case_images: PMC9885797_01
case_images: Echocardiography imaging: (A) parasternal long axis section; (B) four-chamber section. An intracardiac echogenic mass (in the purple circles) 50 mm x 67 mm x 19 mm was visualized at the left atrioventricular junction outside the cardiac cavity. (C) Left ventriculography and myocardial contrast echocardiography showed an abundance of contrast agent filling into left ventricular and the mass.
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case_images: PMC9885797_01_fsurg-09-1036519-g001.jpg
case_images: F1
case_images: Left ventriculography and myocardial contrast echocardiography showed an abundance of contrast agent filling into left ventricular and the mass (Figure 1).
case_images: PET-CT imaging: (A) active FDG uptake of enlarged mediastinal multiple lymph nodes (SUVmax: 27.3) before treatment (in the blue circles); (B-D) active FDG uptake of the cardiac mass (SUVmax: 28.7) in the left atrium at the left AV junction (in the blue circles); (A-D) after treatment, the previous cardiac mass and enlarged mediastinal lymph nodes had disappeared completely (in the red circles).
case_images: fsurg-09-1036519-g002.jpg
case_images: PMC9885797_01_fsurg-09-1036519-g002.jpg
case_images: F2
case_images: Multiple enlarged mediastinal lymph nodes with active uptake of FDG (SUVmax: 27.3) were seen in neck IV and station 2L, 3a, 4, and 5 of the mediastinum, indicating metastasis (Figure 2). After 4 months of the treatment, the PCL and the enlarged mediastinal lymph nodes achieved complete remission as seen on the follow-up PET-CT after the treatment (Figure 2).
case_images: Pathological changes of specimen from the enlarged mediastinal lymph nodes. Medium-large heterotypic lymphoid cells showed diffuse and flaky hyperplasia. (A) (Hematoxylin and eosin stain,  100) the cells were round/oval; the cytoplasm was red stained; the nuclear chromatin was rough, and the mitotic figures were abundant. (B-E) (Immunohistochemical stain,  100) CD20 and CD79a high expression suggested B-cell origin. CD10 and BCL6 positive expression suggested the germinal center B-cell (GCB) type. (F) Fluorescence in situ hybridization (FISH) suggested EBER negative expression.
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case_images: PMC9885797_01_fsurg-09-1036519-g003.jpg
case_images: F3
case_images: These heterotypic cells were round/oval with red-stained cytoplasm and active mitosis (Figure 3A). Immunohistochemistry showed positive results for CD20 (+++), CD79a (+++), CD19 (+++), mum-1 90% (+), CD10 80% (+), bcl-2 95% (+), bcl-6 95% (+), c-myc 25% (+), p53 40% (+), and Ki67 80% (+), and negative results for CD3 (-), CD5 (-), CD21 (-), CD23 (-), CD30 (-), ALK (-), CyclinD1 (-), and CD38 (-), and PD-L1 (22C3) expression of 35% the tumor cells. (Figure 3B-E). The FISH results showed BCL6 (+), MYC (-), and BCL2/IGH (-), which ruled out double- and triple-hit high-grade B-cell lymphoma (Figure 3F).
case_images: Flow chart of the patient's clinical course: the patient's timeline of the onset of clinical symptoms, definitive diagnosis, treatment, and tumor response. CR, complete response.
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case_images: PMC9885797_01_fsurg-09-1036519-g004.jpg
case_images: F4
case_images: Figure 4. Further follow-up is required to ascertain the long-term outcome.