Diagnosis and treatment of primary thyroid lymphoma from a surgical perspective: a multi-institutional study

Purpose Surgery of primary thyroid lymphoma (PTL) has been mostly limited to diagnostic work-up. This study aimed to further study its potential role. Methods This was a retrospective study from a multi-institutional registry of PTL patients. Clinical, diagnostic work-up (fine needle aspiration, FNA; core needle biopsy, CoreNB), contribution of surgery (open surgical biopsy, OpenSB; thyroidectomy), histology subtype, and outcome data were evaluated. Results Some 54 patients were studied. Diagnostic work-up included FNA in 47 patients, CoreNB in 11, and OpenSB in 21. CoreNB yielded the best sensitivity (90.9%). Thyroidectomy was performed in 14 patients with other diagnosis (incidental PTL), in 4 for diagnosis and in 4 for elective treatment of PTL. Incidental PTL was associated with not performed FNA nor CoreNB (OR 52.5; P = 0.008), mucosa-associated lymphoid tissue (MALT) subtype (OR 24.3; P = 0.012), and Hashimoto’s thyroiditis (OR 11.1; P = 0.032). Lymphoma-related death (10 cases) mostly occurred within the first year after diagnosis and was associated with diffuse large B-cell (DLBC) subtype (OR 10.3; P = 0.018) and older patients (OR 1.08 for every 1-year increase; P = 0.010). There was a trend towards lower mortality rate in patients receiving thyroidectomy (2/22 versus 8/32, P = 0.172). Conclusion Incidental PTL accounts for most of thyroid surgery cases and are associated with incomplete diagnostic work-up, Hashimoto’s thyroiditis and MALT subtype. CoreNB appears to be the best tool for diagnosis. Most of PTL deaths occurred during the first year after diagnosis and mostly related to systemic treatment. Age and DLBC subtype are poor prognostic factors.