Cryptococcosis, also called Busse-Buschke's disease, torulosis, and European blastomycosis, is an infection that has its most severe
effects on the central nervous system. Skin cryptococcosis occurs in approximately 15% of patients with disseminated disease. The disease is caused by Cryptococcus neoformans,
the only basidiomycete known to cause deep fungal infections. Cryptococcosis is reported most frequently from temperate regions. C. neoformans is ecologically associated with birds, especially pigeons, because it thrives in their excreta. The organism passes harmlessly through the
bird's gut. Pigeon fanciers often have antibodies, indicating frequent exposure, but do not have an
increased rate of infection. C. neoformans is easily recovered from pigeon excrement but is rapidly cleared from soil by Acanthamoeba organisms. In Australia, Cryptococcus neoformans var gattii is closely associated with Eucalyptus camaldulensis, one
of the few trees on which koalas feed. Koalas pass the yeast fecally (in the same ecological role served by pigeons elsewhere) but also contract cryptococcosis occasionally. Serious infections caused by Cryptococcus neoformans var gattii have been found not only in immunocompromised but also in patients with normal immune system. Persons at increased risk for infection are those with impaired cell-mediated immunity from, for example, chronic corticosteroid therapy, lupus erythematosus, sarcoidosis, or iatrogenic immunosuppression
associated with organ transplantation. Cryptococcal infection in an HIV-infected
person meets the CDC definition for AIDS. Indeed, the unexpected diagnosis of cutaneous cryptococcosis requires prompt evaluation for other involved organs and for underlying immunodeficiency.
SIGNS
The primary infection in cryptococcosis is pulmonary,
but involvement of the central nervous system is the most common and serious complication.
Cutaneous manifestations appear in approximately 15% of persons with disseminated disease,
occasionally before the start of life-threatening meningeal involvement. The clinical diagnosis of cutaneous cryptococcosis is difficult because the manifestations are diverse and nonspecific. Most often, painless papules arise on the head or neck and then evolve
into nodules, pustules, abscesses, grouped vesicles, purpura, vasculitis, plaques, or ulcers. Two uncommon but well-described cutaneous presentations are cryptococcal cellulitis in prednisonetreated patients who have had renal transplants and molluscum-like facial papules in patients with AIDS. More rarely, the lesions resemble pyoderma gangrenosum or Kaposi’s sarcoma. Primary inoculation cryptococcosis is extremely rare and it is best
to consider a cutaneous lesion evidence of disseminated cryptococcosis until proven otherwise.
TREATMENT
Disseminated cryptococcosis is usually fatal if
untreated. Combination therapy with flucytosine and amphotericin is the treatment of choice for cryptococcal meningitis. Fluconazole is proving increasingly valuable in managing cryptococcosis in patients with AIDS.