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.
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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.
Associations
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autoimmune conditions such as
-
immune checkpoint inhibitors
more common with CTLA4 inhibitors (e.g. ipilimumab) than PD-1 or PD-L1 inhibitors 9,10
Clinical presentation
Clinical presentation is varied depending on the part of the pituitary affected and the size of the lesion. Lymphocytic hypophysitis can thus be classified as:
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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
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.
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.
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T1
affected area is isointense with slight signal heterogeneity
normal posterior pituitary bright spot may be absent 8
-
T1 C+ (Gd)
can variably enhance, usually homogeneously 7
dural enhancement may be present 8
infundibulum may be thickened 8
-
T2
hypointensity in parasellar region (parasellar dark T2 sign) can be present and may be useful in differentiating from a pituitary adenoma 4
Treatment and prognosis
Lymphocytic hypophysitis is usually self-limiting and spontaneous recovery can occur. Corticosteroids are sometimes given and deficient hormones can be replaced 8. In patients on immune checkpoint inhibitors, consideration should be given towards stopping this therapy, either temporarily or permanently 10.
Differential diagnosis
The differential diagnosis is primarily that of other pituitary region masses. Considerations include:
-
macroadenomas are expected to enlarge the sella turcica
craniopharyngioma (papillary type)
-
suprasellar meningioma
dural-based
usually follows the cerebral cortex intensity
granulomatous hypophysitis (idiopathic or secondary to systemic illness e.g. sarcoidosis, syphilis, and tuberculosis)
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