Autoimmunhypophysitis

Lymphocytic hypophysitis is an uncommon non-neoplastic inflammatory condition that affects the pituitary gland. It is closely related to other inflammatory conditions in the region, namely orbital pseudotumor and Tolosa-Hunt syndrome.

Epidemiology

Lymphocytic hypophysitis is seen most frequently in women, with a F:M of ~ 9:1, and often in the postpartum period or the third trimester of pregnancy.

Clinical presentation

Clinical presentation is varied depends on the part of the pituitary affected and the size of the lesion. Lymphocytic hypophysitis can thus be classified as:

• anterior pituitary: lymphocytic adenohypophysitis
  • most common
  • mimics a pituitary adenoma
  • endocrine hormone deficits are common, including hypopituitarism
  • mass effects on adjacent structures (e.g. optic chiasm)
• posterior pituitary: lymphocytic infundibular neurohypophysitis
  • rare
  • diabetes insipidus
• both anterior and posterior pituitary: lymphocytic infundibular panhypophysitis

Pathology

It is characterized by infiltration of the pituitary stalk with lymphocytes, as the name would suggest. Importantly, there is a paucity of plasma cells or granulomas, differentiating it from IgG4-related hypophysitis and granulomatous hypophysitis (e.g. due to neurosarcoidosis) respectively.

Associations

• autoimmune conditions such as
  • autoimmune thyroiditis
  • pernicious anemia
• ipilimumab: monoclonal antibody drug

Radiographic features

CT

Coronal CT and multiplanar reconstructions can visualize the pituitary region reasonably well. Lymphocytic hypophysitis appears as an enhancing soft tissue mass involving the pituitary and extending into the suprasellar region.

MRI

MRI, as is the case with other pituitary lesions, is the best modality for assessing this condition which appears as a pituitary region mass.

• T1
  • affected area is isointense with slight signal heterogeneity
  • normal posterior pituitary bright spot may be absent
• T1 C+ (Gd)
  • can variably enhance, usually homogeneously
  • dural enhancement may be present
  • infundibulum may be thickened
• T2
  • hypointensity in parasellar region can be present and may be useful in differentiating from a pituitary adenoma

Treatment and prognosis

Lymphocytic hypophysitis is usually self-limiting and spontaneous recovery can occur. Corticosteroids are sometimes given and deficient hormones can be replaced .

Differential diagnosis

The differential diagnosis is primarily that of other pituitary region masses. Considerations include:

• pituitary adenoma
  • macroadenomas are expected to enlarge the sella turcica 
• craniopharyngioma (papillary type)
• suprasellar meningioma
  • dural-based
  • usually follows the cerebral cortex intensity
• pituitary metastasis
• Langerhans cell histiocytosis (LCH)
• IgG4-related hypophysitis
• granulomatous hypophysitis (idiopathic or secondary to systemic illness e.g. sarcoidosis, syphilis, and tuberculosis)
• xanthomatous hypophysitis
• necrotizing hypophysitis

Siehe auch:

• Raumforderungen des Clivus
• Tumoren der Hypophysenregion
• Kraniopharyngeom
• Hypophysenadenom
• pituitary metastasis
• Hypophysitis
• Immun-Checkpoint-Inhibitor-Therapie

und weiter:

• verdickter Hypophysenstiel
• Makroadenom Hypophyse
• Neurosarkoidose
• Pituitary MRI (an approach)
• metastases to the pituitary gland
• solid and enhancing pituitary region mass
• purely intrasellar pituitary mass
• Pituizytom
• Autoimmunerkrankungen
• Lymphom der Hypophyse