This article is more than 5 years old. Information may no longer be current.
Clinical correlation required
Click Here to Manage Email Alerts
An 83-year-old woman was sent to me because of a large right thyroid mass. A CT scan revealed a large right thyroid mass with suspicious adenopathy. She had not noticed this herself until it was brought to her attention by her physicians.
The ultrasound showed a heterogeneous thyroid consistent with Hashimoto’s thyroiditis. The right lobe was markedly enlarged with a 5 cm x 4 cm mass taking up almost the entire lobe. Multiple enlarged lymph nodes were also present, the largest of which was 3.3 cm x 2.3 cm at right level III. It appeared to be invading or pressing upon the jugular. This lymph node was very suspicious for metastatic disease. It was heterogeneous in appearance with chaotic increased flow.
I performed ultrasound-guided fine-needle aspiration of the thyroid mass. The FNA report was: “Negative for malignancy, specimen adequate for diagnosis. Follicular epithelium, Hürthle cell change and numerous lymphocytes consistent with a benign thyroid nodule on background of Hashimoto's thyroiditis; clinical correlation required.”
It is those last three words which I consider to be the most important: “clinical correlation required.” I advised her to have surgical resection of the thyroid mass and biopsy of the suspicious lymph node. I have seen false-negative FNA in thyroid lymphoma before and did not want to miss the diagnosis again. Another possibility is that this thyroid mass was only an incidental finding and the enlarged lymph nodes were metastases from another source. The pathology confirmed diffuse large B-cell lymphoma; the patient will be seeing oncology.
Primary thyroid lymphoma is rare. It is only about 1% to 5% of all thyroid malignancy and <2.5% of all lymphoma. The most common thyroid lymphoma is diffuse large B-cell lymphoma followed by mucosa-associated lymphoid tissue lymphoma, follicular lymphoma and other forms. The classic presentation is an elderly woman with pre-existing Hashimoto’s thyroiditis and a new thyroid mass rapidly increasing in size.
Thyroid lymphoma occurs almost exclusively in association with Hashimoto’s thyroiditis. The underlying cause is unclear but hypothesized to be due to immunologic stimulation of lymphocytes by the chronic thyroiditis, resulting in the development of malignant cells. Although the risk of thyroid lymphoma is increased in individuals with Hashimoto’s thyroiditis compared to those without, the absolute risk is still low.
In the past, extensive surgery was the mainstay of treatment. However, the advent of multi-agent chemotherapy and radiotherapy has resulted in surgery taking a less prominent role. One problem with FNA is the possibility for false-negatives. Surgical biopsy is often necessary to make the diagnosis. Immunohistochemistry and flow cytometry combined with FNA improves the ability to distinguish between thyroid lymphoma and chronic lymphocytic thyroiditis but is not available everywhere.
Cases such as this remind me why the most essential factor in the evaluation of a patient continues to be the inquisitive clinician. Pay attention to your clinical intuition, trust your gut instinct and keep in mind previous experience. If something does not seem quite right, it probably isn’t.