• This Clinical Practice Guideline provides key recommendations for managing rare endocrine tumours. • Neuroendocrine neoplasms of different origins, parathyroid carcinoma and intrathyroid thymic neoplasms are included. • The guideline covers clinical imaging and pathological diagnosis, staging and risk assessment, treatment and follow-up. • The authors comprise a multidisciplinary group of experts from different institutions and countries in Europe. • Recommendations are based on available scientific data and the authors’ collective expert opinion.