SMARCA4-deficient thoracic tumor detected by [18F]FDG PET/CT

Tsubasa Okazaki,Yasunari Miyazaki,Kota Yokoyama,Takayuki Honda,Susumu Kirimura,Jyunichi Tsuchiya,Yuya Ishikawa,Ukihide Tateishi

doi:10.1186/s41824-021-00102-5

Tsubasa Okazaki, Yasunari Miyazaki + Show 6 more

Open Access

https://doi.org/10.1186/s41824-021-00102-5

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Abstract

BackgroundSMARCA4-deficient thoracic tumor (SMARCA4-DTT) is a distinct entity of undifferentiated thoracic malignancies newly introduced in 2015. Due to its unique clinical characteristic with aggressive thoracic tumor mostly observed in heavy smoker man with emphysema, with poor prognosis, many physicians are becoming increasingly aware of the disease; however, reports on 2-deoxy-2-[18F] fluoroglucose positron emission tomography/computed tomography ([18F]FDG PET/CT) have been limited; thus, this disease is not yet widely known to nuclear medicine clinicians. As a first step in discussing the usefulness of [18F]FDG PET/CT for this disease, we present a case in which [18F]FDG PET/CT played a clinically important role.CaseA 74-year-old heavy smoker man with an anamnesis of severe emphysema characterized by pleural thickening and abnormal enhancement in CT underwent 18F-FDG PET/CT for further examination. [18F]FDG-avid pleural nodules infiltrating into the chest wall were detected and pathologically diagnosed as SMARCA4-DTT with biopsy.ConclusionSMARCA4-deficient thoracic tumor should be considered in a [18F]FDG-avid aggressive thoracic tumor in heavy smoker men with emphysema.

Highlights

SMARCA4-deficient thoracic tumor (SMARCA4-DTT) is a distinct entity of undifferentiated thoracic malignancies newly introduced in 2015
We report an educational case of SMAR CA4-DTT, showing high activity on [18F]FDG Positron emission tomography (PET)/Computed tomography (CT) that demonstrated chest wall infiltration, which was difficult to differentiate from other thoracic malignancies
He was diagnosed with mild pleural thickening 6 months before presentation, and contrast-enhanced CT revealed worsening of pleural thickening and abnormal enhancement infiltrating into the right anterior chest wall (Fig. 1; a, b: yellow arrows) with severe emphysema (c), resulting in a suspected diagnosis of malignant pleural mesothelioma

Summary

Background

SMARCA4-deficient thoracic tumor (SMARCA4-DTT) is a distinct entity of undifferentiated thoracic malignancies newly introduced by Le Loarer et al in 2015. SMAR CA4-DTT is characterized by loss of SMARCA4, showing undifferentiated round cell or rhabdoid morphology presenting as aggressive behavior with compressive or infiltrative tumors mostly involving the mediastinum, lung, and/or pleura (Le Loarer et al 2015; Crombé et al 2019; Yoshida et al 2017). We report an educational case of SMAR CA4-DTT, showing high activity on [18F]FDG PET/CT that demonstrated chest wall infiltration, which was difficult to differentiate from other thoracic malignancies. Case presentation A 74-year-old heavy smoker man with an anamnesis of severe emphysema presented with a 2-week history of right chest pain He was diagnosed with mild pleural thickening 6 months before presentation, and contrast-enhanced CT revealed worsening of pleural thickening and abnormal enhancement infiltrating into the right anterior chest wall (Fig. 1; a, b: yellow arrows) with severe emphysema (c), resulting in a suspected diagnosis of malignant pleural mesothelioma. Chemotherapy was initiated but resulted only in a temporary response, and the patient’s condition worsened in several months

Discussion

Conclusion