PMC7118410_01
Radiological examinations. A: Contrast-enhanced CT showing a large heterogenous mass shadow containing multiple cysts in the anterior mediastinum. B: There were no abnormal findings on the chest CT taken last year. C: PET-CT showing a low uptake only in the upper area of the mass. D: T2-weighed MRI showing high intensity areas predominantly consistent with multiple cysts.
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His chest X-ray showed a large mass shadow in the left hilum, and subsequent chest computed tomography (CT) revealed an anterior mediastinal tumor, with the largest diameter of 12 cm, containing multiple cysts (Fig. 1A). However, there were no abnormal findings on the follow-up chest CT of FMF performed in the previous year (Fig. 1B). Moreover, 18F-fluorodeoxyglucose-positron emission tomography/CT (PET/CT) showed low uptake of fluorodeoxyglucose (SUVmax = 3.6) in the mass, indicating a benign or low-grade malignant feature (Fig. 1C). Magnetic resonance imaging (MRI) demonstrated a huge mass with multiple cysts and solid components which suggested a mature teratoma (Fig. 1D).
T2-weighed MRI showing a homogenous high intensity mass (white arrow) in the patient's left testicle.
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During a preoperative systemic examination, a left testicular cyst was identified incidentally (Fig. 2).
Macroscopic findings. The mediastinal tumor, a solid and white colored mass, was resected completely with a part of the left lung (white arrow) and thymus (yellow arrow). (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)
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Eventually, we performed a complete resection of the left testicular cyst and the mediastinal tumor, included a part of the left lung that was adhered to the mediastinal tumor (Fig. 3).
Pathological findings. Histopathological analysis showing multiple areas of mature epidermis with respiratory epithelium (A), sebaceous glands (B), and parathyroid glands (C) in the mediastinal mass.
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Microscopically, the tumor consisted of several cysts, which were lined by mature epithelium, containing sebaceous glands, nests of respiratory epithelium, cartilage, and parathyroid glands (Fig. 4A, B and C).