title: Case report of pigmented villonodular synovitis arising from the calcaneocuboid joint in a 12 year old male.
abstract: BACKGROUND
  Pigmented villonodular synovitis (PVNS) is a benign proliferative disorder of the synovium of unknown aetiology. It usually presents in adults between the ages of 30 and 40 years of age and is rare in the paediatric population. In the literature, there are a total of 43 cases of PVNS affecting the paediatric population and only one case affecting the calcaneocuboid joint.
  
  
  METHODS
  We report a case of diffuse PVNS affecting the calcaneocuboid joint of a 12 year old male. The patient presented with a 3 month history of a painless swelling affecting the lateral aspect of the hindfoot region with no preceding history of trauma. Examination revealed a lesion which was firm in texture, originating in the region of the calcaneocuboid joint, and clinically appeared to originate from deeper structures with no overlying skin changes or warmth. Routine blood tests were within normal limits. Radiographs demonstrated an erosive lesion into the calcaneocuboid joint and magnetic resonance imaging demonstrated a lesion consistent with PVNS.
  
  
  RESULTS
  Following surgical excision of the lesion, the patient recovered to full activities after a brief period of immobilisation in plaster to allow wound healing. At six months follow-up, there was no evidence of recurrence.
  
  
  CONCLUSIONS
  Our case report of PVNS involving the calcaneocuboid joint is only the second report in the literature and highlights the importance of considering PVNS as a differential diagnosis in children presenting with swelling of the foot and ankle with normal blood and clinical parameters. The combination of the case report along with radiographic and magnetic resonance imaging and intra-operative photographs also aids the reader in understanding of the condition.
authors.affiliation: Department of Trauma and Orthopaedics, Royal Derby Hospital, Uttoxeter Road, Derby Road, DE22 6NE, United Kingdom. Electronic address: nickduncan@doctors.net.uk.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Duncan
authors.affiliation: Department of Trauma and Orthopaedics, Royal Derby Hospital, Uttoxeter Road, Derby Road, DE22 6NE, United Kingdom.
authors.forename: Rohan
authors.initials: R
authors.lastname: Rajan
mesh_terms: D000367:Age Factors; D002648:Child; D006801:Humans; D008297:Male; D013586:Synovitis, Pigmented Villonodular / Q000175:diagnosis* / Q000601:surgery*; D013640:Tarsal Joints
keywords: Pigmented; Synovitis; Villonodular