A 27-year-old Chinese woman presented with menstrual volume increase for three years and vaginal bleeding for 24 days. The patient explained that the menstrual volume was about twice that before she became aware of something amiss. Enhanced arterial phase CT showed that the volume of the uterus significantly increased, and space-occupying lesions could be seen in the uterus with a size of about 9.5 cm × 8.5 cm × 8 cm. A mass with a mixed density shadow was observed in the uterus, and the boundary was unclear (Fig. 1-①). Resected specimens were sent to the Department of Pathology for examination. There was a large mass in the uterine cavity at a size of 9 cm × 8 cm × 8 cm; the section was grey white and grey red. The bilateral ovaries and oviduct were not involved by SDUS (Fig. 1-②).
Haematoxylin and eosin staining was performed on suspected SDUS samples. Microscopically, the tumour cells were diffusely distributed, displaying flake or acinar shapes. SDUS tumour cells in some areas had lost adhesion, and some SDUS tumour tissues grew around and invaded the blood vessels (Fig. 1-A). Extensive necrosis was observed (Fig. 1-B). Vascular and normal endometrial gland invasion was observed (Fig. 1-C). The tumour cells were epithelioid and had eosinophilic cytoplasm, and some cells showed nuclear deviation towards the cytoplasm. These cells were rhabdoid with round or oval nuclei (Fig. 1-D). The results of immunohistochemistry of the Ki-67 proliferation marker showed a high percentage (60%) of cell staining, with the expression of INI-1, the local expression of CD10, and the lack of expression of BRG1, CK (Pan), SYN, Desmin, and ER (Fig. 1).
The NGS was conducted at Geneseeq Technology Inc. (Nanjing, China). Formalin-fixed paraffin-embedded sections of the uterine tumour were subjected to comprehensive NGS analysis with 425 predefined related genes. Data were sequentially analysed by an effective bioinformatics process. Germline mutations were filtered out by comparing to patient’s whole blood controls. In our case, the genetic analysis result showed that no germline mutation was detected in her family. A SMARCA4 splicing mutation, c.355 + 190_616del, was detected at a MAF of 86.4% in the tumour sample, accompanied by a SMARCA4 frameshift mutation p.H571Gfs (45.8%). TMB: 1.1 mutations/MB. Our NGS test includes MMR, MSI, PTEN, PIK3CA, TP53, beta-catenin, etc. Our NGS test report showed SMARCB1, CTNNBI, MMR, MSI, PTEN, PIK3CA, TP53 were negative. In conclusion, a clinical diagnosis of SDUS was confirmed by expert consultation (Fig. 2).
The Multiple Immunofluorescent Staining was conducted at Genecast Biotechnology Co. Ltd. (Beijing, China). The results showed that there were some infiltrating immune cells expressing CD8(+,0.92%) and CD68(+,0.2%) in SDUS tissues. A few cells expressing PD-1(+,0.06%) and PD-L1(+,0.06%) were detected by immunofluorescence (Fig. 2). The results of immunohistochemical staining showed that some of the immune cells expressing CD3 and CD8 had infiltrated into SDUS tissues, but no PD-L1 expression was detected (Fig. 2). Approximately 27 T-cells per high power field (HPF) had infiltrated into SDUS tissues. The results showed that SDUS had immunogenicity.
In our case, the tumour stage was pt3bnxmx. the patient underwent hysterectomy and bilateral salpingo-oophorectomy, then received gemcitabine and docetaxel chemotherapy for 4 cycles. After PET-CT examination, it was found that there were hypermetabolic signals in the left iliac fossa and pelvic cavity of the patient, suggesting that the tumour had a trend of further deterioration (Fig. 3). The treatment plan was changed to epirubicin and ifosfamide chemotherapy. During 3 cycles of treatment, the patient experienced serious side effects and the patient eventually gave up on chemotherapy. The patient is still alive and displayed the left iliac fossa lesion enlargement in the 6-month follow-up check.