case_images: PMC10904483_01
case_images: (A) Chest plain CT scan showing a mass with an irregularly round shape (blue arrow) that compressed the adjacent structure (red arrow) in the superior mediastinum, including the trachea and vessels. (B) Contrast-enhanced chest CT scan showing that the enhancement of the lesion was uneven and obvious (blue arrow), with a compressed and irregularly narrow superior vena cava (red arrow). (C, D) Coronal and sagittal reconstruction showing the position of the cystic and solid mass (blue arrow) in the superior mediastinum. (E, F) After a four-month course of combined chemotherapy, the chest CT scan and contrast-enhanced chest CT scan showed shrinkage of the mass and decreased compression of surrounding structures, such as the trachea (red arrow). (G, H) Coronal and sagittal reconstruction also showing a reduction in the mass volume and a decrease in the solid component (blue arrow), accompanied by pleural effusion (red arrow). (I, J) CT scan two months after surgery showing hydropneumothorax in the thoracic cavity (blue arrow). (K, L) CT scan two months after surgery showing encapsulating cystic fluid accumulation near the surgical area (blue arrow).
case_images: fonc-14-1288213-g001.jpg
case_images: PMC10904483_01_fonc-14-1288213-g001.jpg
case_images: f1
case_images: A plain chest CT at the outpatient clinic revealed a round soft tissue mass that compressed the trachea toward the left, leading to a diagnosis of neoplasm in the right neck extending to the mediastinum ( Figure 1A ). The mass had clear borders and uneven density with patchy areas of low density, which is characterized by marked and heterogeneous enhancement ( Figures 1B, D ). Additionally, adjacent blood vessels exhibited indistinct boundaries due to invasion, particularly the irregular narrowing of the invaded superior vena cava ( Figures 1B, C ). After five courses of combined therapy, contrast-enhanced CT showed that the mass had shrunk to a size of 7.5x3.2x6.9 cm with the presence of pleural effusion, accompanied by a decrease in its solid component and reduced compression of surrounding structures ( Figures 1E, G, H ). CT imaging still showed uneven and significant enhancement of the mass ( Figures 1F- H ). Complex mediastinal tumor resection was performed when the condition of the tumor was eligible for surgical indications. Subsequently, a CT scan performed two months after surgery revealed the chest condition post-operation: slight atelectasis of the right lung with hydropneumothorax in the thoracic cavity ( Figures 1I-L ).
case_images: (A) Histopathology image showing tumor cells composed of malignant short spindle cells (H&E staining). (B) Immunohistochemistry image showing positivity for CD99. (C) FISH results showing that the proportion of SS18 (18Q11) SYT:1R1G1F signal type abnormal cells was 24%, and the SYT gene was broken. The FISH results were positive.
case_images: fonc-14-1288213-g002.jpg
case_images: PMC10904483_01_fonc-14-1288213-g002.jpg
case_images: f2
case_images: Subsequently, the histopathologic examination of the mass indicated a number of malignant short spindle cells ( Figure 2A ), while the immunohistochemistry results showed that the cells were positive for CD99 ( Figure 2B ), Bcl-2 and calponin but negative for AE1/AE3, EMA, NKX2.2, and WT1, while Ki-67 was 40%. Meanwhile, the result of fluorescence in situ hybridization (FISH) was positive ( Figure 2C ), which revealed translocation of t (18q 11.2) (SS18), and the SYT gene was broken.