Objective:To report a rare case of incipient granulomatous hypophysitis presenting by atypical trigemino-autonomic cephalalgia (TAC) and Horner syndrome.Methods:The patient was investigated with repeated brain MRI, CSF examination, thoracic CT, Doppler and duplex ultrasound of the cerebral arteries, and extensive serologic screening for endocrine and autoimmune markers. Written informed consent was obtained from the patient for access to clinical files for research purposes and for publication.Results:We present a middle-aged woman with a history of an autoimmune pancreatitis type 2 who had therapy-refractory TAC with Horner syndrome. Initial cerebral MRI showed only indistinct and unspecific signs of a pathologic process. A biopsy revealed a granulomatous hypophysitis. The symptoms disappeared after transsphenoidal subtotal resection of the pituitary mass and anti-inflammatory therapy.Conclusions:This case elucidates that inflammatory pituitary diseases must be taken into account in case of atypical and refractory TAC, especially in patients with a history of autoimmune diseases. To our knowledge, the association between TAC accompanied by Horner syndrome and hypophysitis has not yet been described before.