Schilddrüsenknoten mit randständigen Verkalkungen (Eierschalen)

Ultrasonography

of thyroid nodules: a pictorial review. (a) A benign nodule. It is iso-echoic relative to the thyroid, and surrounded by a hypo-echogenic halo. (b) A benign cystic nodule with multiple colloids, which are seen as hyper-echoic spots with comet-tail. (c) A benign nodule with hypo-echoic cystic spaces resulting in a spongiform or honeycomb appearance. (d) A benign nodule with eggshell calcification. Note the acoustic shadowing produced by the calcific ring. (e) A benign nodule with eggshell calcification. (f) A benign nodule with peripheral vascularity on Doppler assessment

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Thyroid nodules are any discrete lesion that can be delineated on imaging studies from the adjacent thyroid parenchyma. They can represent a range of benign or malignant conditions.

Epidemiology

They are more common in females (4:1 F: M) and have an increasing prevalence with increasing age and reduced iodine intake . The incidence is estimated at 0.1% with a lifetime prevalence of 10% .

Clinical presentation

Thyroid nodules are a common incidental finding on imaging (see: incidental thyroid nodules), present in ~10% of CT and MRI neck examinations, ~50% (range 20-76%) of ultrasound neck ultrasound, and 55% (range 50-65%) of autopsies . They can also be found on clinical examination as palpable lesions in the neck, although this clinical finding does not represent a thyroid nodule if there is no imaging correlate.

When symptomatic, patients may present with thyroid dysfunction or rarely compressive symptoms .

Pathology

Thyroid nodules are typically benign. The prevalence of malignancy (based on biopsy) in thyroid nodules is ~10% (range 4-6-15%) .

Etiology

There are many causes of thyroid nodules, some of the more common causes are listed below:

benign nodules
- follicular adenoma
  - colloid nodule
- Hurthle cell adenoma
- thyroid cyst: simple, hemorrhagic
- focal/asymmetrical thyroiditis
  - lymphocytic (Hashimoto) thyroiditis
  - granulomatous (de Quervain) thyroiditis
malignant nodules
- primary thyroid cancer
  - papillary thyroid carcinoma
  - follicular thyroid carcinoma
  - Hurthle cell carcinoma
  - poorly differentiated carcinoma
  - medullary thyroid carcinoma
  - anaplastic thyroid carcinoma
- thyroid lymphoma: primary or secondary
- metastases to the thyroid

Radiographic features

Ultrasound is the modality of choice for diagnostic assessment of thyroid nodules . It also allows for ultrasound-guided fine-needle aspiration of selected nodules.

Treatment and prognosis

As thyroid nodules are commonly incidental, there are numerous classification systems to help with risk stratification. See article: Incidental thyroid nodules for further detail.