Page 52 - Haematologica Atlas of Hematologic Cytology

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Figure 10. Histoplasma capsulatum in peripheral blood. Among fungal diseases, yeasts more than molds may be oc- casionally found in bone marrow aspirates. In these cases the bone marrow study had been performed in order to se- arch for hematological abnormali es or Leishmania infec on. Even rarer is involvement of peripheral blood, observed in massive disseminated disease. The above picture refers to the peripheral blood of a young woman, hospitalized because of advanced HI infec on. She was born in Colombia and recently had moved to Italy. Epidemiological issues suggested searching for Leishmania. The microscopic examina on of bone marrow smears showed oval-shaped orga- nisms inside a number of cells, namely granulocytes as well as outside the cells. They measured 3-4 m x 2-3 m in size and, though resembling Donovan’s bodies, i.e. Leishmania organisms, they lacked the kinetoplast. The intracellu- lar burden of organisms ranged from 1 through 20. A cue to the diagnosis of histoplasmosis was the pa ent s origin. Actually the area of South America where the pa ent had lived is inside the “Histoplasmosis Belt”, that is the area between 35° N and 35° S. Histoplasma capsulatum organisms are oval-shaped and a clear space surrounding each organism may be recognized even a er Giemsa staining. The space corresponds to the capsular component of the organism. More properly it is a peudocapsule due to the shrinkage of the cytoplasm of the infected cell. Although sha- ring the oval shape, Histoplasma organisms show a far greater variability in size compared to Leishmania organisms. et, lack of the kinetoplast and presence of the capsule are the two most important characters dis nguishing the two organisms. Infected white blood cells usually show a distorted nucleus and cytoplasm shrinkage. The diagnosis of Hi- stoplasmosis was con rmed by a strongly posi ve serology as well as by culture providing a huge load of the fungus.
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