SAT-098 - Pituitary Stalk Duplication in A Patient with A Pituitary Mass: An Unusual Imaging Finding

Background: Isolated pituitary stalk duplication with a single pituitary gland is extremely rare. We present a case of duplicate infundibulum in a patient being evaluated for a pituitary mass.
Clinical

Case: A 67-year-old female with a history of primary hypothyroidism and migraines presented to the endocrinology clinic after a hypoenhancing lesion was noted on imaging. An initial brain magnetic resonance imaging (MRI) scan was performed a year prior to her endocrine evaluation as part of the assessment for her migraines. This revealed a focus of decreased contrast uptake in the posterior aspect of the gland. A dedicated pituitary MRI, performed two months before her clinic visit, demonstrated an unchanged 7 mm hypoenhancing lesion in the posterior aspect of the pituitary gland. There was no mass effect on the surrounding anatomic structures, suprasellar extension, or threat to the optic chiasm. Interestingly, a separate abnormality to the pituitary stalk was also seen, with the infundibulum appearing to be duplicated. Examination showed full visual fields and no stigmata of endocrine disease. Hormonal testing revealed no abnormalities, except for slightly decreased prolactin level (2.3 ng/ml, reference range: 4.8-23.3). The sellar lesion was considered a non-functional microadenoma or a Rathke’s cleft cyst. A follow-up MRI scan 9 months later showed a stable pituitary lesion; the duplicate stalk was again noted.

Discussion: Pituitary stalk duplication is an extremely rare abnormality, often associated with duplication of the pituitary gland itself and also other neurologic or craniofacial defects. The etiology is not clear, but genetic causes affecting embryogenesis have been suggested as major contributors. The diagnosis is typically incidental on MRI. Hormonal deficits, particularly growth hormone deficiency, can be seen, and patients should be screened for pituitary dysfunction. Our patient did not have a duplicated gland or other anatomical abnormalities, and endocrine function was intact, save for a mildly low prolactin level of uncertain origin and significance. A small pituitary mass was identified at the same time the duplicated stalk was revealed. Cases of infundibulum duplication in association with sellar tumors, including an adenoma and a dermoid, have been reported, but no causal relation has been established.

References:
(1) Sethi HS, et al. Finding its place on the spectrum of pituitary duplication disorders, duplication of pituitary stalk: A case report with brief review of literature. Neuroradiol J. 2024;37(3):357-360.
(2) Sravya SL, et al. Pituitary Stalk Duplication: A Radiological Surprise in a Child With Short Stature. AACE Clin Case Rep. 2023;9(5):166-169.
(3) Petridis AK, Barth H. Pituitary stalk duplication in ventral-dorsal direction in a patient with pituitary gland adenoma and aqueductal stenosis. Clin Anat. 2010;23(8):879-80.

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