treatment to reduce recurrence.

Follow-up

• Review patients regularly to assess clinical response and treatment adherence.

• Monitor for adverse effects associated with prolonged itraconazole therapy.

• Continue treatment until complete clinical resolution.

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