Fig. 1

Time to metastasis from the primary diagnosis. a M0 patients (n = 34), b all patients with or without pulmonary metastases (n = 48). a Twenty-eight patients (82.4%) developed metastasis within 4 years and 31 patients (91.2%) within 8 years. Only three patients (8.8%) developed metastasis after 8 years of follow-up. b “with lung metastasis” means the presence of lung metastasis with or without metastasis in another location, and “without lung metastasis” means absence of lung metastasis at the initial diagnosis of metastasis. In patients “with lung metastases”, five out of 9 patients (55.6%) had metastasis at the initial diagnosis of primary MLS, and all patients were diagnosed to have metastasis within 2 years, which was significantly shorter than in patients “without lung metastases” (15.3 months; p = 0.007)