대한흉부영상의학회 Weekly Chest Cases

Case No : 1457 Date 2025-09-22

Courtesy of Hyun-ju Lim, Kun Young Lim, Hyae Young Kim / National Cancer Center
Age/Sex 86 / F
Chief ComplaintIncidental finding during work-up for right renal mass

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Diagnosis With Brief Discussion

Diagnosis: Ectopic thymoma
Radiologic Findings: Fig 1. Chest PA shows mild right paratracheal bulging.
Fig 2-3. Chest CT reveals an enhancing paratracheal mass with internal focal low attenuating area. This lesion is measured about 5.1 x 4.1 cm in diameter on coronal image.
Fig 4. PET CT shows intense FDG uptake in right paratracheal mass.
Brief Review: The patient underwent EBUS-trasbronchial needle biopsy for right paratracheal mass. Thymoma was confirmed.
Thymomas are the most common neoplasm of the anterior mediastinum. However, they are also known to arise in ectopic locations including the neck, middle or posterior mediastinum, the lung, base of the skull and the pleural cavity. Ectopic thymomas, which accounts for only 4% of the thymoma are thought to arise from the distributed thymic tissue that has failed to migrate into the anterosuperior mediastinum. Another hypothesis is that ectopic thymoma originates from stem cells.
The middle mediastinal ectopic thymoma is are very rare. According to the previous report on mediastinal ectopic thymoma, the average age of onset was 59.2 years, with no significant difference in gender.
Differential diagnosis of middle mediastinal masses includes lymphadenopathy (malignant lymphoma,
sarcoidosis, Castleman’s disease, and metastasis), neurogenic tumors and mediastinal goiters.
References: 1. Zhou Q, Han L, Ke X, Zhou J. Ectopic thymoma: Retrospective analysis of eight cases with clinical features and computed tomography findings. Clinical imaging 2020;60:153-159.
2. Yajima T, Mogi A, Shimizu T, Kosaka T, Nagashima T, Ohtaki Y et al. Ectopic thymoma in the paratracheal region of the middle mediastinum: a rare case report and literature review. BMC Res Notes 2018;11:256
3. Sato M, Nakayama H, Fukukura Y, Nakajo M, Nagata T, Tabata K. Ectopic middle mediastinal thymoma: A rare case report and review of the literature. Med. J. Kagoshima Univ., 2012;64:13-20
4. Tuan P, Duc N. Ectopic thymoma in the middle mediastinum: A case report and literature review. Clin Ter 2021;172:94-98
Keywords

No. of Applicants : 72

▶ Correct Answer : 4/72, 5.6%

- Secomedic Hospital , Japan FUMINORI MIYOSHI
- , Japan MASAMICHI IWAI
- Kantou Rousai Hospital , Japan KAORU SUMIDA
- the first affiliatited hospital of nanjing medical univercity , China HAI XU

▶ Correct Answer as Differential Diagnosis : 13/72, 18.1%

- Shiga University of Medical Science , Japan AKITOSHI INOUE
- Kyoto University , Japan AKIHIKO SAKATA
- Chonbuk National University Hospital , Korea (South) EUNCHONG LEE
- Chonbuk National University Hospital , Korea (South) YONG HWAN JO
- Seoul Medical Center , Korea (South) HYUK GI HONG
- QATIF CENTRAL HOSPITAL , Saudi Arabia HANI M ALSALAM
- University of Yamanashi , Japan HIROYUKI MORISAKA
- , Japan YOSHIKI ISHII
- Inje University Pusan Paik Hospital , Korea (South) JIYEON HAN
- Jichi Medical University, School of Medicine , Japan MITSURU MATSUKI
- Korea University Anam Hospital , Korea (South) KYU-CHONG LEE
- , Japan MATSUNO MAI
- Kyoto University , Japan SHO KOYASU

▶ Semi-Correct Answer : 10/72, 13.9%

- , Japan SUZUNE TSUKAMOTO
- IUHW Narita Hospital , Japan ISSEI FUKUDA
- Kyoto City Hospital , Japan YUSUKE UTSUNOMIYA
- Samsung Medical Center , Korea (South) HYUNGIN PARK
- The University of Tokyo Hospital , Japan TOSHIHIRO FURUTA
- Japanese Red Cross Otsu Hospital , Japan JUN YOSHIDA
- , Korea (South) HYOUNG YEOB KIM
- Chonnam National University Hospital , Korea (South) SANGYONG BAK
- Chonnam National University Hospital , Korea (South) SOMIN LEE
- Fukuoka university , Japan KEISUKE SATO

대한흉부영상의학회 Korean Society of Thoracic Radiology

Archive of Old Cases

Case No : 1457 Date 2025-09-22

Discussion

No. of Applicants : 72