Granulomatosis with polyangiitis (GPA), previously known as Wegeners granulomatosis, is a rare heterogeneous vasculitic disease characterised by necrotising granulomatous inflammation typically affecting lungs and kidneys. GPA affecting pituitary is rare and usually results in posterior pituitary involvement causing diabetes insipidus. We describe a case of GPA, presenting with pituitary involvement causing headaches and anterior pituitary hormone deficiencies.
Middle-aged lady presented with 7 weeks of worsening retro-orbital headaches. Initial investigations included MRI head which showed a sellar lesion, suggestive of inflammatory conditions like sarcoid or metastasis. She had no features of pituitary hormone deficiencies, systemic vasculitides, or other system involvement. Tests confirmed hypopituitarism involving gonadal and thyroid axes. Empirical treatment with intravenous methylprednisolone, for possible sarcoid, improved symptoms. A staging CT scan showed localised pulmonary consolidation. She was discharged on hydrocortisone and thyroxine replacement with plans for further assessment. She re-presented 2 weeks later with dyspnoea; the pulmonary lesion had significantly enlarged. A diagnostic lobectomy revealed extensive suppurative necrotising granulomatosis on histology. Vasculitic screen revealed anti-neutrophil cytoplasmic antibody proteinase 3 (cANCA-PR3), consistent with GPA. Serum ACE was normal. Pulse cyclophosphamide therapy and maintenance with azathioprine/prednisolone resulted in clinical improvement. A repeat pituitary MRI scan, seven months later, showed shrinkage of the pituitary lesion.
The pathophysiology of pituitary GPA is described as granulomatous invasion from nasal or paranasal lesions, in-situ granuloma formation, and/or inflammation of the pituitary vasculature. This case is unusual in its involvement of pituitary gland in the initial presentation and absence of the usually described diabetes insipidus. The case highlights the importance of assessing the pituitary in granulomatous diseases, especially GPA. Early identification of pituitary GPA and replacement of deficient pituitary hormones is crucial in the often catastrophic disease course. Appropriate Immunomodulatory therapy can prevent the otherwise inevitable destruction of the pituitary gland.