title: Renal malignant solitary fibrous tumor with single lymph node involvement: report of unusual metastasis and review of the literature.
abstract: Solitary fibrous tumors are rare mesenchymal spindle cell neoplasms that are usually found in the pleura. The kidneys are an uncommon site and only few cases of renal solitary fibrous tumor exhibit malignant behavior metastasizing to the liver, lung, and bone through the hematogenous pathway.
  
  
  OBJECTIVE
  To describe the first case of lymph node metastasis from renal solitary fibrous tumor in order to increase the knowledge about the malignant behavior of these tumors.
  
  
  METHODS
  A 19-year-old female patient had intermittent hematuria for several months without flank pain or other symptoms. A chest and abdomen CT scan was performed and showed a multi-lobed bulky solid mass of 170 × 98 × 120 mm in the left kidney. One day before the surgery, the left renal artery was catheterized and the kidney embolization was performed using a Haemostatic Absorbable Gelatin Sponge and polyvinyl alcohol. We then performed a radical nephrectomy with hilar, para-aortic, and inter-aortocaval lymphadenectomy.
  
  
  RESULTS
  Estimated intraoperative blood loss was 200 mL and the operative time was 100 minutes. No postoperative complications occurred. The hospital stay was 7 days long. The histological examination was malignant solitary fibrous tumor of the kidney. Cancerous tissue showed cellular atypia, with an increased mitotic index (up to 7 × 10 hpf). Immunohistochemical analysis showed positive results for CD34, BCL2, partial expression of HBME1, and occasionally of synaptophysin. Histological evaluation confirmed the presence of metastasis in one hilar node. The patient did not receive any other therapy. At 30-month follow-up, the patient was in good health and no local recurrence or metastases had occurred.
  
  
  CONCLUSIONS
  This is the first case of lymph node metastasis from a renal solitary fibrous tumor showing unusual malignant behavior; this finding adds new information about the biology and progression of these tumors, which remain unclear.
authors.affiliation: Department of Medical-Surgical Specialties and Public Health, Division of Urological Andrological Surgery and Minimally Invasive Techniques, University of Perugia, Terni, Italy.
authors.forename: Ettore
authors.initials: E
authors.lastname: Mearini
authors.affiliation: Department of Medical-Surgical Specialties and Public Health, Division of Urological Andrological Surgery and Minimally Invasive Techniques, University of Perugia, Terni, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Cochetti
authors.affiliation: Department of Medical-Surgical Specialties and Public Health, Division of Urological Andrological Surgery and Minimally Invasive Techniques, University of Perugia, Terni, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Barillaro
authors.affiliation: Medical Oncology, S Maria Hospital, Terni, Italy.
authors.forename: Sonia
authors.initials: S
authors.lastname: Fatigoni
authors.affiliation: Medical Oncology, S Maria Hospital, Terni, Italy.
authors.forename: Fausto
authors.initials: F
authors.lastname: Roila
keywords: kidney; lymph node metastases; lymphadenectomy; sarcoma; solitary fibrous tumor