Conference Coverage

ITC 2015: Review IDs features to aid thyroid lymphoma diagnosis


AT ITC 2015

LAKE BUENA VISTA, FLA. – Rapidly enlarging thyroid masses with compressive symptoms may signal thyroid lymphoma, according to findings from a review of cases at the Mayo Clinic.

Radiologically, these masses tend to present as large, unilateral, thyroid-centered masses that are hypoechoic on ultrasound and that expand into adjacent soft tissue, Dr. Anu Sharma reported at the International Thyroid Congress.

The findings are based on a review of 75 patients with biopsy-proven thyroid lymphoma – a relatively rare disease, accounting for between 1% and 5% of all thyroid malignancies, and less than 1% of all lymphomas – who presented to the Mayo Clinic between 2000 and 2014.

“Thyroid lymphoma can sometimes present very similar to anaplastic carcinoma, and we wanted to see if there are any unique identification factors that you can use to increase your suspicion of thyroid lymphoma,” Dr. Sharma of the Mayo Clinic, Rochester, Minn., said.

Indeed, rapid enlargement and compressive symptoms are also common presenting features of anaplastic carcinoma, she said.

Of the 75 cases included in the review – compromising all cases presenting during the study period – 70.7% involved primary thyroid lymphoma. A neck mass was present in 88% of cases, dysphagia in 45%, and hoarseness in 37%.

The typical presentation included a solid, hypoechoic mass with mildly increased vascularity, no internal calcifications, and edge characteristics that ranged from well-defined (80%) to ill-defined (20%). Median tumor volume was 64 cm3, Dr. Sharma said.

This differs from anaplastic carcinoma in that most patients with anaplastic carcinoma have ill-defined edges, she noted.

Another difference between thyroid lymphoma and anaplastic carcinoma as noted in this study involves necrosis; none of the patients in the current study had areas of necrosis, whereas 78% of anaplastic carcinoma patients in another study had areas of necrosis, she explained.

The patients in the current study had a median age of 67 years, although the ages varied widely. About half (50.7%) were men, and 54.7% had a history of Hashimoto’s thyroiditis. Fifty-seven of the patients had an ultrasound before treatment.

The first diagnostic procedure performed was fine needle aspiration (FNA) in 65 subjects, and the FNA biopsies were abnormal in 69% of those, with 42% suggesting a specific lymphoma subtype. The subtype diagnosis was accurate, based on final tissue analysis, in 89% of those.

“While this is quite impressive, all patients who had FNA ended up having further tissue biopsy for subtype confirmation and for treatment, and this is important, because the subtype of the lymphoma is important in determining the type of treatment uses as well as determining prognosis,” she said.

The diagnosis was confirmed by core biopsy in 46.7% of cases, by incisional biopsy in 9.3%, by partial or total thyroidectomy in 25.3%, and by lymph node biopsy in 13.3%; percentages total 94.6% due to downward rounding. Histologic subtypes included diffuse large B-cell lymphoma (DLBCL) in 73.3% of cases, follicular lymphoma in 5.3%, mucosa-associated lymphoid tissue (MALT) in 10.7%, MALT/DLBCL in 2.6%, T-cell lymphoma in 2.6%, and Hodgkin’s lymphoma in 1.3%; percentages total 95.8% rather than 100% due to downward rounding.

In addition to rapid enlargement of a neck mass with compressive symptoms, findings that should raise suspicion of thyroid lymphoma include a history of Hashimoto’s thyroiditis and the ultrasound findings characterized by this study, Dr. Sharma said.

“Once you have that increased suspicion, you should move toward going to core biopsy rather than FNA to save the patient from having two diagnostic steps rather than one,” she concluded.

Dr. Sharma reported having no disclosures.

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