A case of pulmonary nodular lesion caused by Tropheryma Whipplei infection: case report and literature review

Background Tropheryma Whipplei ( T. whipplei ) is a Gram-positive, aerobic bacillus belonging to the genus Actinobacter. It can cause Whipple's disease (WD) involving multiple systems, and when it affects the lungs, it can lead to pneumonia. At present, there is no consensus among experts regarding T. whipplei pneumonia. Its clinical manifestations and imaging features lack specificity, which can easily lead to misdiagnosis and missed diagnosis. Case presentation: A 69-year-old male patient presented with intermittent right-sided chest pain and coughing with expectoration. Initially, based on the patient's chest imaging examination, we considered a high possibility of a malignant lung tumor. After a series of comprehensive examinations and treatments, we ruled out the tumor and confirmed that it was an infectious lesion. The positron emission tomography/computed tomography (PET/CT) examination revealed a marked increase in ¹⁸ F-fluorodeoxyglucose ( ¹⁸ F-FDG) metabolism in this pulmonary lesion. This lesion blocked the bronchial opening in the outer basal segment of the right lower lobe of the lung. From this location, we obtained bronchoalveolar lavage fluid (BALF) and bronchial mucosal biopsy tissues, and we detected the T. whipplei through targeted next-generation sequencing technology (tNGS). No tumor cells were found in the pathological results of the bronchial mucosa biopsy tissues and the biopsy tissues from the lesion sites. After six months of anti-infection treatment for T. whipplei , the original lung nodules had significantly shrunk and disappeared. We conducted a literature review of published case reports with relatively complete data, and analyzed and summarized the clinical involvement, chest imaging manifestations and diagnostic methods of lung infections caused by T. whipplei . Conclusions Pulmonary nodules may be the most common chest imaging manifestation of T. whipplei infection involving the lungs. Coughing is the most common respiratory symptom. The diagnostic technology of tNGS has improved the diagnostic efficiency of pathogenic microorganisms. PET/CT can be used as a potential auxiliary diagnostic tool for pulmonary nodules caused by T. whipplei infection.