Lymphocytic Hypophysitis

LSU Medical Center

Greg Dowd, MD and Deepak Awasthi, MD
Department of Neurosurgery; LSU Medical Center; New Orleans, LA

Introduction:
Lymphocytic hypophysitis (LH) is an important cause of pituitary dysfunction in the young female. Multiple reports in the last 15 years have helped to clarify this disorder as an auto immune inflammation of the pituitary gland. This process can lead to both endocrine dysfunction and/ or gland enlargement with compression of visual pathway structures. As treatment strategies for this condition differ from other lesions of the pituitary, recognition of this diagnosis is crucial.

The pathology of LH was first described in 1962 in a young postpartal female who died of shock following an appendectomy (7). She was found to have marked adrenal atrophy in addition to fibrosis and lymphocytic invasion of her piuitary gland. Subsequent autopsy reports in young postpartum females followed suggesting a dismal course for lymphocytic hypophysitis. However, in 1980 an antemortem diagnosis and successful outcome was documented in a patient that under went a trans- sphenoidal resection of a suspected pituitary tumor (9). Since this time, several indicators suggest thst this rarely diagnosed condition is probably much more common than previously suspected.

LSU Experience:
During the period 1993-6, three patients with lymphocytic hypophysitis presented to the neurosurgical service. All three patients were young females in the early post partum period with headaches and visual field deficits. Table 1 provides a summary of their clinical picture at presentation.

TABLE 1
Lymphocytic Hypophysitis
LSU Experience 1993-1996

TSH: Thyroid stimulating hormone
FTI: Free Thyroid Index
PRL: Prolactin
ext: extension

Case History:
A.H. is a 26 yo black female who was previously healthy and five months postpartum from a normal vaginal delivery. She had complained of headaches since delivery and persistent amenorrhea despite bottle feeding. She noticed a right temporal visual field deficit one month prior to neurosurgical evaluation. An MRI (Figure 1) demonstrated a 2.0 x 2.5 cm lesion with suprasellar extension and chiasmal compression. This had diffuse enhancement with contrast, including the infundibular area.

The patient underwent near total hypophysectomy via the trans-sphenoidal route with decompression of the chiasm. The pituitary tissue was found to be brownish and fibrous. Microscopic evaluation showed fibrous inflammatory tissue surrounding clumps of pituitary tissue. A decadron stress dose and taper over a ten day period was also given. Post-operatively, the patient had transient diabetes insipidus necessitating DDAVP for four days and had resolution of her headaches and visual field deficit. A follow up MRI done two months later showed a normal pituitary gland without enhancement and a decompressed optic chiasm.

Discussion:
The cases presented here serve to illuminate and confirm the most common presentation of lymphocytic hypophysitis. Although described in both sexes (1) and in all age groups from adolescence until old age, young females either during pregnancy or immediately post partum comprise the bulk of the patients.

Pathophysiology:
The occurrence of pituitary inflammation associated with pregnancy is felt to be secondary to the involution of the pituitary gland that takes place during this time (4,7). Under the influence of estrogen during pregnancy, the pituitary gland increases in size up to 400% (6). This rapidly returns to baseline following parturition. Serologic examination of women one week following normal delivery demonstrated that 18% developed anti- pituitary antibodies (5). It was noted that those with antibodies present had a much higher incidence of pituitary insufficiency. This suggests that pregnancy induced reaction against the pituitary gland may affect a potentially large group of women with a range of pathologic changes. It is entirely possible that those women diagnosed with lymphocytic hypophysitis due to a visual defect or gross hormonal change represent only the tip of the iceberg.

In women with the appropriate immune background, an auto immune response is generated. Amongst one group of LH patients, a 24% prevalence of other auto immune disorders was identified (11). Thyroiditis was the most common disorder amongst this group. Several of the cases of LH have not been associated with pregnancy but their was an history of an antecedent viral illness. Possibly an altered immune reaction to the viral antigens cross reacted with the pituitary tissue. This suggests that lymphocytic hypophysitis may be the final common pathway for several combinations of genetic backgrounds and antigen combinations.

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