Diagnostic dilemma: Papillary thyroid carcinoma and multiple pulmonary nodules

Issue: April 2008

BySara M. Pietras, MD

ByStephanie L. Lee, MD, PhD, ECNU

A 60-year-old woman was referred for the evaluation of a goiter. She had noticed slow growth of her thyroid for the past 40 years, and it was now causing a globus sensation when she swallowed and mild neck discomfort when lying on her right side. She denied any change in her voice, shortness of breath or hemoptysis. She denied a history of head and neck radiation. She was born in Barbados and two of her sisters had thyroid surgery for unknown reasons.

Sara M. Pietras

Stephanie L. Lee

Her exam demonstrated a healthy-appearing comfortably-breathing woman. Her thyroid was firm, six to seven times enlarged, and more prominent on the right. It was non-tender and mobile when she swallowed.

The patient had recently been to the emergency department where a chest X-ray showed a pulmonary nodule. A computed tomography scan of the neck showed an asymmetrically enlarged goiter with central calcification and tracheal deviation without compression (Figure 1). A CT of the thorax (Figures 2A and 2C) showed numerous round scattered pulmonary nodules ranging in size from several millimeters to 1.3 cm. A spiculated lesion measuring 1.4 × 1.0 cm in the left upper lobe of the lung was morphologically different from the other pulmonary nodules. Her thyroid-stimulating hormone was 2.78 (reference range 0.35 mIU/L to 4.5 mIU/L) with a thyroglobulin level of 5,924 (reference range 1 ng/mL to 55 ng/mL) and negative thyroglobulin antibodies.

Figure 1: Axial section of a CT of the neck (A) and high resolution ultrasound (B, C) of the enlarged right lobe of the thyroid (white arrow) with the calcified mass (red arrowhead) and tracheal deviation (blue arrowhead). The sagittal view of a high resolution ultrasound demonstrated a diffusely enlarged right thyroid lobe with a heterogeneous, hypoechoic echotexture (B). Increased intranodular vascularity was found with Doppler analysis (C). Discrete nodules and microcalcifications were not noted.

Figure 2: Computed tomography scan and I-123 single photon emission computed tomography scintigraphy. Coronal (A) and axial (C) images from the CT scan of the thorax showing a spiculated mass (red arrowhead) in the anterior aspect of the left upper lobe and numerous rounded nodules (blue arrows). A coronal image from a SPECT scintigraphy of the thorax (B) shows the spiculated mass is non-iodine avid (black arrow).

Photos courtesy of Boston Medical Center

Fine needle aspiration biopsies of the right thyroid lobe showed follicular cells in a predominately microfollicular pattern consistent with a follicular lesion. Total thyroidectomy was performed showing bulky enlargement of the right lobe adherent to a portion of the right internal jugular vein. A segmental resection of the jugular vein was performed to mobilize the thyroid. Surgical pathology revealed an 11-cm papillary carcinoma with invasion into the right jugular vein.

Figure 3: 2 mCi I-123 whole body scintigraphy with planar images of the anterior (A) and posterior (B) views with radioiodine uptake in multiple discrete foci in the thyroid bed (red arrows) and scattered primarily throughout the posterior lung fields (blue arrows). There is no iodine-avid pulmonary disease in the anterior portion of the left upper lobe of the lung.

Subsequent to the thyroidectomy, a hypothyroid 2 mCi I-123 whole body scintigraphy (Figure 3) showed 6.4% uptake in multiple discrete foci in the thyroid bed and 1.2% uptake in multiple areas of focal uptake mostly in the posterior portion of both lung fields. A comparison between the CT scan of the chest and planar and single photon emission computed tomography images of the radioiodine whole body scan indicated that the isolated spiculated lesion was not iodine-avid (Figure 2A and 2B). The patient was treated with 200 mCi of I-131 for distant metastatic papillary thyroid carcinoma. A post-treatment whole body scan one week later demonstrated the same pattern of uptake in the neck and chest. A positron emission tomography scan was negative for increased metabolic activity in this lesion or the iodine-avid lesions in the neck and chest.

After 9 months, she has no pulmonary complaints and her thyroglobulin level is 115 ng/mL with negative thyroglobulin antibodies with a TSH <0.01 mIU/L. The noniodine-avid spiculated pulmonary mass has been stable in size on serial CT scans of the chest for the past year, and the rounded iodine-avid nodules have measurably decreased in size since the I-131 treatment.

This patient initially posed a diagnostic and therapeutic problem because of the presence of a single spiculated mass in addition to the rounded pulmonary lesions. Although the initial clinical impression was that the locally invasive papillary thyroid carcinoma and numerous round pulmonary nodules in the setting of an extremely high thyroglobulin level most likely represented distant metastatic papillary thyroid cancer, it was unclear if the spiculated lesion was a primary lung cancer that could potentially prove more life-threatening than the patient’s thyroid cancer. The appearance of the spiculated mass is not typical of metastatic papillary thyroid carcinoma. However, the mass was not metabolically active as shown by the negative PET scan and has not changed in size after nine months. The conclusion is that this is likely a primary pulmonary carcinoma with very indolent behavior, but the diagnosis would have been missed unless there is close attention to match abnormal masses seen on imaging studies and iodine-avid disease on the radioiodine scan. Potentially, if this had been an aggressive pulmonary carcinoma, delay of diagnosis would have been life-threatening.

She will be followed closely with serial serum thyroglobulin levels and thorax CT scans. If the spiculated mass enlarges and her widely metastatic papillary thyroid carcinoma is stable or regresses from the radioactive iodine therapy, it will be resected by video-assisted thoracic surgery. Current plans are to repeat the radioiodine therapy in about three months.

Sara M. Pietras, MD, is a Fellow at Boston University School of Medicine.

Stephanie L. Lee, MD, PhD, is an Associate Professor of Medicine at Boston University School of Medicine and Director of Endocrine Clinics at the Boston Medical Center.

For More Information:

Fraser RS, Muller NL, Colman N, Pare PD. Fraser and Pare’s Diagnosis of Diseases of the Chest. Vol 2. 4th ed. Philadelphia: W.B. Saunders Co; 1999, 1406 p.