RESUMEN
Histiocytic sarcoma (HS) is a rare malignant neoplasm of the lymphohematopoietic system, that occurs in lymph nodes, skin and at extranodal sites, particularly the gastrointestinal tract. Although it shows characteristics histoiogical and immunohistochemical features, it may be misdiagnosed. We report a 67 year-old female patient presenting with colicky abdominal pain and vomiting. A CT sean of the abdomen revealed a tumor in the ileum, that was surgically removed. On pathology, the neoplastic cells displayed large abundant eosinophilic cytoplasm, with bizarre-shaped nuclei, that expressed CD 45, CD 68 and lisozyme. The diagnosis of HS requires the use of a panel of immunohistochemical markers and may be supported by ultrastructural findings .