Case report 699. Primary localized skeletal cryptococcosis (torulosis) of the right tibia at its proximal end.

The case of a 58-year-old man with a normal immune status with primary localized skeletal cryptococcosis of the right tibia was presented. Radiologically it appeared as an osteolytic lesion with marginally indistinct borders in the epimetaphyseal region of the proximal tibia. Histologically, necrotizing granulomatous inflammation was associated with a prominent fibrohistiocytic reaction. The presence of cryptococci was confirmed by special stains. Clinicopathological features and the therapeutic aspects of this rare infective bone lesion were discussed. It is uncommon today, particularly in developed countries, to encounter a localized skeletal fungal infection. Therefore, radiologists and pathologists generally may be unfamiliar with the appearance of the lesion and tend not to consider the possibility of fungal osseous disease in the differential diagnosis. Unless it is remembered that fungal infection may cause a localized bone lesion with varied histological responses, the diagnosis may be overlooked, and bacteriologic proof may not be sought.