Comparative histopathological and immunohistochemical features of central nervous system and pulmonary tuberculosis: an exploratory retrospective study

Central nervous system tuberculosis (CNS-TB) is a rare and particularly severe form of extrapulmonary tuberculosis (EPTB). Early diagnosis and precise treatment are crucial in managing this condition. Pathological and immunohistochemical features may differ between CNS-TB and pulmonary tuberculosis (PTB). This study included 9 patients of CNS-TB, and analyzed their clinical manifestations, pathological features, and the immunohistochemical(IHC) features. The findings were then compared with PTB to explore the similarities and differences in how tuberculosis manifests in the brain versus the lungs. However, CNS-TB tissue specimens are difficult to obtain, limiting our sample size. Additionally, several patients received preoperative anti-tuberculosis therapy and short-course corticosteroids before sampling. Given these baseline differences, intergroup comparisons should be interpreted cautiously. Unlike patients with isolated PTB, those with CNS-TB frequently present with multisystem tuberculosis involving the lungs. Typical tuberculosis manifestations including fever, anorexia, weight loss, dizziness and lymphadenopathy did not differ between groups. Likewise, CBC parameters (hemoglobin, total white blood cell count, absolute neutrophil count and lymphocyte count) were comparable between CNS-TB and PTB groups. In this small cohort, general pathological features such as granulomas and caseous necrosis were similar in CNS-TB and PTB lesions. We further compared their IHC profiles. This exploratory analysis revealed that CNS-TB lesions harbored significantly fewer CD34 + microvessels, CD4 + T cells and CD38 + cells relative to PTB lesions, while CD56 + cells were mildly elevated in CNS-TB. No marked intergroup differences were noted for other immune cell subsets. Collectively, pathological characteristics and immune cell infiltration may differ between CNS-TB and PTB. Owing to the absence of normal brain and lung tissue controls, our findings warrant cautious interpretation. Finally, we performed exploratory drug-resistance analysis using remaining specimens from four patients in each group and observed similar resistance-associated mutation profiles between CNS-TB and PTB lesions.