Abstract
AB006. Two cases of mediastinal germ cell tumor with somatic-type malignancy with neuroendocrine tumor
Tomoki Nishimura, Masanori Shimomura, Satoru Okada, Tatsuo Furuya, Chiaki Nakazono, Sae Kitamura, Saki Hanafusa, Kyosei Takahashi, Masayoshi Inoue
Division of Thoracic Surgery, Department of Surgery, Kyoto Prefectural University of Medicine, Kyoto, Japan
Correspondence to: Tomoki Nishimura, MD. Division of Thoracic Surgery, Department of Surgery, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan. Email: nsmrtmk@koto.kpu-m.ac.jp.
Background: Germ cell tumors with somatic-type malignancy (GCTSM) are defined as germ cell tumors with malignant neoplasm component resembling that observed at somatic sites. GCTSM, including neuroendocrine tumors (NETs), are relatively rare, and difficult to diagnose preoperatively. Herein, we present two cases of mediastinal GCTSM with NET, including nodules that show contrast enhancement on contrast-enhanced computed tomography (CT) or 18F-fluorodeoxy-glucose (18F-FDG) accumulation on positron emission tomography (PET) scans.
Case Description: (I) Case 1: the patient was an asymptomatic 46-year-old male. Chest CT revealed 3 cm tumor in the anterior mediastinum. PET scans showed 18F-FDG accumulation [standardized uptake value (SUV) =2.01] in a portion of the tumor. Serum tumor marker levels were within normal ranges, and magnetic resonance imaging (MRI) showed solid component in the cystic region. Robot-assisted total thymectomy was performed. Histologically, mature teratoma and part of the cyst wall (maximum diameter: 7 mm), including cuboidal atypical cells with round nuclei and rosette-like structures, were observed. Immunohistochemically, the atypical cells were positive for CD56, synaptophysin, and chromogranin A. The Ki-67 index was <1%. The tumor was diagnosed as GCTSM with NET, grade 1. The patient is currently alive 2 months after surgery without recurrence. (II) Case 2: the patient was a 47-year-old female who had no symptoms. Contrast-enhanced chest CT showed 6.5 cm anterior mediastinal tumor with rapid growth for 2 months and heterogeneous contrast effect in the nodule. Serum tumor marker levels were within the normal range, and MRI showed no invasion of the aorta or lungs. Robot-assisted total thymectomy was performed. Histologically, mature teratoma and 5 mm-sized endocrine cell proliferation nests were observed in the pancreatic tissue within the cyst wall. Immunohistochemically, the atypical cells were positive for INSM1, synaptophysin, and chromogranin A. The tumor had four mitoses per ten high power fields, and the Ki-67 index was 10%. The tumor was diagnosed as GCTSM with NET, grade 2. The patient is currently alive 6 months after surgery without recurrence.
Conclusions: In cases of suspected teratoma, contrast-enhanced CT or PET scans could be useful for differentiating GCTSM including small malignant nodules. The procedure and approach should be aimed at complete resection in such cases.
Keywords: Germ cell tumor with somatic-type tumor; positron emission tomography-scan (PET-scan); contrast-enhanced computed tomography (contrast-enhanced CT); case report
Acknowledgments
Funding: None.
Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://med.amegroups.com/article/view/10.21037/med-24-ab006/coif). The authors have no conflicts of interest to declare.
Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patients for the publication of this case report. A copy of the written consent is available for review by the editorial office of this journal.
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doi: 10.21037/med-24-ab006
Cite this abstract as: Nishimura T, Shimomura M, Okada S, Furuya T, Nakazono C, Kitamura S, Hanafusa S, Takahashi K, Inoue M. AB006. Two cases of mediastinal germ cell tumor with somatic-type malignancy with neuroendocrine tumor. Mediastinum 2024;8:AB006.
