title: C1-C2 pigmented villonodular synovitis and clear cell carcinoma: unexpected presentation of a rare disease and a review of the literature.
abstract: BACKGROUND
  Pigmented Villonodular synovitis (PVNS) is a rare vertebral pathology--around 50 reports, only 3 concerning C1-C2 location.
  
  
  METHODS
  A 64-year-old man, submitted to a right nephrectomy for a clear cell carcinoma, presented with an asymptomatic osteolytic C1-C2 lesion. Even though the diagnosis of metastatic disease was the most probable, the presence of a solitary lesion without other osseous or systemic localization and the predicted low risk of recurrence imposed a surgical biopsy. A pigmented villonodular synovitis diagnosis was made, a rare vertebral pathology--around 50 reports, only 3 concerning C1-C2 location. No further treatment was assigned precluding the iatrogenic consequences of empirical treatments based on clinical diagnosis with no histopathological support. The patient remains stable at 18 months of follow-up.
  
  
  CONCLUSIONS
  A large differential diagnosis should be made when the typical findings for metastatic disease are absent precluding the iatrogenic consequences of empirical treatments based on clinical diagnosis with no histopathological support.
authors.affiliation: Neurosurgical Department, Hospital Santa Maria, Lisbon, Portugal, jose.pedro.lavrador@gmail.com.
authors.forename: José Pedro
authors.initials: JP
authors.lastname: Lavrador
authors.forename: Edson
authors.initials: E
authors.lastname: Oliveira
authors.forename: Nuno
authors.initials: N
authors.lastname: Gil
authors.forename: António Fernandes
authors.initials: AF
authors.lastname: Francisco
authors.forename: Sérgio
authors.initials: S
authors.lastname: Livraghi
mesh_terms: D018262:Adenocarcinoma, Clear Cell / Q000150:complications* / Q000175:diagnosis / Q000556:secondary; D002574:Cervical Vertebrae; D003937:Diagnosis, Differential; D006801:Humans; D007680:Kidney Neoplasms / Q000150:complications* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D035583:Rare Diseases / Q000150:complications / Q000175:diagnosis*; D013586:Synovitis, Pigmented Villonodular / Q000150:complications / Q000175:diagnosis*