Intrathymic cyst: clinical and radiological features in surgically resected cases.
OBJECTIVE
To investigate radiological and clinical characteristics of pathologically proven cases of intrathymic cysts.


METHODS
The study population consisted of 18 patients (five males, 13 females; median age 56 years) with pathologically confirmed intrathymic cysts who underwent thymectomy and had preoperative chest computed tomography (CT) available for review. The patient demographics, clinical presentation, and preoperative radiological diagnoses were reviewed. CT images were evaluated for shape, contour, location of the cysts and the presence of adjacent thymic tissue, mass effect, calcifications, and septa. The size and CT attenuations of the cysts were measured.


RESULTS
The most common CT features of intrathymic cysts included oval shape (9/18; 50%), smooth contour (12/18; 67%), midline location (11/18; 61%), the absence of visible adjacent thymic tissue (12/18; 67%), and the absence of calcification (16/18; 89%). The mean longest diameter and the longest perpendicular diameter were 25 mm (range 17-49 mm) and 19 mm (range 10-44 mm), respectively. The mean CT attenuation was 38 HU (range 6-62 HU) on contrast-enhanced CT, and was 45 HU (range 26-64 HU) on unenhanced CT (p = 0.41). The CT attenuation was >20 HU in 15 of 18 patients (83%). Preoperative radiological diagnosis included thymoma in 11 patients.


CONCLUSIONS
In surgically removed, pathologically proven cases of intrathymic cyst, the CT attenuation was >20 HU in most cases, leading to the preoperative diagnosis of thymoma. Awareness of the spectrum of imaging findings of the entity is essential to improve the diagnostic accuracy and patient management.
Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, 75 Francis St., Boston, MA, USA.
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T
Araki
Department of Pathology, Brigham and Women's Hospital, 75 Francis St., Boston, MA, USA.
L M
LM
Sholl
Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, 75 Francis St., Boston, MA, USA.
V H
VH
Gerbaudo
Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, 75 Francis St., Boston, MA, USA.
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H
Hatabu
Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, 75 Francis St., Boston, MA, USA; Department of Imaging, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA. Electronic address: Mizuki_Nishino@DFCI.HARVARD.EDU.
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Nishino
D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008476:Mediastinal Cyst / Q000473:pathology* / Q000601:surgery; D008875:Middle Aged; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D013945:Thymoma / Q000473:pathology; D013953:Thymus Neoplasms / Q000473:pathology; D014057:Tomography, X-Ray Computed