A 65 years old male was found to have hepatic cysts during physical examination more than 10 years ago. And the patient presented with epigastric pain and discomfort without obvious inducement half a year ago.
Then, he was admitted and underwent abdominal computed tomography (CT). The CT demonstrated multiple cystic space occupation of the liver and a 2.6 cm mass with prominent contrast enhancement at gastric body. It was suspected to be a (Gastrointestunal stromal tumors) GIST (Fig. 1A-D). Esophagogastroduodenoscopy revealed multiple gastric polyps and submucosal eminence of the gastric body (Fig. 1E).
Laboratory tests revealed an increase of platelet large cell ratio (P-LCR, 50.10%), mean platelet volume (MPV, 13.10 fL), platelet distribution width (PDW, 19.00 fL), uric acid (433.70 µmol/L), β2-microglobulin (3.50 mg/L), cystatin C (1.4mg/L) and decrease of total protein (63.30 g/L), serum complement C1q (143.90 mg/L). The tumor biomarkers such as neuron-specific enolase (NSE, 9.77 ng/ml), CA199 (37.26 U/ml) and CA50 (33.51 IU/ml) showed slightly higher.
Histopathological findings of the resected mass revealed a submucosal multinodular tumor measuring 1.9×1.4 cm. The tumor showed microscopically infiltrative growth into the smooth muscle bundles of the muscularispropria, some tumor cells were epithelioid and diffused in growth (Fig. 2A-C). There were loose myxoid and cellular areas of the tumor admixed with smooth muscle cells on high-powered microscopic fields (Fig. 2D). Immunohistochemical staining showed that the tumor cells were positive for smooth muscle actin (SMA), vimentin and H-caldesmon, but negative for Desmin, CD117, CD34, CK-20, Dog1, S100, Pan-CK, ER, PR, and CD10. In addition, CD34 highlighted a rich capillary network but was negative in tumor cells. The Ki-67 labeling index was less than 5% (Fig. 3). Besides, there was another growth pattern in this case. The tumor was characterised microscopically infiltrative growth into the smooth muscle bundles of the muscularis propria by diffusing on other tissue slice (Fig. 4A-C), no like the infiltrative growth pattern by multinodular and plexiform before, and the myxoid stroma was not that loose. Immunohistochemical staining showed that the tumor cells were positive for SMA ,vimentin and H-caldesmon but negative for Desmin, CD117, CD34, CK-20 Dog1, S100, Pan-CK, ER, PR, and CD10, just like the Fig. 2. In addition, CD34 highlighted a rich capillary network but was negative in tumor cells. The ki-67 labeling index was less than 5% (Fig. 5). In order to verify the real component of the tumor cells in the diffusing pattern, we used some molecular pathology methods. The GLI1 break-apart probe by FISH showed no positive finding in the tumor cells (Fig. 6A). No mutations were found in C-kit (exons 9, 11, 13,17) or PDGFRA (exons 12, 18) gene (Fig. 6B-C). The diagnostic process of this case in our department of pathology (Fig. 7). Under the HE staining by microscope, the morphology of the tumor cells and growth pattern looked like a GIST, PF or gastroblastoma. And the tumor cells were negative for Pan-CK and CD10 by immunohistochemistryl, we firstly excluded the diagnosis of gastroblastoma. Secondly, the tumor cells were negative for CD117, CD34 and Dog1 by immunohistochemistryl and were unmutated on C-kit or PDGFRA gene, we afterwards excluded the diagnosis of GIST. The last, according to the tumor cells were positive for SMA, vimentin and H-caldesmon and the negative for desmin, besides the GLI-1 disruption (-), we made the final diagnosis for PF. The final diagnosis was made by Dr. Xinyu Chen, Dr. Zhenyu Li, Dr. Qingming Jiang, and Dr. Dongfang Guo of the department of pathology in Chongqing University Cancer Hospital.
The patient remained under careful observation by endoscopy and CT follow-up, and there was no recurrence or metastasis in the 12 months follow-up. The patient got appropriate perspective including the assessment and the episode of care in every 3 months.