Primary thyroid lymphoma: a case series

Primary Thyroid Lymphoma (PTL) is defined as lymphoma involving the thyroid gland alone or the thyroid gland and adjacent neck lymph nodes without contiguous spread or distant metastases at the time of diagnosis. Most thyroid lymphomas are B cell lymphomas, and 98% of all PTL cases are non-Hodgkin's lymphoma. It is a rare disease accounting for around 5% of the thyroid neoplasms and 2% of extranodal lymphomas. If properly diagnosed and treated, the prognosis is favorable.

Five cases (three men and two women) of PTL were diagnosed and treated in our institute between January 2005 and September 2019. These are 5 cases of Caucasian origin. The mean age was 76.2 (range: 63-95 years); one patient had associated hypothyroid. One patient had a medical history of breast cancer; one was hypothyroid, and four were euthyroid at the diagnosis. In 4 of these patients, PTL started with compressive symptoms. No patients underwent fine needle aspiration cytology (FNAC) or biopsy for the diagnostic only. In sonography, two cases showed bilateral nodules with goiter; in the three cases it showed nodules in the lobe and isthmus. Technetium-99m scintigraphy was performed on only two patients. Bone Marrow Biopsy (BMB) showed normal cellularity in 4 cases and only one case showed tumor cells. LDH levels were increased in all cases. The extension was evaluated in all patients with cervical and thoracic CT scans, Bone Marrow Biopsy (BMB), beta-2 microglobulin, and serum lactate dehydrogenase (LDH) levels. Three cases were staged as IE and two cases as IIE. Three patients underwent total thyroidectomy; two of them underwent cervical lymph node dissection. Two patients underwent lobectomy. All were diagnosed with lymphoma postoperatively and all were diffuse large B cell lymphoma (DLBCL). One patient completed treatment with R-CHOP (Rituximab, Cyclophosphamide, Doxorubicin, Vincristine, and Prednisone), and two cases received adjuvant chemo-radiotherapy (30 Gy). Two patients died immediately after surgery.

PTL is a rare disease whose diagnosis should be considered in cases of rapidly growing goitres. Timely needle biopsy in suspected cases can avoid unnecessary surgery. Systemic treatment is required, depending on the stage of the tumour.