Talaromyces marneffei mimics lung cancer along with mediastinal and hilar lymph node metastases: a case description

Sep 30, 2026

Uploaded by Sarah

Dimorphic fungus Talaromyces marneffei can be radiologically confused with peripheral lung cancer, especially when disease is limited to the lungs and appears as a tumor-like mass. A 56-year-old immunocompetent male smoker with prior consumption of cooked wild bamboo rat presented with persistent cough and an irregular right lung mass. Enhanced CT and 18F-FDG PET showed a hypermetabolic lesion with enlarged supraclavicular, mediastinal, and hilar lymph nodes, raising suspicion of malignancy with metastases. Biopsy and bronchoscopy with BALF mNGS and cultures clarified the diagnosis and guided management.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages6

Reading Time15 min

AccessFree to download

Introduction

Case description

Imaging findings

Laboratory results and tumor markers

Biopsies and histopathology

Bronchoalveolar lavage and mNGS

Letter to the Editor Talaromyces marneffei mimics lung cancer along with mediastinaland hilar lymph node metastases: a case description Lichang Chen\#, Qianxiang Wei\#, Xiping Wu, Huizhen Fan Department of Pulmonary and Critical Care Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou, China \#These authors contributed equally to this work. Correspondence to: Huizhen Fan, MD. Department of Pulmonary and Critical Care Medicine, Zhujiang Hospital, Southern Medical University, Guangzhou 510220, China. Email: [110851512@qq.com](110851512@qq.com). Submitted Jan 17, 2025. Accepted for publication Nov 04, 2025. Published online Dec 31, 2025. doi: 10.21037/qims-2025-146 View this article at: [https://dx.doi.org/10.21037/qims-2025-146](https://dx.doi.org/10.21037/qims-2025-146) Introduction Talaromyces marneffei (T. marneffei) is a dimorphic fungus that is endemic to Southeast Asian countries (1), and bamboo rats are its natural hosts. T. marneffei infections rarely occur in immunocompetent individuals. Owing to the difficulty in distinguishing T. marneffei infection from peripheral lung cancer when the infected area is restricted to the lungs and the formation of a pulmonary tumor is observed, T. marneffei infection is frequently misdiagnosed as peripheral lung cancer owing to radiographic similarities, as various fungal infections can radiologically mimic malignancies (2) . Here, we discuss the presentation and diagnosis of T. marneffei infection in an immunocompetent male to improve physicians’ understanding of the disease. Case description An immunocompetent 56-year-old male smoker who had previously consumed a cooked wild bamboo rat presented with a cough that had persisted for one month and underwent enhanced computed tomography (CT) imaging (Figure 1A,1B), which revealed a pulmonary massin the right lung (arrow) . The mass exhibited irregular characteristics, including spicules, lobulation, or cavities, and certain areas exhibited ground glass density. These features implied unclear margins and a relatively invasive nature. Due to the ineffectiveness of antibacterial therapy, the mass was suspected to be a tumor. The patient was subsequently admitted to our hospital and underwent fluorine-18 flu orodeoxyglucose positron emission tomography ( 18F-FDG PET) imaging. The scan revealed a hypermetabolic mass in the upper lobe of the right lung as well as enlargement of the clavicular area (Figure 1C, arrows) . The larger segment measured approximately 7.6 cm × 7.6 cm, and the margins exhibited lobulation and delicate spicules. FDG uptake was evident, with a maximum standardized uptake value (SUVmax) of approximately 17.62. The enlargement of multiple lymph nodes was observed in the right supraclavicular region, mediastinum (stations 1R, 3R, 3A, 4R, 7, and 8), and right hilar region. Focal FDG uptake was considered to be pathological, with the largest lesion located in mediastinal station 4R, measuring approximately 2.4 cm × 1.8 cm (Figure 1D, arrows), and demonstrating a SUVmax value of 8.95. These findings suggest a high probability of malignancy and the presence of lung cancer along with mediastinal and hilar lymph node metastases. Laboratory examinations revealed a white blood cell count of 12. 85×109/L, an absolute neutrophil count of 10. 15×109/L, the absolute lymphocyte count is 1. 73×109/L, an absolute eosinophil count of 0. 15×109/L, an absolute basophil count of 0. 03×109/L, a procalcitonin level of 0.06 μg/L, and a hypersensitive C-reactive protein level of 152.31 mg/L. However, the levels of the tumor markers carcinoembryonic antigen, cytokeratin 19 fragment, and neuron-specific enolase were not elevated. In addition, the patient underwent two CT-guided lung nodule biopsies and one biopsy of the lymph node in the right clavicular region. Histopathological examination of the © AME Publishing Company. Quant Imaging Med Surg 2026;16(1):106 | [https://dx.doi.org/10.21037/qims-2025-146

FAQs

Why can Talaromyces marneffei infection be mistaken for lung cancer in this case?

The lesion showed tumor-like imaging features and radiographic similarities to malignancy, especially when restricted to the lungs with masses that can mimic peripheral lung cancer.

What imaging findings suggested malignancy and lymph node metastases?

Enhanced CT showed an irregular pulmonary mass, and 18F-FDG PET revealed a hypermetabolic mass plus enlarged lymph nodes in mediastinal and hilar stations with high FDG uptake values.

How was the diagnosis clarified after initial suspicion of cancer?

Histopathological examination from lung and lymph node biopsies showed benign findings, and bronchoalveolar lavage fluid was tested using metagenomic next-generation sequencing (mNGS) and conventional bacterial and fungal culture.

Sep 30, 2026

Uploaded by Sarah