Orpha code: 99408

Rare pituitary and hypothalamic tumors require highly specialized neurosurgery and other interventions (medication, radiotherapy), and recent developments focus on the genetics and tumor biological characteristics resulting in different prognosis and therapeutic efficacy. This subtheme includes different types of pituitary adenomas [non-functioning adenomas, prolactinomas, growth hormone producing adenomas (acromegaly), ACTH producing adenomas (Cushing’s disease), TSH producing adenomas, LH/FSH producing adenomas, mixed tumors]. It also includes other masses in the sellar region, such as Ratke’s cleft cysts and craniopharyngeoma. Several subsets of ultrarare conditions can be identified, for example genetic causes e.g. AIP mutations causing familial isolated pituitary adenoma.

Congenital Hypopituitarism

Orpha code: 101957

Congenital hypopituitarism results from insults in the developmental process of the pituitary that can result in the loss or reduction of pituitary hormone-secreting cells, with phenotypes ranging from multiple pituitary hormone deficiencies [combined/multiple pituitary hormone deficiency (CPHD/MPHD)] to deficiencies in single hormones only, the most common isolated hormone deficiency being attributed to growth hormone. The condition can be life-threatening or life-limiting, and needs careful and expert management. Given its midline location, and that the pituitary gland is derived from the same region of the neural plate as the hypothalamus, optic nerves and forebrain as described above, hypopituitarism is often associated with craniofacial/eye/midline disorders, also affecting these related structures. Such disorders are characteristically heterogeneous but range from incompatibility with life, to holoprosencephaly (HPE) and cleft palate and septo-optic dysplasia (SOD), all of which are associated with complex morbidity including autism, learning difficulties and obesity. Many genes have been (and are being) discovered and expertise sharing to improve knowledge of genotype-phenotype will help to improve patient care.

Acquired Hypopituitarism

Orpha code: 95502

Acquired hypopituitarism usually results from other pituitary conditions or the treatment of hypothalamo-pituiary tumours with radiotherapy and surgery, however, there are several other causes, such as vascular (Sheehan’s syndrome), trauma (traumatic brain injury), infective (Group B strep, tuberculosis), systemic inflammatory or infiltratative diseases (sarcoidosis, histiocytosis, hypophysitis) and new drugs.