대한흉부영상의학회 Weekly Chest Cases

Case No : 1198 Date 2020-10-11

Courtesy of Jae Min Shin / Gangnam Severance Hospital, Yonsei University Health System
Age/Sex 49 / F
Chief ComplaintNo specific symptom

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Diagnosis With Brief Discussion

Diagnosis: Schwannoma (with cystic change)
Radiologic Findings: Fig 1. Chest PA shows mass like shadow in left paraaortic area.
Fig 2-4. CT scans reveal well-circumscribed mass (pre-contrast:10-20HU) with heterogeneous enhancement (contrast-enhanced:10-60HU) in left anterior mediastinum, abutting aortic arch. This lesion is measured about 4.0 X 4.5 X 5.8 cm in diameter.
Fig 5. The mass demonstrates iso- to hypointense signal intensity on T1-weighted images, hyperintense signal intensity on T2-weighted images and heterogeneous enhancement on contrast-enhanced T1-weighted images.
Brief Review: Schwannoma is also known as neurilemmoma, neurinoma, or perineural fibroblastoma. It is a benign tumor of Schwann cell origin and is the most common tumor of peripheral nerves. It is arising from the neural sheath Schwann cells of the peripheral, cranial, or autonomic nerves.
Neurogenic tumors comprise 9% of mediastinal masses in adults and 29% in children. Schwannoma is the most common (about 50%) mediastinal neurogenic tumor. A high proportion of posterior mediastinal masses are neurogenic. Approximately 80% of the lesions found in the posterior compartment were reported to be neurogenic tumors in the previous study [1]. Neurogenic tumors less commonly occur in the anterior and middle compartments, and localization to these compartments does not discriminate neurogenic tumors from other mediastinal tumors. In these compartments, including neurogenic tumors in the differential diagnosis must depend on other imaging characteristics.
Historically, in adults, the most common type of mediastinal tumor or cyst found is the neurogenic tumor (21%-usually in posterior mediastinum), followed by thymic tumors (19%-anterior mediaastinum), lymphomas (13%), and germ cell tumors (10%).
Only approximately one-third of the mediastinal tumors produce symptoms in adults.
On plain radiographs, schwannoma is usually sharply marginated, spherical and lobulated paraspinal mass.
On CT images, well circumscribed masses with low to intermediate attenuation which displace adjacent structures without direct invasion. Cystic and fatty degeneration are common. Small tumors typically demonstrate homogeneous enhancement. Large tumors may show heterogeneous enhancement. The larger a schwannoma, the more likely it is to show heterogeneity because of cystic degeneration or hemorrhage. Hemorrhage occurs in 5% of cases and calcification is rare.
On MR images, schwannoma shows isointense or hypointense signal intensity on T1-weighted images and intense enhancement on contrast-enhanced T1-weighted images. However, the enhancement may be heterogeneous because of cystic degeneration or hemorrhage. It shows heterogeneously hyperintense signal on T2-weight images. Cystic degenerative areas may be present, especially in larger tumors. Larger tumors often have areas of hemosiderin which can be detected on the T2* images.
Schwannomas are slow-growing lesions. Surgery is the treatment of choice. As schwannomas do not infiltrate the parent nerve, they can usually be separated from it. Recurrence is unusual, even after complete resection. They almost never undergo malignant change.
Please refer to: KSTR Imaging Conference 2016 Spring Case 1,
References: 1. Fujimoto K, Hara M, Tomiyama N, Kusumoto M, Sakai F, Fujii Y. Proposal for a new mediastinal compartment classification of transverse plane images according to the Japanese Association for Research on the Thymus (JART) General Rules for the Study of Mediastinal Tumors. Oncol Rep 2014; 31:565–572
Keywords: Mediatinum, Neurogenic tumor, Schwannoma ,

No. of Applicants : 60

▶ Correct Answer : 11/60, 18.3%

- Chonnam National University Hospital , Korea (South) SEUNGYOON CHAE
- The University of Tokyo Hospital , Japan MOTO NAKAYA
- university of montreal , Canada Andrei Bogdan Gorgos I
- Tiger Gate Hospital , Japan SHIN-ICHI CHO
- Ichinomiya Nishi Hospital , Japan Takao Kiguchi
- Fortis hospital , Mohali , India SHALEEN RANA
- Showa University Fujigaoka Hospital , Japan KYOKO NAGAI
- Vita Hospital , Brazil DIOGO LAGO PINHEIRO
- Other , Korea (South) MINSU KIM
- ZIGONG TCM HOSPITAL OF CHINA , China Cao Cunyou
- National Center for Global Health and Medicine , Japan HIROSHI TAKUMIDA

▶ Correct Answer as Differential Diagnosis : 17/60, 28.3%

- Diskapi Yildirim Beyazit Hospital, Ankara , Turkey MERIC TUZUN
- Holy Family Hopsital , India RAJESH GOTHI
- Hamamatsu University Hospital , Japan HAYATO NOZAWA
- Mayo Clinic , United States AKITOSHI INOUE
- , Japan YUMI MAEHARA
- CH de la Cote Basque , France PAUL ARDILOUZE
- University of Tsukuba, Dept of Radiology , Japan MANABU MINAMI
- Hamamatsu University Hospital , Japan YUKI HAYASHI
- Gifu University Hospital , Japan Yo Kaneko
- TWMU Medical Center East , Japan MASAFUMI KAIUME
- University of Tsukuba Hospital , Japan SODAI HOSHIAI
- Toranomon Hospital , Japan KAORU SUMIDA
- Private sector , Greece VASILIOS TZILAS
- Kinki University Faculty of Medicine, , Japan MITSURU MATSUKI
- Ajou University Hospital , Korea (South) HYERIN KIM
- Chonbuk National University Hospital , Korea (South) KUM JU CHAE
- McGill University Health Center , Canada Alexandre Semionov

대한흉부영상의학회 Korean Society of Thoracic Radiology

Archive of Old Cases

Case No : 1198 Date 2020-10-11

Discussion

No. of Applicants : 60