The relationship between organising pneumonia and invasive mould disease in patients with haematologic malignancy

Abstract

Background: Organising pneumonia (OP) is reported in patients with haematologic malignancy suspected of having invasive mould disease, yet little is known about this relationship.

Objective: To investigate molecular evidence of invasive mould pneumonia in paraffin-embedded lung tissues from histologically diagnosed OP patients with suspected invasive mould pneumonia.

Patients/methods: Patients with haematologic malignancy suspected to have invasive pulmonary mould disease who underwent lung biopsy at a tertiary hospital, Seoul, South Korea, between 2008 and 2020, were retrospectively reviewed. To find molecular evidence of fungal infection, PCR assay was used to detect Aspergillus- and Mucorales-specific DNA within OP lung tissue sections.

Results: Forty-seven patients with suspected invasive mould pneumonia underwent lung biopsy and 15 (32%) were histologically diagnosed as OP without any evidence of fungal hyphae. Of these 15 patients, 3 (20%) received allogenic haematopoietic stem cell transplantation prior to developing OP. Before biopsy, 2 and 13 patients had probably and possible invasive mould disease, respectively. The median antifungal treatment length was 81 [8-114] days, and the median steroid treatment dosage was 0.35 mg/kg/day for 36 days (methylprednisolone equivalent doses), respectively. After biopsy, three patients with possible invasive mould infection revealed probable invasive pulmonary aspergillosis. From the 15 paraffin-embedded lung tissues, 6 (40%) exhibited positive PCR assay results for detecting Aspergillus- and Mucorales-specific DNA.

Conclusions: More than one third of OP cases in patients with suspected invasive mould pneumonia exhibited molecular evidence of invasive mould infection by fungus-specific PCR in lung tissues, likely associated with concurrent or prior fungal infection.