PMC10014623_01
Chest x-ray. (A) Large soft tissue shadow in bilateral thoracic cavity. (B) Chest x-ray 2 months after thymectomy showed good expansion of both lungs and no recurrence.
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F1
Chest radiographs showed large soft tissue shadows in the bilateral thoracic cavity (Figure 1A). No recurrence was detected on chest x-ray and both lungs were well dilated (Figure 1B).
Enhanced computed tomography. (A) The mediastinal window shows a solid low-density soft tissue mass in the mediastinum and bilateral thoracic cavity with mild homogeneous enhancement, and the adjacent lung tissue is displaced by compression, but no involvement is seen. (B) The lung windows showed a decrease in volume of both lungs with no significant abnormal density shadow. (C,D) Bilateral soft tissue masses in the thorax were seen in the coronal and sagittal planes, growing around the heart shadow, clearly demarcated from the lung tissue, and no obvious involvement was seen.
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F2
Enhanced computed tomography scan of the chest revealed that the thymus was significantly enlarged, it had smooth margins, regular morphology, and mild uniform enhancement, both lungs were compressed, solid, and non-distended, and the distal segments of the left and right main bronchi and their branches were thinned, and the superior vena cava, right subclavian vein, and left cephalic brachial vein were thickened, which was considered as thymic hyperplasia (Figures 2A-D).
Intraoperative exploration. (A) Thoracoscopic exploration revealed a large mass from the mediastinum filling most of the bilateral thoracic cavity, squeezing both lungs backwards and upwards and compressing the pericardium. (B) The thymus wraps and compresses mediastinal structures (superior vena cava, left cephalic brachial vein, etc.), but does not attach to or invade mediastinal structures and can be easily dissected free. (C) Left lobe thymus was exposed during the surgery. (D) Part of the left lobe thymus was preserved.
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F3
It had an intact envelope, a yellowish-white solid lobulated shape, and a soft texture, and these were consistent with the normal thymus appearance (Figure 3A). It compressed but did not invade the surrounding structures and measured approximately 12 x 10 x 5 cm (Figure 3B), with the phrenic nerve traveling at its margin. We used an electric scalpel to first free dissect and removed the mass occupying the right side of the thorax in its entirety, followed by freeing and removing most of the mass occupying the left side of the thorax, preserving part of the thymus in the left lobe and the volume of the preserved thymus is about 1/3 of the normal unilateral thymus in the age cohorts (Figures 3C,D).
Pathological specimens and microscopic findings. (A) Crushed lumpy tissue with soft, homogeneous, oily feel of ash powder in the profile. (B) Postoperative pathological examination showed enlarged lobular structures with clear corticomedullary demarcation and visible thymic vesicles (H&E, 5x).
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F4
Finally, we enlarged one of the trocar holes to 2 cm and removed the tissue using a retrieval bag, and the weight of the resected mass was approximately 308 g (Figure 4A). Combined with the immunohistochemical staining results, it was considered consistent with true thymic hyperplasia (Figure 4B).