Histoplasma in Explanted Tissue of Lung Transplant Recipients (LTRs) from a Moderate Endemic Region

Purpose There is a paucity of studies assessing the incidental finding of histoplasmosis in the explanted tissue from lung transplant recipients (LTRs). Thus, there are currently no recommendations for the management of Histoplasmosis in the explanted organ of LTRs. This study aims to describe our experience in the management of histopathologic evidence of Histoplasmosis, encountered unexpectedly in the explanted tissue of LTRs at the time of transplantation. Methods We retrospectively identified LTRs at the Toronto program from 2010-2017, with histopathologic evidence of Histoplasma in the lung explanted tissue. Results Of 810 LTRs, 6 recipients had Histoplasmosis in the explanted organ (incidence 0.75%, clinical characteristics shown in Table 1. None of the 6 patients had a previously known diagnosis of Histoplasmosis. All of them lived in Ontario, Canada, and only one had traveled abroad in the past five years (to Florida, USA). All 6 patients had lung parenchyma and lymph node involvement in the histopathology findings, with necrotizing granulomas and fungal spores compatible with Histoplasmosis. All patients received antifungal pre-emptive therapy after transplant: 4 (67%) Itraconazole and 2 (33%) voriconazole for a mean duration of 4.8 months (IQR, 2.82-8.1 months). No patients in this group developed posttransplant Histoplasmosis (median follow up of 3.0 years [IQR 2.0-4.1 years]). Conclusion The unexpected finding of histoplasmosis in the explanted tissue of LTRs was infrequent (0.75%) in this non-endemic area. None of the patients, all of whom received antifungal therapy, developed active Histoplasmosis post-transplant.