The significance of MALT histology in thyroid lymphoma: a review of patients from the BNLI and Royal Marsden Hospital.

Data from a series of 45 patients with Stage I and II non-Hodgkin's lymphoma (NHL) of the thyroid gland were analysed retrospectively to determine the incidence and prognostic significance of histopathological features of tumour origin from mucosa associated lymphoid tissue (MALT). The overall 5- and 10-year cause specific survival from NHL for the series was 79%. Evidence of tumour origin from MALT was the only significant prognostic factor for overall survival identified by multivariate analysis of the series (P < 0.01). A total of 31 (69%) tumours showed such evidence, the cause specific patient survival from NHL at 5 and 10 years being 90% compared with only 55% at 5 years for the 14 patients without such evidence. For patients given initial treatment with radiotherapy alone, those with evidence of tumour origin from MALT had a relatively low relapse rate and a relatively high success rate from salvage therapy, compared with a relatively high relapse rate and negligible success from salvage therapy in those without evidence of such tumour origin.