Summary

A 57-year-old woman was admitted to the emergency department, presenting with episodes of altered consciousness and behaviour which, upon further examination, were linked to periods of recurrent hypoglycaemia. Imaging revealed a large mass in the right thoracic cavity while blood analysis demonstrated diminished C-peptide, (pro-)insulin, insulin-like growth factor 1 (IGF-I) and IGF binding protein 3 levels. Based on these findings, an IGF-II secreting tumour was suspected. Before the excision of the tumour, euglycaemia could only be achieved by means of intravenous glucose administration and the use of oral corticosteroids. Anatomopathologically the diagnosis of a solitary fibrous tumour (SFT) was confirmed. Immunoblot analysis on the serum revealed elevated ‘big’-IGF-II levels, confirming our initial diagnosis of Doege–Potter syndrome in SFT.