Granulomatous Lung Nodule Mimicking as Metastasis on F18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in a Case of Adrenocortical Carcinoma
Abstract
A variety of fungal pulmonary infections can produce radiologic findings that mimic malignancy. Distinguishing these infectious lesions from malignancy remains challenging for physicians. We describe one such case where fungal lung nodule mimicked metastasis on fluorodeoxyglucose positron emission tomography/computed tomography scan.
Keywords: Fluorodeoxyglucose positron emission tomography-computed tomography, fungal granuloma, lung nodule
Explaination
A 25-year-old male, presented with complaints of abdominal pain, fever, and vomiting. Computed tomography (CT) scan revealed 6 cm sized left adrenal mass, underwent left adrenal mass excision, histopathology revealed adrenocortical carcinoma. Postoperative 18F Fluorodeoxyglucose positron emission tomography (FDG PET/ CT) revealed focal increased FDG uptake in the right lung, upper lobe nodule and on axial images, with SUV max-7.08 [Figure 1]. The imaging findings were suspicious for a metastatic
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nodule. Video-assisted-thoracoscopic metastatectomy of the nodule with completion adrenalectomy was done. Histopathology from lung nodules revealed necrotic granulomatous inflammation with giant cells suggestive of fungal infection with no evidence of malignancy. Special stain photomicrographs revealed yeast-like organisms suggestive of Cryptococcus [Figure 1d]. The infectious agents that mimic malignancy or metastases in the lung include bacteria (Fusobacterium, Pseudomonas, Streptococcus), mycobacterium (Mycobacterium tuberculosis, Mycobacterium kansasii), parasites (Dirofilaria), fungi, and rarely, viruses (Cytomegalovirus).[1] Fungal infections that mimic malignancy include coccidioidomycosis, histoplasmosis, aspergillosis, North American blastomycosis, and cryptococcosis.[2] An SUV of 2.5 has been traditionally used as a cut-off value for differentiating malignancy from infection; but in pulmonary cryptococcosis, the SUV may vary widely, from mild to marked uptake and thus these findings indicate that FDG PET/CT is of limited value in differentiating cryptococcosis from malignancy.[3] In conclusion, such FDG-avid lung nodules pose quite a diagnostic challenge in a known case of malignancy and thus should always be correlated with a proper histopathological and microbiological evaluation.
How to cite this article: Gosavi A, Agrawal A, Menon S, Purandare N, Shah S, Puranik A, et al. Granulomatous lung nodule mimicking as metastasis on F18 fluorodeoxyglucose positron emission tomography/computed tomography in a case of adrenocortical carcinoma. Indian J Nucl Med 2021;36:453-4.
Atul Gosavi, Archi Agrawal, Santosh Menon1, Nilendu Purandare, Sneha Shah, Ameya Puranik, Venkatesh Rangarajan
Departments of Nuclear Medicine and Molecular Imaging and ‘Pathology, Tata Memorial Hospital, Homi Bhabha National Institute, Mumbai, Maharashtra, India
Address for correspondence:
Dr. Archi Agrawal, Department of Nuclear Medicine and Molecular Imaging, Tata Memorial Hospital, Homi Bhabha National Institute, E. Borges Road, Parel, Mumbai - 400 012, Maharashtra, India. E-mail: drarchi23@gmail.com
Received: 08-04-2021 Accepted: 09-06-2021 Published: 15-12-2021
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Website: www.ijnm.in
DOI: 10.4103/ijnm.ijnm_48_21
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References
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