Unusual disseminated Talaromyces marneffei infection mimicking lymphoma in a non-immunosuppressed patient in East China: a case report and review of the literature

Abstract

Background: Talaromyces marneffei infection is an important opportunistic infection associated with acquired immune deficiency syndrome (AIDS). However, it is unusual in patients with non-AIDS and other non-immunosuppressed conditions. We report a case of delayed diagnosis of disseminated T. marneffei infection in non-AIDS, non-immunosuppressive and non-endemic conditions.

Case presentation: We describe a previously healthy 24-year-old man who complained of a 3-month history of intermittent diarrhea and a recent week of uncontrollable high fever. The HIV antibody test was negative. Enhanced abdominal computed tomography (CT) and integrated ¹⁸F-2-deoxy-2-fluoro-D-glucose position emission tomography/computed tomography (FDG PET/CT) both suspected malignant lymphoma. However, a large number of yeast-like cells were found in macrophages in cervical lymph node samples by hematoxylin and eosin stain and silver hexamine stain. Subsequent blood culture suggested T. marneffei infection. Metagenomic Next Generation Sequencing (mNGS) results suggested T. marneffei as the dominant pathogen. Unfortunately, the patient continued to develop acute liver failure and died due to adverse events associated with amphotericin B.

Conclusions: Early diagnosis in HIV-negative patients who are otherwise not immunosuppressed and endemic poses a serious challenge. T. marneffei infection is an FDG-avid nonmalignant condition that may lead to false-positive FDG PET/CT scans. Nevertheless, integrated FDG PET/CT is necessary in patients with fever of unknown origin in the early period to perform earlier biopsy for histopathology and culture in highly avid sites and to avoid delays in diagnosis and treatment.

Keywords: Delay in diagnosis; FDG PET/CT; Non-AIDS patient; Non-immunosuppressed patient; Talaromyces marneffei.

Fig. 1

Enhanced abdominal CT (a, b, c) showed significant lymph node enlargement (red arrows) and multiple thickening of the intestinal wall (white arrows). Colonoscopy indicated multiple ulcerations of the colon (d, white arrow)

Fig. 2

The MIP of ¹⁸F-FDG PET/CT (a) revealed multiple hypermetabolic lesions in the whole body (black arrows). Axial slices showed cervical, retroperitoneal and mesenteric lymph node enlargement (SUV_max = 11.1, white arrows) and diffusely thickened intestinal wall (SUV_max = 10.3, red arrow) on PET/CT fusion (b-d) and PET (e-g)

Fig. 3

Pathological examination showed numerous yeast-like cells in macrophages (red arrows) in cervical lymph node samples by hematoxylin and eosin stain (a, Magnification,× 1000) and silver hexamine stain (b, Magnification,× 1000). Blood culture (after 4 days incubation at 25 °C) surprisingly suggested T. marneffei infection (a). The mold was smeared for Gram staining from blood culture showing the red and rod-shaped hyphae (d, Magnification,× 1000)

Fig. 4

The proportions of the identified sequencing suggested T.marneffei as the dominant pathogen. The number of mapped reads and percentage is given in the total 43,126,523 reads. The number of microbial reads was 51,965(1.7015%), and the number of the fungal was 9692 (18.6510%). T.marneffei had the highest relative abundance at 97%, suggesting that it was the dominant pathogen (a). Sequencing of the isolated strain was conducted and a total coverage of 1.32% was obtained (b)