A Pediatric Radiology Textbook and Pediatric Radiology Digital Library
Pediatric Thyroid Cancer
Etiology: — Biological behavior different than in adults – typically well differentiated papillary (95%) or follicular (5%) subtypes in children — Medullary thyroid cancer rare and associated with hereditary cancer syndromes: MEN or familial MTC — Anaplastic and Hurthle cell subtypes also rare in children
Imaging approach on US: — Distinguish cystic from solid lesions as cystic lesions typically benign but up to 50% of lesions have cystic component and 8% of cystic lesions represent malignancies — Quantitate size and number of nodules — Assess for presence of cervical lymphadenopathy — Detect non-palpable lesions — Guide fine needle aspiration
Imaging approach on CT and MRI: — Useful in assessing local invasion and determining nodal and distant metastases
Imaging US sonographic features suggestive of thyroid malignancy: — Solid composition — Hypoechoic to very hypoechoic — Microcalcifications — Irregular margins — Taller than wider shape — Increased and distorted vascularity
Imaging US sonographic features suggestive of benign nodules: — Likelihood of malignancy in purely cystic nodules is less than 1% — Purely cystic or mainly cystic: Anechoic, posterior acoustic enhancement, well-defined margins, colloid (ring down artifact), may have mural solid components — Spongiform: numerous small cystic spaces in large proportion of nodule
Note: — Don’t worry or worry less if nodule is purely cystic, spongiform or predominantly cystic, with comet-tail artifacts — Worry if nodule is hypoechoic, solid, shows microcalcifications, taller than wide, with infiltrative margins, extrathyroidal extension and cervical metastasis — Malignant solid nodules: Demonstrate indistinct margins, variable echotexture, increased intra-nodular blood flow, microcalcifications — Benign solid lesions: More likely to exhibit homogenous echotexture, have translucent halo, lack internal calcifications
DDX:
Complications:
Treatment: Surgical
Clinical: — Risk factors: Radiation exposure or prior malignancy or chronic inflammation or family history or predisposition syndromes — Lower incidence of thyroid nodules in children but higher risk of malignancy when nodule is identified – 10% of thyroid cancer occurs in less than 21 years old and children typically present with advanced disease at diagnosis (extensive regional nodal involvement in 60-80%, higher rate of distant metastases – lung in 10-20%, bone is rare less than 5%, multifocal disease common) — Higher local and distant recurrence rates — Thyroid nodules incidence is 1-5% and 26% of those nodules harbor cancer — Decision to biopsy based on US characteristics of nodule and clinical context — Recurrence rate is 40%
Radiology Cases of Papillary Thyroid Cancer
Sagittal US of the right neck (above) shows an enlarged lymph node that does not have a normal fatty echogenic hilum and that does have several microcalcifications within it. Transverse US of the thyroid gland (below) shows a mass in the right lobe of the thyroid gland that contains numerous microcalcifications.
Clinical Cases of Follicular Thyroid Adenoma
Clinical images show a large nodule in the right lobe of the thyroid gland which was easily palpable.
Histopathology Cases of Follicular Thyroid Adenoma
Histopathological image lower power photomicrograph of a H&E stained section shows a well-encapsulated mass which is strikingly different from the adjacent thyroid tissue.Histopathological image higher power photomicrograph shows numerous follicles with minimal variation in size. The lack of adenomatous change in the adjacent thyroid tissue would support a diagnosis of follicular adenoma, although on occasion, the distinction between a hyperplastic nodule of a goiter and a follicular adenoma may be almost impossible.Histopathological image higher power photomicrograph shows numerous follicles with minimal variation in size. The lack of adenomatous change in the adjacent thyroid tissue would support a diagnosis of follicular adenoma, although on occasion, the distinction between a hyperplastic nodule of a goiter and a follicular adenoma may be almost impossible.
