ADENOMA OF HETEROTOPIC THYROID TISSUE
This 27 year old female presented with a 20-year history of difficulty in swallowing and the feeling of a "lump" at the back of the throat. On examination the only abnormality was a large red mass, smooth and hemispherical in shape which was attached to the base of the tongue and measured 4 x 2 x 2 cm. At operation this lump was excised and recovery was uneventful.
The specimen consists of an ovoid mass of glandular tissue 4.5 cm in maximum diameter, which has been hemisected and the two halves opened like the leaves of a book. Approximately half of the external surface of the mass is covered by a mucosal layer. The remainder is haemorrhagic. The cut surface of the nodule resembles thyroid tissue. There is a little patchy haemorrhage and cystic change. Histological examination showed this to be an adenoma of mixed colloid storage and foetal type arising in heterotopic thyroid tissue. Thyroid tissue is sometimes found at the base of the tongue due to faulty embryological descent.