Thymic epithelial tumours in Iceland: incidence and histopathology, a population-based study

Abstract

The objective of this study was to re-examine histologically and restage thymic epithelial tumours during a 25-year period and to correlate clinical and follow-up data. We utilized centralized registries in Iceland to establish a true nationwide incidence rate, previously unreported. A retrospective whole population study was carried out by including all patients diagnosed with a thymic epithelial tumour in Iceland between 1 January 1984 and 30 April 2010. Medical records were reviewed and presenting symptoms, diagnostic procedures and surgical outcome tabulated. The histology of all cases was reclassified according to the 2004 World Health Organization classification (A-TC). The Masaoka system was used for tumour staging. Median follow-up was 67 months. A total of 19 patients were identified, 11 men (58%) and 8 women, with mean age at presentation of 63 years (31-87 years). The age-standardized incidence rate (ASR) was 0.3 and 0.2/100 000/year for men and women, respectively. Types B2 (n = 5) and A (n = 5) were the most common histological subtypes. Half of the patients had local symptoms, and eight were diagnosed incidentally. Of 19 patients, 11 underwent resection of the tumour through median sternotomy. Five-year overall survival was 53%. All four patients with thymic carcinoma (TC) died of disease within 2 years of diagnosis. For the other 15 patients, no recurrences were reported. Thymic tumours are rare in Iceland with an ASR (w) of 0.28 per 100 000 a year. To our knowledge, these are the first nationwide ASR (w) figures reported. The prognosis for most thymic epithelial cell tumours is excellent. However, TCs have a dismal long-term survival.