A 15-year-old girl was admitted to our hospital due to intermittent chest pain occurring for more than 2 months and cough and wheezing for 10 days. The patient was a student, and her family denied a history of malignancy. Chest examination revealed solid sounds obtained during percussion and low breath sounds over the left thorax.
The laboratory tests showed increased procalcitonin (26.59 ng/ml), elevated interleukin-6 (15.2 pg/ml), and a slightly high erythrocyte sedimentation rate of 28 mm/h. The patient underwent transcatheter thoracic drainage to determine the features of the pleural effusion, and a routine examination showed bloody turbid pleural effusion without tumor cells (Figure 1). However, the levels of carcinoembryonic antigen and lactic dehydrogenase in the pleural effusion were more than three times the normal upper limit. Acid-fast staining and tuberculosis gene sequencing of the pleural effusion were normal, helping us rule out the possibility of tuberculous pleural effusion.
A chest computed tomography (CT) scan showed a large soft tissue mass (15.7 x 11.7 x 10.5 cm) near the left mediastinum with multiple nodules and masses in the left pleura, and the fluid could be seen on the same side of the thorax (Figure 2a and b). Moderately heterogeneous enhancement with multiple small vessel shadows could be seen in the aforementioned mass and nodules after the injection of a contrast agent (Figure 2a and b). A radiological examination of the abdomen and brain revealed no other lesions.
A percutaneous puncture biopsy was performed to clarify the properties of this mass. Pathological examination showed a population of small, round, deeply stained tumor cells. The tumor cells formed clusters. Immunohistochemical results demonstrated strong positivity for CD99, FLI-1, and NKX2, which are the markers of EES. The cells were also positive for Ki-67 (approximately 30%). The tumor cells were negative for MPO, GFAP, CD30, EMA, CgA, desmin, and WT-1 (Figure 3). The negativity for these markers excluded lymphoma and glioma. After discussion by a multidisciplinary treatment (MDT) team, the mass was initially identified as ES derived from the mediastinum. Fluorescence in situ hybridization (FISH) suggested EWSR1 gene breakage and rearrangement (Figure 4). Based on the aforementioned results, the patient was diagnosed with left mediastinum ES with pleural effusion.
Considering the age, tumor size and properties, and the consensus from the MDT meeting, the patient received treatment with cyclophosphamide (1.8 g), adriamycin (doxorubicin) (75 mg), and vincristine (2 mg) (VDC) for the first cycle. After finishing one cycle of chemotherapy, a CT scan of the chest revealed that the tumor was approximately half its size before treatment, and the pleural effusion had decreased (Figure 2c and d). After approximately 3 weeks, the patient received cyclophosphamide (1.6 g), adriamycin (doxorubicin) (67.5 mg), and vincristine (1.8 mg) for the second cycle. After six cycles of treatment, the tumor was hard to observe, and no pleural effusion was observed (Figure 2e and f). The patient felt no chest pain and did not cough or wheeze. For the ongoing treatment plan, a regular chemotherapy will be continued, and the patient is advised to follow up.