NF1 mutation and TUBB3 amplification in gastric histiocytic sarcoma: a case report and literature review.

Abstract

Histiocytic sarcoma is a rare neoplasm of mature histiocytes with an aggressive clinical courseandpoor response to treatment. Primary gastric histiocytic sarcomais rarerand just reported sporadically.Histiocytic sarcoma is a rare neoplasm of mature histiocytes with an aggressive clinical courseandpoor response to treatment. Primary gastric histiocytic sarcomais rarerand just reported sporadically. A case of a 71-year-old female admitted with a one-year history of upper abdominal pain exacerbated after meals. After CT scans revealed a bulged mass atthe lesser curvature of the gastric body, the patient underwent endoscopic submucosal dissection. Microscopically, non-cohesive neoplastic cells diffuselyinfiltrated lamina propria and submucosa, and diffusely expressed LCA, CD4, CD163, CD68 (KP1),CyclinD1, Lysozyme, and Vimentin. PD-L1 (22CS) expression evaluated as CPS 60. The final pathological diagnosis was gastric histiocytic sarcoma.Subsequently, next-generation sequencing identified a nonsense mutation in exon 21 ofNF1gene [c.2446C > T (p.R816*)]andtheTUBB3gene amplification (copy number: 4.55).The patient refused further treatment and died of the tumorhalf a year later. This case broadens the spectrum of differential diagnosis of gastric cancerand emphasizes the value of immunohistochemicaland molecular testsin the accurate diagnosis of histiocytic sarcoma. Furthermore, we performed literature review of 11 cases of gastric histiocytic sarcoma so as to strengthen the understanding of the clinicopathologic features, treatment, and prognosis.