To analyze the clinical data of one case with pulmonary cavitary nodule caused by Tropheryma whipplei(T.whipplei) infection and review the literature, aiming to improve the clinical understanding of pulmonary infection caused by T. whipplei.

A case of T. whipplei lung infection was reviewed and summarized, including the patient′s medical history, laboratory test results, CT imaging findings, metagenomic next generation sequencing (mNGS) results, treatment process, and therapeutic outcomes. The case was also compared with relevant literature on T. whipplei lung infections.

The study enrolled a female 39-year-old urban residents with a history of feline feline contact.Laboratory and auxiliary examinations revealed the following: white blood cell count 6.35×10⁹/L, absolute neutrophil count 3.5×10⁹/L, absolute lymphocyte count 2.02×10⁹/L, absolute monocyte count 0.58×10⁹/L, absolute eosinophil count 0.21×10⁹/L, hemoglobin 118 g/L, C-reactive protein (CRP) 0.4 mg/L. Coagulation panel: prothrombin time (PT) 11.0 sec, activated partial thromboplastin time (APTT) 28.7 sec, thrombin time (TT) 14.7 sec, fibrinogen (FBG) 2.45 g/L. Metagenomic next-generation sequencing (mNGS) of bronchoalveolar lavage fluid (BALF) indicated: Gram-positive bacteria: Tropheryma whipplei, sequence count 1179, relative abundance 14.60%; Fungus: Candida parapsilosis, sequence count 18, relative abundance 0.16%; DNA virus: Human betaherpesvirus 7, sequence count 3, relative abundance 2.12%. Chest CT showed a solitary cavitary nodule in the left lower lung as the initial presentation. The patient was diagnosed with Tropheryma whipplei pulmonary infection via mNGS and received a standardized 3-month course of oral cotrimoxazole (trimethoprim-sulfamethoxazole) anti-infective therapy. Following treatment, the cavitary nodule diameter decreased from 18 mm×13 mm to 11 mm×6 mm, indicating effective treatment response.

Bronchoalveolar lavage fluid mNGS is an effective diagnostic method for pulmonary infections caused by T. whipplei. Patients without immunosuppression who present solely with lung cavities or nodules should be vigilant for T. whipplei infection in clinical. Oral treatment with compound sulfamethoxazole has shown significant therapeutic effects.