title: Renal cell carcinoma metastasis to the parathyroid gland: A very rare occurrence.
abstract: BACKGROUND
  Metastases to the parathyroid gland are very uncommon. Although renal cell carcinoma metastasis to the head and neck region is well recognised, with a predilection for unpredictable metastasis to unusual sites such as the thyroid gland, nose, paranasal sinuses, and cranial bones, there are no reports of parathyroid gland involvement.
  
  
  METHODS
  We describe an unusual case of renal cell carcinoma metastasis to a parathyroid gland in a 69-year-old male who had been treated 8 years previously for a pT3b N0 M1 clear cell carcinoma of the right kidney with a right nephrectomy, and interferon immunotherapy for 18 months. The patient had originally presented to the plastic surgeons with a rapidly enlarging 3cm superficial lesion on the ventral aspect of the left forearm, which was excised with histology revealing metastatic renal (clear) cell carcinoma.
  
  
  CONCLUSIONS
  Renal cell carcinoma has a reputation for unpredictable patterns of metastasis, and our case highlights this, with the first description in the literature of parathyroid gland metastasis. Despite the poor prognosis associated with metastatic renal cell carcinoma, our patient is still alive 10 years following original presentation, despite having metastasis to two different extra-renal sites and a shortened course of initial adjuvant systemic therapy.
  
  
  CONCLUSIONS
  In parathyroid gland metastasis, metastectomy can offer excellent local long term local control.
authors.affiliation: Department of Otolaryngology-Head & Neck Surgery, Guy's & St Thomas' NHS Foundation Trust, Great Maze Pond, SE1 9RT London, United Kingdom.
authors.forename: Enyinnaya
authors.initials: E
authors.lastname: Ofo
authors.affiliation: Academic Section of Vascular Surgery, Imperial College London, 4 North Charing Cross Hospital, Fulham Palace Road, W6 8RF London, United Kingdom. Electronic address: rishimandavia@gmail.com.
authors.forename: Rishi
authors.initials: R
authors.lastname: Mandavia
authors.affiliation: Department of Otolaryngology-Head & Neck Surgery, Guy's & St Thomas' NHS Foundation Trust, Great Maze Pond, SE1 9RT London, United Kingdom.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Jeannon
authors.affiliation: Head and Neck/Oral Pathology, King's College London and Guy's & St Thomas' NHS Foundation Trust, Great Maze Pond, SE1 9RT London, United Kingdom.
authors.forename: Edward
authors.initials: E
authors.lastname: Odell
authors.affiliation: Department of Otolaryngology-Head & Neck Surgery, Guy's & St Thomas' NHS Foundation Trust, Great Maze Pond, SE1 9RT London, United Kingdom.
authors.forename: Ricard
authors.initials: R
authors.lastname: Simo
keywords: Head and neck neoplasms; Metastasis; Parathyroid gland; Renal cell carcinoma