Clinicopathological features of 171 cases of primary thyroid lymphoma: a long‐term study involving 24 553 patients with Hashimoto’s disease

There are few large-scale reports of primary thyroid lymphoma (PTL). This study clinically and pathologically reviewed 171 patients with PTL and 24,553 patients with Hashimoto's disease at Ito Hospital between January 1990 and December 2004, to investigate the clinical features and the treatment outcomes of PTL. The median age of the patients with PTL was 67 years (range, 27-90 years). The pathological diagnosis of PTL patients included diffuse large B-cell lymphoma (DLBCL) (n=74), DLBCL with mucosa-associated lymphoid tissue (MALT) lymphoma (n=13), MALT lymphoma (n=80) and others (n=4). Of the 167 patients with B-cell lymphoma, treatment included combined modality therapy (CMT) (n=95), radiation therapy (RT) alone (n=60) and chemotherapy alone (n=6). Information on treatment was not available in six patients. Information on treatment response was available in 154 patients; 149 patients (97%) responded to treatment. According to the institutional treatment strategy of Ito Hospital, 45 of 54 patients with stage IE disease received RT alone, and 87 of 113 stage IIE patients received CMT. The 5-year overall survival rate was 85% (95% confidence interval, 79-91%). This study demonstrated that PTL showed good response to radiotherapy and chemotherapy and had a favourable prognosis.