Differential diagnosis of thyroid cysts by Ultrasound

Aims: High frequency ultrasound (US) and Tc99m radionuclide scanning (TC99m) are essential diagnostics for thyroid nodules. The TC99m differentiates “cold“ and “hot“ nodules. Cold nodule normally indicates an operation. We show that cystic nodules need differentiation by US and present four pitfalls during our clinical experience of one year.

Method: From May 2006 until June 2007 we operated on 460 patients with thyroid pathology. In 36% cases a “cold“ nodule indicated the operation. A fraction of those were cystic lesions which we retrospectively analysed. In four cases US lead to unusual diagnoses.

Result: Four patients which noticed a nodule in the neck presented in our clinic. In case one US revealed a cystic irregular nodule with septical flow. We suspected a carcinoma. Intraoperatively the diagnosis could be confirmed. In case two a man presented with a thyroid cyst. US revealed varicose vessels. Because of complaints we performed an operation. In case three a man presented a cystic tumour below the thyroid gland. US and laboratory findings revealed an adenoma of the parathyroid gland. In case four a lady presented half a year after thyroidectomy and neck dissection with a big cystic subclaviular nodule. Radionuclide scanning showed a low tracer uptake. US revealed a cystic tumour with marginal perfusion. The cervical exploration revealed a cystic degenerated metastasis of the known papillary carcinoma.

Conclusion: US is a good, time sparing and cheap procedure for differentiating cystic nodules. Our findings emphasize the requirement, technic and specials in case of the thyroid gland.