Plexiform Angiomyxoid Myofibroblastic Tumor of the Stomach

Endoscopic submucosal excavation for gastric plexiform fibromyxoma: A case report and systematic review of literature

Plexiform fibromyxoma (PF) is a rare mesenchymal tumor of which the pathogenesis and molecular changes are still unclear. Histologically, it is characterized by a cluster of bland spindle or ovoid cells growing in the mucoid or fibromyxoid stroma rich in small blood vessels. At present, surgical resection is the primary treatment for PF.

Huge gastric plexiform fibromyxoma presenting as pyemia by rupture of tumor: A case report

BACKGROUND

Plexiform fibromyxoma (PF) is a rare mesenchymal tumor, with limited case reports worldwide. Common clinical symptoms are abdominal discomfort and bleeding signs, which frequently present slow-onset in reported cases. Herein, we report a case of gastric PF presenting as acute onset and with pyemia accom-panying tumor rupture. We resected the tumor as well as the distal gastric, bulbus duodeni and gallbladder for treatment in emergency surgery. Notably, before the onset of the disease, the patient received coronavirus disease 2019 (COVID-19) vaccines.

CASE SUMMARY

A 26-year-old man was admitted to our hospital, due to abdominal pain and fever after having received COVID-19 vaccines. Laboratory examination indicated severe sepsis. Computed tomography scan revealed a large mass in the abdomen. Deformation of the gastrointestinal tract was seen during gastroscopy. After failure of anti-infective treatment and symptoms of shock developed, he received an emergency surgery. We found a huge and partly ruptured mass, with thick purulence. Microscopically, the mass was composed of spindle cells with clarified cytoplasm, accompanied by myxoid stroma and arborizing blood vessels. Immunohistochemistry showed the tumor cells as positive for smooth muscle actin and succinate dehydrogenase subunit B but negative for DOG-1 and CD117. Finally, the patient was diagnosed with gastric PF and discharged from the hospital.

CONCLUSION

Gastric PF manifesting as tumor rupture combined with pyemia is rare. Timely surgery is critical for optimal prognosis.

Plexiform angiomyxoid myofibroblastic tumor treated by endoscopic submucosal dissection: A case report and review of the literature

BACKGROUND

Plexiform angiomyxoid myofibroblastic tumor (PAMT) is a rare mesenchymal tumor characterized by multiple nodular plexiform growth patterns and an immunophenotype with myofibroblasts. The pathological characteristics, immunohistochemistry, diagnostic criteria, differential diagnosis, and gene-level changes of PAMT have been reported in many studies. At present, the main treatment for PAMT in the reported cases is surgery; only eight cases were treated via endoscopy (excluding 1 thoracoscopic resection), and the lesions were all smaller than 5 cm. There are no reports on the prognosis and follow-up of young patients with lesion sizes reaching 5 cm who undergo endoscopic submucosal dissection (ESD). Herein, we present the first case of a young patient with a lesion size reaching 5 cm who was diagnosed with PAMT via endoscopic submucosal dissection.

CASE SUMMARY

A 15-year-old young man with upper abdominal pain for 2 years presented to the Gastroenterology Department of our hospital. Painless gastroscopy showed a semicircular bulge approximately 5 cm in size in the lesser curvature near the cardia of the fundus; the surface was eroded, and shallow ulcers had formed. The pathological manifestations of the biopsy were spindle cell proliferative lesions with interstitial mucinous changes, and the surface mucosa showed chronic inflammatory changes with active lesions; immunohistochemistry showed smooth muscle actin (SMA) (+), CD117 (-), CD34 (-), DOG-1 (-), S-100 (-), and Ki67 (LI: < 1%). We performed ESD on the patient. The lesion that we removed was 5 cm × 4 cm × 2 cm in size. Pathologically, the resected tissue displayed typical manifestations, such as fat spindle-shaped fibroblasts and myofibroblast-like cells showing irregular nodular hyperplasia. Immunohistochemistry staining of the tumor cells revealed the following: CD34 (partially +), SMA (weakly +), CD117 (-), DOG-1 (-), S-100 (-), SDHB (+), PCK (-), and Ki67 (labelling index: 2%). There was no recurrence or metastasis during the 3-mo follow-up after the operation, and the treatment effect was good. We also performed a review of the literature on the clinical manifestations, pathological features, immunohistochemistry, and differential diagnosis of PAMT.

CONCLUSION

At present, the diagnostic criteria for PAMT are relatively clear, but the pathogenesis and genetic changes require further study. PAMT is benign in nature, and these patients are less likely to experience local or metastatic recurrence. The main treatment is still surgery if the lesion is in the stomach. Partial gastrectomy and distal gastrectomy are the most frequently performed surgical treatments for PAMT, followed by local resection, subtotal gastrectomy, and wedge resection. But for comprehensive evaluation of the disease, ESD can be considered a suitable method to avoid excessive treatment.