Metastatic renal cell carcinoma presenting as a thyroid nodule
Renal cell carcinoma accounts for approximately 3% of all
adult malignancies. It is associated with approximately
13,000 deaths annually. It has long been recognized as an
unpredictable tumor in its ability to recur many years after
initial diagnosis and for its ability to metastasize to
uncommon sites. Documented unusual sites include the
nasal cavity, gingiva, larynx, parotid gland, and thyroid.
Although secondary neoplasms of the thyroid are rare,
metastatic renal cell carcinoma is the most common type.
Here, we report the case of renal cell carcinoma
metastasizing to the thyroid 15 years after nephrectomy.
Renal cell carcinoma (RCC) has an unpredictable and diverse behavior. It most commonly metastasizes to the lungs,
liver, bone, and adrenal glands; however, metastasis to unusual sites, including the skin, testis, nasal cavity, gingiva,
and thyroid, may occur. Studies have demonstrated that approximately 25% of RCC patients have synchronous
disease at presentation and in many cases metastasis to the thyroid was the initial presentation of patients
subsequently diagnosed with RCC. Metachronous disease to the thyroid can occur after a latent disease-free period,
with the longest latent period recorded in the literature as 26 years.
In general, metastases to the thyroid gland is rare. The incidence of clinically significant metastases to the thyroid
from all malignant tumors is 2-3%. At autopsy the incidence has been reported in the range of 1.2 to 24.2%. Of the
clinically significant tumor types to metastasize to the thyroid, RCC carcinoma is the most common type, followed by
lung, colorectal, and breast carcinomas. A slightly higher than 150 cases of clinically recognizable metastatic RCC to
the thyroid have been reported. Overall average age is 62.1 years. Average latent interval after curative nephrectomy
is 7.5 years.
The thyroid gland is among the most vascularized organs in the body, second only to the adrenal glands. One would
expect metastasis to this organ more commonly, however it has been hypothesized that the rich blood supply, an
associated high oxygen tension, and large amounts of tissue iodine make the thyroid gland a poor host for
metastases by suppressing proliferation of metastatic malignant cells. Although metastases to the thyroid is rare,
many of these cases may go unrecognized and seen on autopsy. Additionally, it has been suggested that the thyroid
gland, when altered by goiter, neoplasms, and thyroiditis, is more vulnerable to metastatic growth due to metabolic
changes with a decrease in oxygen and iodine content.
The route of spread of RCC appears to be hematogenous, possibly bypassing the lungs. One theory suggests that
tumor cells may evade removal by the pulmonary circulation possibly via reversed blood flow through the
paravertebral venous plexus of Batson in situations of increased intrathoracic and intra-abdominal pressure.
Clinically, patients typically present with a painless, palpable thyroid nodule. It may be associated with dysphagia,
dyspnea, cough, and vocal changes. One case of acute airway failure from RCC metastasis to the thyroid has been
reported while are asymptomatic. They appear as hypoechogenic masses on ultrasound and cold nodules on iodine
131 scanning. Distinguishing metastatic RCC from primary thyroid tumors can be difficult. FNA is effective, although it
can be misleading because of the presence of a clear cell component in both RCC and thyroid follicular carcinoma.
Differentiating primary thyroid carcinoma from metastatic disease is best achieved by immunohistochemical staining.
Surgical resection is the recommended management of patients with solitary metastatic disease from RCC. In many
instances, lobectomy and isthmectomy may be sufficient in cases of solitary metastasis. Bilateral metastasis typically
require total thyroidectomy. The survival time in patients with synchronous thyroid metastases is a mean of 8
months. In metachronous thyroid disease, the mean is 10 years, and the longer the time interval between the
diagnosis of RCC and the appearance of thyroid metastasis, the better the prognosis.
Mrs. M.J. is an 84 y/o Hispanic female who presented to
her primary care physician with an uncomfortable right-
sided thyroid nodule of 1 month duration. During the
initial work-up, the patient was sent for a FNA of the
nodule, which was reported as suspicious for papillary
thyroid carcinoma. She was sent to our surgical oncology
clinic for further care. The patient was asymptomatic
Her past medical history was consistent with D.M., HTN,
and left renal cell carcinoma. Surgical history was only
significant for a left radical nephrectomy, which was
performed in 1998. The patient is married. She is a non-
smoker and non-drinker. She is noted to be a Jehovah’s
Witness and would not accept blood transfusion if
Her physical exam demonstrated an approximately 0.5
cm, firm, palpable right thyroid nodule. Her thyroid
function tests were normal. Based on these findings, the
diagnosis of thyroid carcinoma was made, and the patient
was scheduled for right thyroid lobectomy with frozen
The patient was taken to the operating room at
NSUCOM/Larkin Community Hospital. The tumor was
resected with the use of the NIM device and frozen
sections were obtained. Frozen sections at the time of
surgery were reported as papillary thyroid carcinoma,
consistent with previous reports. Total thyroidectomy was
performed with minimal blood loss and no complications.
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Metastatic Renal Cell Carcinoma Presenting as a
Joshua Simon, DO, PGY-1, Philip Pack, DO, PGY-2, Quoc Dang, DO, PGY-1, Michael Kambour, MD, and Mohammad Masri, MD (NSUCOM/ Larkin
Community Hospital General Surgery Residency Program Director)
C. Immunoperoxidase CD-10 to confirm renal cell
B. Permanent section from total thyroidectomy
showing renal cell carcinoma.
A. Frozen section from thyroidectomy
showing renal cell carcinoma.
D. Thyroid transcription factor -1 stain used to
help confirm the tissue is not from the thyroid.
Fifteen years after left radical nephrectomy.
Two weeks after total thyroidectomy.
RCC is a unique tumor with an unpredictable and non-
discriminatory route of spread. Our case report adds to the
expanding literature of latent thyroid metastasis from RCC
many years after nephrectomy. Therefore, it is important to
think about the possibility of metastatic RCC in patients with
a previous nephrectomy and a thyroid nodule. If metastatic
RCC is limited to the thyroid only, surgical resection offers
the ability to cure stage IV disease.