Abstract
BACKGROUND: Histiocytic sarcoma (HS) is a rare hematologic neoplasm with a few hundred cases having been described to date. CASE PRESENTATION: We report the case of a 56-year-old woman with a history of hepatitis C infection and chronic kidney disease (CKD), submitted to a kidney transplant in 1984, under maintenance immunosuppression with prednisone and azathioprine. Patient presented with a relentlessly growing mass on her right front thorax. It was painless, smooth, and adherent to the deep muscle. Laboratory studies were unremarkable. Ultrasonography and computerized tomography (CT) scan revealed a highly vascularized heterogeneous mass (8×9 cm), with a necrotic centre. Positron emission tomography (PET) scan demonstrated multiple thoracic, abdominal, and pelvic nodules. Histology revealed a highly undifferentiated HS (vimentin, CD68, CD99, and CD4 positive). In spite of having started treatment with etoposide and thalidomide, no clinical response was achieved and the patient died three months later. CONCLUSIONS: To the authors' knowledge, this is the first described case of HS in a solid organ transplant patient.