Case Nine – September 2017

  • Patient Information
    • 75 year old female presented with a 3 cm keratotic nodule on her inferior forearm
  • Clinical Diagnosis
    • Squamous Cell Carcinoma
  • Histology

    Sections show an endophytic squamous proliferation with associated suppurative and granulomatous inflammation.

    Brown, pigmented sclerotic bodies are present within multinucleated giant cells.

  • Final Diagnosis

    Chromoblastomycosis

    • Chromoblastomycosis is a chronic cutaneous fungal infection caused by traumatic inoculation, commonly through splinters, of dematiaceous fungi
    • Dematiaceous fungi are common in soil, wood and plant material
    • The most common organisms include: Phialophora verrucosa, Fonsecaea pedrosi, Fonsecaea compacta, Cladosporium carrionii, and Rhinocladiella aquaspersa
    • Dematiaceous fungi are characterized by the presence of melanin within their walls
    • Patients present with slow growing verrucous lesions, most commonly on the lower extremity or hand
    • Histology shows reactive pseudoepithelimatous hyperplasia that mimics squamous cell carcinoma with associated suppurative and granulomatous inflammatory infiltrate containing dematiaceous fungal structures called sclerotic cells or Medlar bodies
    • Sclerotic or Medlar bodies are brown, circular to oval fungal structures with thick walls ranging in size from 4-12 µm
    • Special stain for melanin (Fontana-Masson) is positive within the walls of the fungus
    • Small lesions can be treated with surgical excision, while larger lesions require oral antifungal therapy
  • Summary
    • Chromoblastomycosis is a chronic cutaneous fungal infection caused by traumatic inoculation, commonly through splinters, of dematiaceous fungi
    • Dematiaceous fungi are characterized by the presence of melanin within their walls and are positive for Fontana-Masson special stain
    • Patients present with verrucous lesions most commonly on the lower extremity or hand
    • Histology shows reactive pseudoepitheliomatous hyperplasia that mimics squamous cell carcinoma with associated suppurative and granulomatous inflammatory infiltrate containing sclerotic cells or Medlar bodies, which are circular, brown fungal structures ranging in size from 4-12 µm in diameter
    • Small lesions can be treated with surgical excision, while larger lesions require oral antifungal therapy