Pulmonary infection caused by Tropheryma whipplei in a child before hematopoietic stem cell transplantation: a case report

Background: (TW) triggers Whipple's disease (WD), a rare, chronic multisystemic infection with heterogeneous clinical presentations that can be easily overlooked, particularly Whipple's pneumonia. The advent of metagenomic next-generation sequencing (mNGS) technology applied to bronchoalveolar lavage fluid (BALF) analysis has enabled the identification of an increasing number of patients with acute pneumonia due to TW. Most reports describe symptomatic middle-aged males with cough, while asymptomatic pediatric cases remain exceptionally rare. Without adequate antibiotic therapy, WD is invariably fatal, especially in patients undergoing hematopoietic stem cell transplantation (HSCT). There is no established consensus on the optimal treatment regimen or duration, particularly for pediatric patients. Case Description: An 8-year-old boy with primary immunodeficiency due to a genetic mutation presented without respiratory symptoms. Yet, high-resolution computed tomography (HRCT) revealed nodular lesions. Initially misdiagnosed as a fungal infection, subsequent mNGS analysis of BALF identified TW as the sole pathogen, leading to a diagnosis of TW-associated pneumonia. Following a combined anti-infective therapy regimen, the patient successfully underwent the myeloablative conditioning (MAC) regimen. Neutrophil and platelet engraftment occurred promptly, with no severe transplant-related complications. Conclusions: This retrospective analysis describes a clinical scenario involving a pediatric patient who exhibited no respiratory symptoms prior to transplantation but showed characteristic nodular lesions on imaging studies, ultimately confirming acute pneumonia caused by TW. Under a combination anti-infection regimen consisting of intravenous ceftriaxone, oral doxycycline, and oral hydroxychloroquine, the child tolerated the MAC regimen well. Neutrophil and platelet engraftment proceeded without delay, and follow-up imaging confirmed complete resolution of the pulmonary lesions.