Coccidioidomycosis is endemic to southwestern USA and California. The organism grows easily on agar at room temperature. As such cultures are highly infectious; deep fungal infections should never be cultured in the office setting.

While most other deep fungal organisms have a characteristic size and shape, Cryptococcus varies markedly in size and shape. The organisms are “gregarious” and cluster within clear spaces that correspond to the mucinous capsule. The capsule stains red with mucicarmine. Although they never appear brown in tissue, the organisms stain with a Fontana–Masson melanin stain. Umbilicated, molluscum-like lesions are often associated with human immunodeficiency virus (HIV).

Despite the name, Histoplasma capsulatum lacks a true capsule. The organisms are similar in size and shape to Leishmania, but lack a kinetoplast. The distribution of the organisms within the histiocyte is helpful. Histoplasma organisms are evenly spaced and surrounded by a pseudocapsule. In contrast, Leishmania