Histoplasmosis of bone.

A case of histoplasmosis of bone manifested by a single punched-out lesion in the humerus is reported in a man with asymptomatic mild chronic disseminated histoplasmosis. Roentgenologically evident lesions of bone due to Histoplasma capsulatum are rare, and this is the only report of a large punched-out lytic lesion. Such lesions are common in disseminated histoplasmosis due to the African strain H. duboisii. Although H. duboisii has been accorded species differentiation, there are only two clearly defined differences, compared to H. capsulatum. One is morphologic (size of yeast cell), and the other is a different clinical disease spectrum. Many believe that this organism is best viewed as a stable variant of H. capsulatum. At times, the two strains are indistinguishable morphologically, and at times, as in the case reported, there may be clinical similarities in their respective disease entities.