International Journal of Molecular and Cellular Medicine (IJMCM)

Pulmonary toxoplasmosis is a rare but potentially fatal opportunistic infection, most often reported in HIV-infected individuals. Its occurrence in non-HIV immunocompromised patients—particularly those with hematologic malignancies like multiple myeloma (MM)—is exceedingly rare and diagnostically challenging due to nonspecific clinical and radiologic features. While Toxoplasma gondii infection is typically mild in immunocompetent hosts, it can cause severe disease in immunocompromised populations. A literature review was conducted using PubMed, Scopus, and Google Scholar (January 2000–May 2025) with keywords: ‘pulmonary toxoplasmosis,’ ‘multiple myeloma,’ ‘non-HIV,’ ‘immunocompromised,’ and ‘BAL PCR.’ Only English-language case reports and reviews were included, with emphasis on studies from endemic regions and the past five years. We report a 49-year-old Iranian man with newly diagnosed IgG kappa MM who presented with fever, chills, vomiting, and dyspnea. Chest CT revealed a 4.2 × 3.8 cm consolidation in the posterior segment of the right lower lobe. T. gondii infection was confirmed via bronchoalveolar lavage (BAL) through tachyzoite detection on Giemsa stain and molecular identification using qPCR and nested PCR targeting the Gra6 gene. He showed transient clinical improvement and was discharged on hospital day 7. Unfortunately, he died at home within 48 hours due to MM progression, before anti-toxoplasmosis therapy was initiated. This case underscores the diagnostic difficulty of pulmonary toxoplasmosis in non-HIV immunocompromised patients and the importance of molecular BAL testing. Prophylactic measures such as co-trimoxazole should be considered in high-risk MM patients. Guidelines must address screening and management in this vulnerable population.