[A case of extranodal histiocytic sarcoma of stomach mimicking gastric adenocarcinoma]

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

Histiocytic sarcoma is a rare neoplasm of mature histiocytes with an aggressive clinical course and poor response to treatment. Primary gastric histiocytic sarcoma is rarer and just reported sporadically.Histiocytic sarcoma is a rare neoplasm of mature histiocytes with an aggressive clinical course and poor response to treatment. Primary gastric histiocytic sarcoma is rarer and 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 at the lesser curvature of the gastric body, the patient underwent endoscopic submucosal dissection. Microscopically, non-cohesive neoplastic cells diffusely infiltrated lamina propria and submucosa, and diffusely expressed LCA, CD4, CD163, CD68 (KP1), Cyclin D1, 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 of NF1 gene [c.2446C > T (p.R816*)] and the TUBB3 gene amplification (copy number: 4.55). The patient refused further treatment and died of the tumor half a year later. This case broadens the spectrum of differential diagnosis of gastric cancer and emphasizes the value of immunohistochemical and molecular tests in 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.

Primary histiocytic sarcoma of the stomach: A case report with imaging findings

Histiocytic sarcoma (HS) is a rare malignant neoplasm that originates from a histiocytic hematopoietic lineage characterized by histiocytic differentiation and its corresponding immunophenotypic features. We herein reported a case of primary HS of the stomach which was confirmed through histopathologic examination and immunohistochemical staining. A 52-year-old woman presented with progressive difficulty in feeding and dull pain in the epigastric region. Gastroscopy, endoscopic ultrasonography, double contrast examination, and computed tomography revealed a mass located on the posterior wall of fundus and lesser curvature of the stomach. Microscopically, the cytoplasm of the tumor cells was abundant and eosinophilic. Immunohistochemical staining revealed that the tumor cells were positive for CD45RO and CD68. It is difficult to differentiate HS of stomach from other gastric malignancies by radiological evaluation alone. However, HS may be considered when a protruding and ulcerated mass in stomach shows heterogeneous hypervascular features. To the best of our knowledge, this is the first report in English language literature that emphasizes the imaging findings of human gastric HS.