Clinical Significance and Histologic Characterization of Histoplasma Granulomas

To clarify the clinical significance and degree of resolution (ie, grade) of Histoplasma granulomas in routinely reviewed surgical pathology specimens and the clinical outcomes of patients with this diagnosis, with an emphasis on those not receiving antifungal therapy.

We performed a retrospective medical record, laboratory data, and surgical pathology slide review of patients with Histoplasma granulomas following institutional review board approval.

Clinical, pathologic, and laboratory data from 62 patients with Histoplasma granulomas were available for review. Of these, 1 of 19 (5%) fungal cultures, 4 of 12 (33%) fungal serologic studies, 0 of 9 Histoplasma urinary antigen tests, and 0 of 2 Histoplasma serum antigen tests were positive. All but 3 of the Histoplasma granulomas were either in the resolving (grade 2) or resolved (grade 3) stage of resolution. None of the patients, including those who did not receive antifungal therapy after the histologic diagnosis, developed progressive or disseminated histoplasmosis.

These findings, which are supportive of clinical guidelines, suggest that patients with old, hyalinized Histoplasma granulomas do not benefit from further laboratory studies or antifungal therapy. The proposed grading of Histoplasma granulomas informs clinicians of the stage of resolution of an excised lesion, which informs therapeutic decisions and thus is recommended.