Gastric plexiform fibromyxoma, an uncommon mesenchymal tumor

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 fibromyxoma: a clinicopathological and immunohistochemical analysis of two cases with a literature review

OBJECTIVE

This article aimed to study the clinicopathological features, immunophenotypes, and differential diagnoses of plexiform fibromyxoma (PF).

METHODS

We searched clinical and pathology databases of our hospital for patients with histologically confirmed PF from 2007 to 2020 and reviewed the relevant English and Chinese language literature.

RESULTS

Two cases of PF were identified, a 67-year-old woman and a 23-year-old man. Both patients presented with melena and anemia and underwent partial gastrectomy. Histologically, the tumors exhibited a plexiform growth pattern in the gastric submucosa and the presence of bland-looking spindle cells in the fibromyxoid stroma with the formation of small blood vessels. Immunohistochemically, the two cases were strongly positive for vimentin, smooth muscle actin, and muscle-specific actin and negative for CD117, discovered on gastrointestinal stromal tumors protein 1, CD34, CD10, S100, desmin, H-caldesmon, estrogen receptor, progesterone receptor, β-catenin, and cytokeratin.

CONCLUSIONS

PF is a rare mesenchymal tumor of the stomach that can be distinguished from other gastrointestinal mesenchymal tumors based on its distinctive morphology and immunophenotype.

Plexiform fibromyxoma: Review of rare mesenchymal gastric neoplasm and its differential diagnosis

Plexiform fibromyxoma (PF) is a very rare mesenchymal neoplasm of the stomach that was first described in 2007 and was officially recognized as a subtype of gastric mesenchymal neoplasm by World Health Organization (WHO) in 2010. Histologically, PF is characterized by a plexiform growth of bland spindle to ovoid cells embedded in a myxoid stroma that is rich in small vessels. The lesion is usually paucicellular. While mucosal and vascular invasion have been documented, no metastasis or malignant transformation has been reported. Its pathogenesis is largely unknown and defining molecular alterations are not currently available. There are other mesenchymal tumors arising in the gastrointestinal tract that need to be differentiated from PF given their differing biologic behaviors and malignant potential. Histologic mimics with spindle cells include gastrointestinal stromal tumor, smooth muscle tumor, and nerve sheath tumor. Histologic mimics with myxoid stroma include myxoma and aggressive angiomyxoma. Molecular alterations that have been described in a subset of PF may be seen in gastroblastoma and malignant epithelioid tumor with glioma-associated oncogene homologue 1 (GLI1) rearrangement. The recent increase in publications on PF reflects growing recognition of this entity with expansion of clinical and pathologic findings in these cases. Herein we provide a review of PF in comparison to other mesenchymal tumors with histologic and molecular resemblance to raise the awareness of this enigmatic neoplasm. Also, we highlight the challenges pathologists face when the sample is small, or such rare entity is encountered intraoperatively.