2730 Unexpected Cause of Globus Pharyngeous: Gastric Leiomyosarcoma

Abstract

INTRODUCTION: Soft tissue sarcomas (STS) are derived from smooth muscle cells and typically arise in adipose tissue, blood vessels or structural tissue surrounding the organs of the body. One of the most common types of STS is leiomyosarcoma (LMS) which account for 11% of all sarcomas diagnosed. Gastric LMS are exceptionally rare and make up 0.1% of all mesenchymal tumors of the stomach. CASE DESCRIPTION/METHODS: A 72 year-old male presented to the gastroenterology clinic with complains of globus pharyngeus, migrating abdominal discomfort and a 4-month 18 pound weight loss. Endoscopy revealed a large bloody friable mass in the posterior wall of the stomach. Biopsy demonstrated atypical spindle cell proliferation. Immunohistochemistry was positive for Smooth Muscle Actin (SMA), desmin and CD34; cKIT and DOG1 was negative. He was diagnosed with high grade LMS of the stomach with no metastasis after unremarkable positron emission tomography scan. The patient underwent total gastrectomy with splenectomy en-bloc resection to achieve wide negative margins. DISCUSSION: This case highlights an unexpected cause of globus pahryngeus: Gastric LMS which is important to differentiate from gastrointestinal stromal tumor (GIST) as its management and prognosis differ. LMS represent 0.1% of all gastric tumors, and 3% of all gastrointestinal malignancies. In contrast, GIST has annual incidence of 11-14.5 per million population. LMS and GIST appear similar on gross assessment and clinical symptoms and need to be differentiated via immunohistochemical staining. LMS are actin and desmin reactive with DOG1.1 typically being absent. Further, LMS lack cKIT and PDGFRα mutations that are seen in GIST. Management of GIST with tyrosine kinase is potentially lifesaving, whereas no such treatment exists for LMS where the cornerstone of treatment is surgery. Chemotherapy and radiation have been shown to be only helpful for palliative measures. They are intrinsically aggressive tumors and 90% are moderate to high grade at time of diagnosis with evidence of metastatic disease. We are far from understanding the pathology of LMS and its risk factors. This case confirms our present understanding of LMS; as shown by positive markers as well a diagnosis of high grade tumor on presentation. However, it also challenges our current understanding of LMS in its unusual symptomatology and lack of metastatic disease. Due to its low incidence, it is crucial to report cases such as this in order to further our understanding of the tumor.