Individuals with DICER1 variation are more likely to have thyroid nodules. Most thyroid nodules in individuals with DICER1 variation are benign although there is an increased risk for thyroid cancer. Most DICER1-related thyroid cancer is well differentiated and associated with a favorable prognosis.
Thyroid ultrasound can determine the number, location and size of thyroid nodules and may offer additional information which can suggest which nodules may represent cancer.
The approach to pre-operative investigation is the same for patients with a thyroid nodule with or without DICER1 variation. Ultrasound is used to confirm the nodule and to determine whether fine needle aspiration (FNA) is warranted. In general, fine needle aspiration is recommended for nodules measuring 1 cm or greater. Depending on the results of the fine needle aspirate, additional surgery or other intervention may be indicated.
A range of benign to malignant lesions of the thyroid is seen in individuals with DICER1 variation. The most common benign lesion is multinodular or adenomatous hyperplasia, characterized by variably sized follicular nodules. There may be accompanying lymphocytic thyroiditis. The most common thyroid malignancy is papillary thyroid carcinoma with either the classic papillary pattern or follicular variant.
Observation or surgery are the most common modalities used in individuals with thyroid nodules. Additional evaluation with fine needle aspirate may be indicated as above.
Radioactive iodine (RAI) is the most effective medical treatment for patients found to have distant metastasis or to treat patients with persistent disease that is not amenable to repeat surgery.
Individuals and families should be counseled regarding the increased risk for thyroid nodules and cancer. We recommend a thyroid US at approximately 8 years of age in children with DICER1-related conditions and then every 2 to 3 years, or as needed for worrisome signs or symptoms, including an enlarged thyroid, one or more thyroid nodules or persistent cervical lymphadenopathy. For individuals receiving chemotherapy or radiation treatment for a nonthyroid malignancy (e.g., for PPB or pineoblastoma), a baseline thyroid US should be performed at the time of diagnosis and then annually for 5 years after exposure, decreasing to every 2 to 3 years if no lesions are found on initial US exams. Generally standard criteria are used to determine the need for fine needle aspiration if ultrasound shows concerning findings. For patients undergoing thyroid surgery based on fine needle aspirate results, complete US assessment of lateral neck lymph nodes per standard guidelines must be performed prior to surgery to ensure that a lateral neck lymph node dissection is not warranted.