In this series of 224 tumours, we identified six factors that seem to predict PC patient outcome: age over 56 years at the time of diagnosis, tumour size over 2.5 cm, atypical histology, Ki-67 proliferation index higher than 2.5%, hilar/mediastinal lymph node involvement at the time of diagnosis, and the presence of metastatic disease. Here, MKI67 is linked to pachyonychia congenita.