Author: Assoc Prof Patrick Emanuel, Dermatopathologist, Auckland, New Zealand, 2013.
Chromoblastomycosis (chromomycosis) is caused by quite a variety of pigmented fungal species common in soil and plant matter.
Histology of chromoblastomycosis
Chromoblastomycosis organisms often elicit a profound epidermal hyperplastic reaction which may mimic a squamous cell carcinoma (figures 1, 2). There are often intraepidermal neutrophilic abscesses and transepidermal elimination of inflammatory debris. There is a suppurative and granulomatous response in the dermis (figure 3-6). Eosinophils may be numerous. Later stages often show an impressive dermal fibroplasia.
Within the infiltrate, the organisms can be seen on haematoxylin-eosin sections (figures 3-6, arrows). The organisms are brown, round and have a thick wall. They are thought to represent an intermediate form between hyphae and yeast. The round bodies are sometimes seen fused together as “septate bodies” (figure 4, arrows).