title: Histiocytic sarcoma; case report of a rare disease in a kidney transplant recipient.
abstract: BACKGROUND
  Histiocytic sarcoma (HS) is a rare hematologic neoplasm with a few hundred cases having been described to date.
  
  
  METHODS
  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.
authors: Renal Transplant Unit, Nephrology Department, Centro Hospitalar do Porto, Portugal.
authors: Pedro
authors: P
authors: Ventura Aguiar
authors: Department of Pathology, Centro Hospitalar do Porto, Portugal.
authors: Carla
authors: C
authors: Dias
authors: Renal Transplant Unit, Nephrology Department, Centro Hospitalar do Porto, Portugal.
authors: Pedro
authors: P
authors: Azevedo
authors: Renal Transplant Unit, Nephrology Department, Centro Hospitalar do Porto, Portugal.
authors: Hugo Neves
authors: HN
authors: Silva
authors: Renal Transplant Unit, Nephrology Department, Centro Hospitalar do Porto, Portugal.
authors: Manuela
authors: M
authors: Almeida
authors: Renal Transplant Unit, Nephrology Department, Centro Hospitalar do Porto, Portugal.
authors: Sofia
authors: S
authors: Pedroso
authors: Renal Transplant Unit, Nephrology Department, Centro Hospitalar do Porto, Portugal.
authors: La Salete
authors: LS
authors: Martins
authors: Renal Transplant Unit, Nephrology Department, Centro Hospitalar do Porto, Portugal.
authors: Leonídio
authors: L
authors: Dias
authors: Renal Transplant Unit, Nephrology Department, Centro Hospitalar do Porto, Portugal.
authors: Anabela
authors: A
authors: Rodrigues
authors: Department of Pathology, Centro Hospitalar do Porto, Portugal.
authors: Ramón
authors: R
authors: Viscaíño
authors: Renal Transplant Unit, Nephrology Department, Centro Hospitalar do Porto, Portugal.
authors: António
authors: A
authors: Cabrita
authors: Renal Transplant Unit, Nephrology Department, Centro Hospitalar do Porto, Portugal.
authors: António Castro
authors: AC
authors: Henriques
keywords: Chronic kidney disease; Histiocytic sarcoma; Malignancy; Post-transplant lymphoproliferative disease; Transplant