1. Department of Endocrinology, Diabetes and Metabolism, Endocrine Tumour Centre at WTZ and Member of ENDO‐ERN, University Hospital Essen University Duisburg‐Essen Essen Germany
2. Department of Internal Medicine III, University Hospital Carl Gustav Carus Technische Universität Dresden Dresden Germany
3. Division of Endocrine Surgery, Endocrine Tumour Centre at WTZ and Member of ENDO‐ERN, University Hospital Essen University Duisburg‐Essen Essen Germany
4. Institute of Pathology, Endocrine Tumour Centre at WTZ and Member of ENDO‐ERN, University Hospital Essen University Duisburg‐Essen Essen Germany