Extrapulmonary Pneumocystis jirovecii infection in an advanced HIV-infected patient: A case report and literature review

BACKGROUND: Pneumocystis jirovecii infection is the most common opportunistic infection that causes pneumonia in human immunodeficiency virus (HIV)-infected patients; however, extrapulmonary P. jirovecii infection is extremely rare after the use of antiretroviral therapy. Here, we present the second reported case of paraspinal mass caused by P. jirovecii infection in an advanced HIV-infected patient. CASE PRESENTATION: A 45-year-old woman presented with dyspnea on exertion, and significant weight loss within the preceding 4 months. Initial complete blood count (CBC) findings revealed pancytopenia with a hemoglobin (Hb) level of 8.9 g/dL, a white blood cell (WBC) count of 2180 cells/mm(3) with 68% neutrophils, and a platelet count of 106,000 cells/mm(3). Anti-HIV was positive with an absolute cluster of differentiation 4 (CD4) count of 16 cells/ mm(3). A computed tomography scan of the chest revealed an enhancing soft tissue mass-like lesion at the right paravertebral region (T5-T10 level) and a thick-walled cavity lesion at the left lower lung. A CT-guided biopsy of the paravertebral mass was performed and histopathology revealed granulomatous inflammation consisting of dense aggregates of epithelioid cells and macrophages, and scattered foci of pink foamy to granular materials amidst the granulomatous inflammation. Gomori methenamine silver (GMS) staining revealed thin cystic-like structures (ascus) that were observed to be morphologically consistent with P. jirovecii. Molecular identification and DNA sequencing from the paraspinal mass was 100% identical to P. Jirovecii. The patient was successfully treated with oral trimethoprim-sulfamethoxazole for 3 weeks and antiretroviral therapy (ART) with tenofovir (TDF), lamivudine (3TC), and dolutegravir (DTG). A follow-up CT scan of the chest at 2 months after treatment showed a decrease in sizes of both the paravertebral mass and the cavitary lung lesion. CONCLUSIONS: Extrapulmonary pneumocystosis (EPCP) has become an extremely rare condition in HIV-infected patients after the widespread use of ART. EPCP should be considered in ART-naive HIV-infected patients suspected of having or diagnosed with Pneumocystis jirovecii pneumonia who present with atypical symptoms and/or signs. Histopathologic examination with GMS staining of affected tissue is necessary for the diagnosis of EPCP.