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Simultaneous Detection of 2 Types of Malignancies in a Pediatric Patient on FDG PET/CT Led to Diagnosis of Li-Fraumeni Syndrome

Ying Kan, MD, PhD, Yukun Si, MD, Wei Wang, MD, PhD, and Jigang Yang, MD, PhD

Abstract: A 17-month-old girl underwent FDG PET/CT to evaluate a right adrenal lesion, which showed abnormal 18F-FDG avidity. In addition, an un- expected lesion with mild 18F-FDG uptake was noted in the right anterior thoracic wall. Pathology demonstrated adrenocortical carcinoma in the right adrenal and rhabdosarcoma in both the left forearm and right anterior thoracic wall. Gene analysis confirmed the diagnosis of Li-Fraumeni syndrome. The present case emphasized FDG PET/CT value of showing simultaneously mul- tiple lesions in Li-Fraumeni syndrome, especially in the early stage without the gene analysis result.

Key Words: adrenocortical carcinoma, FDG PET/CT, Li-Fraumeni syndrome, rhabdomyosarcoma

(Clin Nucl Med 2022;47: 912-913)

Received for publication April 5, 2022; revision accepted April 8, 2022.

From the Department of Nuclear Medicine, Beijing Friendship Hospital of Cap- ital Medical University, Beijing, China.

Conflicts of interest and sources of funding: none declared.

Correspondence to: Jigang Yang, MD, PHD, Beijing Friendship Hospital Affiliated to Capital Medical University Beijing, 95 Yong An Road, XiCheng District, Beijing, China, 100050. E-mail: yangjigang@ccmu.edu.cn.

Copyright @ 2022 Wolters Kluwer Health, Inc. All rights reserved. ISSN: 0363-9762/22/4710-0912

DOI: 10.1097/RLU.0000000000004266

ACKNOWLEDGMENT

J.Y. was supported by the National Natural Science Foundation of China (no. 81971642, 82001861, 82102088), Capital’s Funds for Health Improvement and Research (no. 2020-2-2025), and National Key Research and Development Plan (no. 2020YFC0122000).

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FIGURE 1. Abdominal ultrasound was performed in a 17-month-old girl to determine the cause of vomiting and fever, which showed a lesion about 2.5 x 1.5 cm in the right adrenal gland, suggestive of malignancy. Consequently, an FDG PET/CT study was performed for staging. The MIP (A) showed the abnormal activity in the medial right upper abdomen (red arrow; SUVmax, 4.4) and in the left forearm (purple arrow; SUVmax, 3.5). On the axial images of the upper abdomen (B: PET, C: CT, D: fusion), the abdomen activity was located in the known right adrenal lesion (red arrows). The axial images of the left forearm (E: PET, F: CT, G: fusion) confirmed that the left forearm activity (purple arrows) was located in an ill-defined slightly hypodense region inside muscle. Unexpectedly, a minimally increased activity (green arrows) with SUVmax of 0.9 was noted in the right upper chest wall (H: PET, I: CT, J: fusion), which also corresponded to a small mild hypodense region inside the muscle. The PET/CT findings further suggested malignancy with metastases. Surgical pathology demonstrated adrenocortical carcinoma in the right adrenal. Biopsy pathology showed rhabdosarcoma in the left forearm and the right anterior thoracic wall. The genetic analysis confirmed TP53 gene mutation. The mutation site was c.375G > A, which was classified as a pathogenic variant according to the American College of Medical Genetics and Genomics standard. Gene analysis confirmed the diagnosis of Li-Fraumeni syndrome (LFS). Li-Fraumeni syndrome is a rare autosomal dominant malignancy predisposition syndrome caused by germline TP53 gene mutations. It is characterized by an increased predisposition to diverse early-onset multiple tumors. In childhood, the LFS tumor spectrum included but is not limited to osteosarcoma, adrenocortical carcinoma, central nervous system tumors, and soft tissue sarcoma, with incidence rates of 30%, 27%, 26%, and 23%, respectively.2,3 Adrenocortical carcinoma is an extremely rare pediatric malignancy, accounting for 0.2% of all childhood cancers. Germline TP53 mutations were occurring in 50% to 100% of children with adrenocortical carcinoma and decline with age.4 6 The germline mutations in TP53 tumor suppressor gene on chromosome 17p13 are widely recognized as the pathogenic gene in LFS. The LFS diagnosis is mainly based on Chompret criteria.7,8 The present case had both adrenocortical carcinoma and rhabdomyosarcoma without definitive family history, meeting the Chompret criteria of rare tumor type. Identification of related tumors and timely screening for TP53 variants are crucial for the early diagnosis of LFS.9 It is important to screen the second tumor in the suspicious patient. 18F-FDG PET/CT, as a whole-body imaging technique of the simultaneous acquisition metabolic activity combined with anatomy information, can show all lesions after 1 scan, including malignancy10-12 and benign disease.13-16 The Pediatric Cancer Working Group of the American Association for Cancer Research proposed early tumor surveillance protocols for pediatric cancer in pediatric patients with known LFS.17 Our case indicates that different malignant tumors identified on FDG PET/CT in pediatric patients without known LFS should prompt gene analysis of LFS and other syndromes that are predisposed to cancer.

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