Pituitary tumours: inflammatory and granulomatous expansive lesions of the pituitary.

Inflammatory and granulomatous diseases of the pituitary are rare causes of sellar masses. Lymphocytic hypophysitis is the most relevant of these disorders, and it is characterised by autoimmune pathogenesis with focal or diffuse inflammatory infiltration and varying degrees of pituitary gland destruction. Endocrine symptoms may include partial or total hypopituitarism, with adrenocorticotropic hormone (ACTH) deficiency being the earliest and most frequent alteration. Pituitary abscess is a rare but potentially life-threatening disease and, in 30-50% of patients, anterior pituitary hormone deficiencies or central diabetes insipidus (DI) at onset may be observed: the earliest manifestation being growth hormone deficiency (GHD), followed by follicle-stimulating hormone (FSH)/luteinising hormone (LH), thyroid-stimulating hormone (TSH) and ACTH deficiencies. Fungal infections of the pituitary are also very rare and include aspergillosis and coccidioidomycosis. Concerning pituitary involvement in systemic diseases, in sarcoidosis endocrine complications are rare, but the hypothalamus and pituitary are the glands most commonly affected. DI is reported in approximately 25-33 % of all neurosarcoidosis cases and is the most frequently observed endocrine disorder. Hyperprolactinaemia and anterior pituitary deficiencies may also occur. Rarely, partial or global anterior pituitary dysfunction may be present also in Wegener's granulomatosis, either at onset or in the course of the disease, resulting in deficiency of one or more of the pituitary axes. Other forms of granulomatous pituitary lesions include idiopathic giant cell granulomatous hypophysitis, Takayasu's disease, Cogan's syndrome and Crohn's disease. The hypotalamic-pituitary system is involved mainly in children with Langerhans' cells histiocytosis who develop DI, which is the most common endocrine manifestation. Anterior pituitary dysfunction is found more rarely and is almost invariably associated with DI. Pituitary involvement may also be observed in another form of systemic hystiocitosis, that is, Erdheim-Chester disease. Tuberculosis is a rare cause of hypophysitis, which may present with features of anterior pituitary dysfunction, such as hypopituitarism with hyperprolactinaemia. In conclusion, in patients with a sellar mass and unusual clinical presentation (DI, neurological symptoms), aggressiveness and onset and in the presence of systemic diseases, inflammatory and granulomatous pituitary lesions should be carefully considered in differential diagnosis.