July/August 2001

4.

5.

Diagnosis: Disseminated Cryptococcus in an apparently immunocompetent patient

Histopathology: Under low power, the biopsy specimens showed a papular inflammatory infiltrate composed of a mix of lymphocytes, macrophages, and multinucleated giant cells(Fig 4). High power examination revealed encapsulated yeast forms which stained positively with a GMS stain. Culture of the biopsied tissue grew abundant Cryptococcus neoformans (Fig 5).

Discussion:

Cryptococcus neoformans is an encapsulated yeast which most frequently infects immunocompromised patients. There are two subtypes which infect, C. neoformans neofonnans (serotypes A and D), which is found in the droppings of bats and pigeons and usually infects immunocompromised patients, and C. neoformans gatti (serotypes B and C), which is found in the debris of eucalyptus trees and more commonly infects immunocompetent patients. Transmission is usually caused by inhalation of the organism.

The most common form of infection in immunocompetent hosts is isolated pulmonary infection, which usually resolves spontaneously without treatment. In patients who are immunocompromised due to HIV, lymphoma, sarcoidosis, diabetes, collagen vascular disease, or organ transplantation, cryptococcal infection may spread from the lungs to other organ systems. The most common manifestation of cryptococcal infection in immunocompromised patients is meningitis, but disseminated disease also occurs.

Approximately 10-15% of immunocompromised patients with disseminated Cryptococcus have cutaneous findings. Skin manifestations of cryptococcal infection are variable, ranging from papules and indurated plaques, sometimes with ulceration, to diffuse cellulites resembling a bacterial cellulitis.

Treatment of cryptococcal. infection in immunocompromised patients consists of 10-14 days of IV amphotericin B plus flucytosine, followed by long-term (2-6 mo.) oral fluconazole. In immunocompentent patients with symptomatic infections not requiring hospitalization, oral fluconazole alone has been reported to be successful. Mildly symptomatic immunocompetent patients with isolated pulmonary cryptococcosis do not usually require treatment.

The patient in the current case worked as a roofer, and did report significant occupational exposure to pigeon droppings. Even with significant exposure to the organism, it is unusual for an immunocompetent patient to develop disseminated disease. He will require long-term follow up to discover whether he has an occult disease causing immunosuppression.

References:

1. Nfliftez M, Peacock JE, Chin R. Pulmonary cryptococcosis in the immunocompetent host. Chest 2000; 118:527-534.

2. Sheu S, Chen Y, Kuo N, Wang J, Chen C. Endogenous cryptococcal endophthalmitis. Ophthalmology 1998;377-381.

3. Peachey PR, Gubbins PO, Martin RE. The association between cryptococcal variety and immunocompetent and immunocompromised hosts. Pharmacotherapy 1998; 18:257-264.

4. Hay RJ. Deep fungal infections. In: Dermatology in General Medicine, 5 th ed, Vol. Dermatology In Genderal Medicine Freedberg IM, Eisen AZ, et al, eds. Pages 23832384.

My thanks to Dr. Dan Wendelin for his assistance in the preparation of this case.