Case Author(s): J. Philip Moyers, M.D. and Farrokh Dehdashti, M.D. , 10/1/95 . Rating: #D1, #Q4

Diagnosis: Metastatic papillary thyroid carcinoma to the lungs and neck

Brief history:

Patient is status post thyroidectomy for papillary carcinoma with follicular variant.


Anterior and posterior whole body I-131 images

View main image(tr) in a separate image viewer

Full history/Diagnosis is available below

Diagnosis: Metastatic papillary thyroid carcinoma to the lungs and neck

Full history:

18-year old woman with papillary carcinoma of the thyroid status post total thyroidectomy with removal of lymph nodes in the neck and supraclavicular regions. MRI demonstrated multiple pulmonary nodules.


200 mCi I-131 sodium iodide p.o.


Anterior and posterior whole body I- 131 images demonstrate multiple areas of increased uptake in the neck, as well as diffuse pulmonary uptake.


Well differentiated papillary, follicular, and mixed carcinomas are represented in about 75% of all primary thyroid malignancies. The overall 5-year survival rate of well differentiated carcinoma is over 95% in properly treated patients. Papillary carcinomas tend to metastasize via the interstitium to local nodal groups while follicular carcinomas tend to metastasize hematogenously. The remaining thyroid malignancies include poorly differentiated anaplastic thyroid carcinoma and medullary carcinoma of the thyroid. Medullary carcinoma of the thyroid may be seen in multiple endocrine neoplasia type IIA and IIB. At our institution, after a total or subtotal thyroidectomy, I- 131 whole body imaging is usually performed to evaluate for metastatic disease. If metastatic disease is demonstrated or if residual activity is demonstrated within the neck, and it is unclear whether this represents metastatic disease or functioning residual thyroid tissue, the patient receives an ablative dose of I-131. In this case, metastatic disease was suspected on the basis of multiple pulmonary nodules demonstrated on MRI. Therefore, an ablative dose was given prior to a diagnostic dose and imaging was performed after the ablative dose of 200 mCi of I-131. To achieve maximum sensitivity in detecting functioning lesions, follow-up whole-body I-131 imaging is usually performed 4-6 weeks after the patient has been removed from thyroid supplementation so that the patient has an elevated TSH. Follow-up imaging may be done at 6 month intervals (at shorter intervals in patients with extensive or progressive disease and longer intervals in patients with stable or slowly progressive disease) until disease is eradicated and after which imaging may be performed at 3-5 year intervals in patients with high risk of recurrence. Since the dose is greater than 30 mCi, the patient must be hospitalized according to NRC regulations. In this case, multiple small pulmonary nodules were demonstrated on MRI. Other malignancies which can present as diffuse multiple small pulmonary nodules include a GI malignancy, usually pancreas, and GU malignancies, usually renal cell carcinoma.

References: 1) Mettler FA. Essentials of Nuclear Medicine Imaging. 1991 (3rd edition). 2) McDougall IR. Thyroid Disease in Clinical Practice. New York, NY: Oxford University Press, 1992 (1st edition).

Update 7/98. NRC regulations now allow larger doses to be administered as an outpatient, provided one first documents the clearance rate from the patient so that dosimetry to family members can be calculated.


The patient had MRI of the chest, which showed multiple pulmonary nodules.

Major teaching point(s):

In order to diagnose metastatic thyroid carcinoma, the normal biodistribution of I-131 should be known. Normal biodistribution of I-131 includes the salivary glands, stomach, kidneys, and bowel. The lungs are not a normal site of I-131 accumulation and if lung activity is demonstrated, diffuse pulmonary metastatic disease is the diagnosis.

ACR Codes and Keywords:

References and General Discussion of Thyroid Scintigraphy (Anatomic field:Face, Mastoids, and Neck, Category:Neoplasm, Neoplastic-like condition)

Search for similar cases.

Edit this case

Add comments about this case

Read comments about this case

Return to the Teaching File home page.

Case number: tr003

Copyright by Wash U MO