A Readily Missed Diagnosis

Penicillium marneffei is a dimorphic fungus that causes one of the most common opportunistic infections in Asian patients with AIDS. The diagnosis is established by microbiologic culture, requiring at least several days. A presumptive diagnosis can be made by cytologic or histologic examination of biopsied or aspirated tissue. Bone marrow biopsy is often performed in the workup of patients with AIDS who have fever or hematologic abnormalities and can provide prompt diagnosis of opportunistic infection. We report the bone marrow findings in the largest series of patients with culture-proven P marneffei infection. In the bone marrow, the histiocytes can occur in large numbers and be easily recognized or may be extremely subtle. P marneffei infection is sometimes no