key: cord-0860122-8hw907wc
authors: Manda, Divya; Sen, Ishita; Thakral, Parul; Das, Subha Shankar; CB, Virupakshappa; Malik, Dharmender
title: Invasive Fungal Infection in COVID-19–Recovered Patient Detected on (18)F-FDG–Labeled Leukocytes PET/CT Scan
date: 2021-07-28
journal: Clin Nucl Med
DOI: 10.1097/rlu.0000000000003852
sha: fbd9a2cd07e69e665e6a7e0e9ff065286d07a9ed
doc_id: 860122
cord_uid: 8hw907wc

Occurrence of invasive fungal infections has gained significant attention during recent times in patients with COVID-19. Patients with severe form of COVID-19, such as those treated in the intensive care unit with prolonged steroid use, are particularly vulnerable to secondary bacterial and fungal infections. Disseminated systemic mycosis is a life-threatening condition, especially in immunocompromised patients. Here, we report a case of a recovered severe COVID-19 patient, who presented with persistent fever. (18)F-FDG–labeled leukocyte scan revealed focal accumulation of radiotracer in the small intestine and right lung lower lobe. Subsequently, performed biopsy revealed mucormycosis.

A 40-year-old woman presented to the hospital with chief complaint of persistent fever since 15 days. Patient was an old-treated case of severe form of COVID-19 requiring intensive care unit admission and had received high dose of steroid for a duration of 10 days. The patient also had prior history of renal transplant recipient 8 months back. Her blood culture was negative for growth of microorganism during hospital stay. 18 F-FDG-labeled leukocytes PET/CT scan (MIP image, A) was performed for detection of occult site of infection, which revealed focal accumulation of radiotracer in a thick-walled fibrocavitatory lesion in the posterior basal segment of the right lung lower lobe with perilesional ground glass haziness (B and C, arrow) in terminal ileum and caecum (D-H, dotted arrowhead), suggestive of disseminated infection.

Subsequently performed PET/CT-guided biopsy from tracer-avid lesion in terminal ilium demonstrates nonpigmented pauci septate, ribbon-like hyphae (A and B), which were found to be positive for MGG stains (Â40 and Â100, C and D), suggestive of mucormycosis. There is a diverse range of bacterial and fungal infections that may coexist with possible association with a preexisting morbidity (diabetes mellitus, lung disease, postrenal transplant) or may develop as a hospital-acquired infection. 1 Mucormycosis is an emerging life-threatening invasive fungal infection, which has been increasing in recent times in severe form of COVID-19-recovered patients. 2 Invasive fungal infection often poses a huge diagnostic challenge, especially in immunocompromised patients resulting in significant morbidity and mortality. 3 Invasive fungal infection can affect any part of body, and imaging plays a crucial role in its management. PET/CT, as a whole-body imaging procedure, enables the detection of invasive fungal infection at different sites of the body in a single imaging session. 4 18 F-FDG-labeled autologous leukocytes have been used for the detection of occult acute pyogenic infections. 5 There is, however, limited experience using FDG-labeled leukocytes for detection of invasive fungal infections. The concept of labeled leukocyte imaging is based on the mechanisms of chemotaxis exerted on activated leukocytes by chemoattractants. The short half-life of 18 F-labeled autologous leukocytes actually allows us to visualize neutrophil margination in response to infection rather than neutrophil migration. 6 The activated leukocytes are also known to express increased glucose transporter proteins on the cell membrane, which in turn leads to focal accumulation of the radiotracer at infected site. 7 Most pathogenic fungi are susceptible to neutrophil killing, and neutrophils are professional phagocytes of the innate immune system. Neutrophils enter the site of infection after a chemokine gradient engulf and intracellularly toxify the microbe, secrete antimicrobial proteins into the surrounding, or release cytokines to recruit other immune cells. 8 The index case highlights the utility of 18 F-FDG-labeled autologous leukocytes whole-body scan to serve as a powerful diagnostic tool for precise localization of sites of occult fungal infections.

Infectious disease transmission in solid organ transplantation: donor evaluation, recipient risk, and outcomes of transmission

Mucormycosis in renal transplant recipients: review of 174 reported cases

ESCMID and ECMM joint clinical guidelines for the diagnosis and management of mucormycosis 2013

The added value of [ 18 F] FDG PET/CT in the management of invasive fungal infections

PET/CT with 18 F-FDG-labeled autologous leukocytes for the diagnosis of infected fluid collections in acute pancreatitis

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Imaging infection with 18 F-FDGlabeled leukocyte PET/CT: initial experience in 21 patients

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