Small bowel and lung histiocytic sarcoma revealed by acute peritonitis: A case report with review of literature.

Introduction And Importance: Histiocytic sarcoma (HS) is a rare malignant neoplasm showing morphologic and immunohistochemical features of histiocytes. It is characterized typically by extranodal presentation and a poor clinical course, particularly in cases with disseminated disease.

Case Presentation: This report documents a case of bifocal and aggressive HS in small bowel and lung revealed by acute peritonitis in a 63-year-old man.

Clinical Discussion: Despite its rarity, we believe that the correct diagnosis of HS is crucial for clinical treatment and prognostic prediction.

Conclusion: The collection of additional cases of HS are important to obtain further progress in prognosis and guide treatment decisions.