Case 170. Chromomycosis (65 y-o F)
    Biopsy from a painlless infiltrative and scaling nodule on the dorsum of the hand    
Key words : 
Fonsecaea pedrosoi, chromomycosis, sclerotic cell, pheohyphomycosis, Exophiala jeanselmei    
Infiltrative verrucous lesions, formed on the dorsum of the hand, are painless.   Suppurative granuloma is formed against Fonsecaea pedrosoi. Brown-colored rouded fungi are found in the lesion (HE).
A brown-colored sclerotic cell (muriform cell) is phagocytized by a multinucleated giant cell in the inflamed dermis (HE, high power).   A chain of pigmented sclerotic cells are surrounded by neutrophils in this view (HE). Mycelia are never formed in the tissue.
Reference case 170A
Cut surfaces of large black nodules formed near the A-V shunt for hemodialysis in a 13 y-o boy (gross findings). The dermis contains multiple black nodules with necrotic foci.
  Reference case 170A
Numerous sclerotic cells are seen in and outside phagocytic macrophages (HE). Proliferation of the pigmented fungi is accelerated by the immunosuppression due to chronic renal failure and hemodialysis.
Reference case 170B
Pheohyphomycosis (infection of hyphae-forming pigmented fungi) in the dermis in a patient of acute leukemia. Growth of hyphae-forming pigmented fungi is seen in the abscess cavity. Infection of hyphae-forming Exophiala jeanselmei is promoted by an immunosupressed state. Secondary brain abscess may occur.
  Reference case 170C
Pheohyphomycosis (pheo = brown). An encapsulated paraarticular 5 mm nodule seen in the middle finger (67 y-o M). Subcutaneous cyst formation is the most common presentation of pheohyphomycosis. The lesion is composed of geographical mixture of abscess and epithelioid granuloma (HE, low power).
Reference case 170C
High powered view of the circumscribed cystic lesion (HE). Pigmented hyphae are phagocytized by macrophages located adjacent to neutrophilic exudation.
  Reference case 170C
Grocott's silver identifies hypha-forming fungi in the granulomatous lesion. The lesion seen in the immunopatent patient can be caused by traumatic implantation of wood splinter.