Histoplasmosis pathology

Histoplasmosis is caused by Histoplasma capsulatum, a dimorphic fungus. It is distributed worldwide and predominant in certain regions of North and Central America. Cutaneous Manifestations are reported to occur in 10% to 25% of AIDS patients with disseminated histoplasmosis

Histology histoplasmosis

Histopathological examination of histoplasmosis reveals a dense dermal infiltrate low attenuated or uncomplicated epidermis (Figure 1). In the higher power, the infiltrator is revealed to contain numerous plasma cells, histiocytes and lymphocytes (Figure 2). Depending on the state of the host and the stage of the injuries can be extensive granulomas. Accompanying the infiltrate are numerous budding yeast forms, predominantly within histiocytes, and few organisms residing extracellularly A clear space or artificial "halo" may be evident due to retraction of the basophilic fungal cell cytoplasm of the poorly stained cell wall (Figure 2, arrow). GMS confirms the presence of numerous fungal spores of 2–4 μm compatible with Histoplasma capsulatum (Figure 3).

Special spots for histoplasmosis.

In histoplasmosis, GMS and PAS are often required to help illustrate characteristic yeasts. This is especially useful in immunocompetent Hosts with a quick inflammatory reply.

Differential diagnosis histoplasmosis pathology

Cryptococcus and blastomycosis: Mucicarmine positivity discriminates crytococcus from these other organisms. Blastomycosis is much bigger organism and lacks the typical halo seen around forms of histoplasmosis. Blastomycosis generally causes rapid epidermal reply.