Thyroid cyst - Do we need to be concerned?


R Kadiyala; JF Todd. Imperial Centre For Endocrinology, Imperial College Healthcare NHS Trust, Hammersmith Hospital.


A 56 year old lady was referred by her GP with gradually enlarging thyroid gland for over 2 years. She reported noticing a swelling in her neck five to six years ago, but has been gradually getting bigger in size over the last 12 to 24 months.  She denied any pain, discomfort or any compressive symptoms.  TFT's were normal with FT4 of 15.5 pmol/L and TSH of 2.05 mu/L.Past medical history included asthma, migraines and vitamin D deficiency.  There was no previous exposure to radiation. Her father had suffered from throat cancer , died at the age of 75 and she wondered if she had something similar. 


Clinically she was euthyroid with a palpable solid thyroid gland measuring approximately 3 to 4 cm. There was no palpable lymphadenopathy or retrosternal extension.


An ultrasound scan of thyroid showed a 3 cm benign looking simple cyst occupying most of the right lobe of thyroid. Left lobe of thyroid was essentially normal and there was no lymphadenopathy. Report stated completely benign appearances with no sinister features. Patient was reassured after the USS examination. However in view of the size, A FNAC was performed and histology revealed features suggestive of papillary thyroid carcinoma (Thy4).


With the knowledge of the FNAC findings, a repeat thyroid ultrasound was performed which  showed 3 cm cystic lesion as noted previously but on this occasion a thickened wall with frond like projections and septa consistent with papillary thyroid carcinoma with cystic degeneration was reported. She has been referred to surgeons for total thyroidectomy and lymph node clearance.


Discussion: Cystic thyroid nodules are common and majority of these are usually benign degenerating thyroid adenomas. Among thyroid cancers associated with cyst, papillary thyroid cancer is most common. Our case demonstrates that ultrasound guided FNA remains gold standard in evaluation of cystic thyroid disease and usually requires tissue obtained from the cyst wall but occasionally malignant cells are present in cyst fluid.