Squamous cell carcinoma of the thyroid gland: primary or secondary disease?
OBJECTIVE
To review the aetiopathogenesis, clinical characteristics, immunohistochemical profile, prognosis and treatment options for primary thyroid squamous cell carcinoma, and to compare it with squamous cell carcinoma metastatic to the thyroid, thus providing the reader with a framework for differentiating primary and secondary disease.


METHODS
Review of English language literature from the past 25 years.


METHODS
A search of the Medline, Embase and Cochrane databases (April 1984 to April 2009) was undertaken to enable a comprehensive review.


RESULTS
After applying strict criteria for the diagnosis of primary thyroid squamous cell carcinoma, 28 articles were identified reporting 84 cases. When reviewing secondary thyroid squamous cell carcinoma, we only analysed cases of squamous cell carcinoma metastatic to the thyroid gland, and found 28 articles reporting 78 cases.


CONCLUSIONS
It is possible to differentiate between primary and secondary thyroid squamous cell carcinoma, on the basis of combined evidence from clinical examination and endoscopic, pathological and radiological evaluation. Such differentiation is important, as the prognosis for primary squamous cell carcinoma is uniformly poor irrespective of treatment, and the most suitable option may be supportive therapy. Treatment for secondary squamous cell carcinoma of the thyroid varies with the site and extent of spread of the primary tumour.
Syed
M I
MI
Department of Otolaryngology and Head and Neck Surgery, Southern General Hospital, Greater Glasgow and Clyde NHS Trust, Glasgow, UK. iqbalms@hotmail.com
Stewart
M
M
Syed
S
S
Dahill
S
S
Adams
C
C
McLellan
D R
DR
Clark
L J
LJ
D000402:Airway Obstruction / Q000209:etiology / Q000601:surgery; D002294:Carcinoma, Squamous Cell / Q000401:mortality / Q000473:pathology / Q000556:secondary; D003131:Combined Modality Therapy; D003937:Diagnosis, Differential; D018450:Disease Progression; D004724:Endoscopy; D006801:Humans; D008279:Magnetic Resonance Imaging; D010166:Palliative Care / Q000379:methods; D011379:Prognosis; D015996:Survival Rate; D013964:Thyroid Neoplasms / Q000401:mortality / Q000473:pathology / Q000556:secondary; D014057:Tomography, X-Ray Computed