(12.09) Double Trouble: Extremely Rare Case of a Double Pituitary Adenoma

Double pituitary adenomas are very rarely reported in literature. We present a rare case of double pituitary adenoma with an unusual presentation.

Case(s) Description :

A 67-year-old male presented to the primary care clinic with symptoms of headache and blurred vision. As part of the work up, he underwent brain MRI which revealed an interesting finding of 2 separate pituitary adenomas. The left-sided adenoma was 10 x 11 x 7mm in size and right- sided adenoma was 6 x 3 x 5mm. The Endocrine Service was consulted. No symptoms suggestive of hormonal excess or deficiencies were reported. Complete pituitary work-up was done.

Laboratory values obtained were:

AM cortisol: 14.5 (5-22 ug/dL); ACTH: 33 (6-50 pg/mL); IGF-1: 75 (41-279 ng/mL); Free T4: 1.6 (0.8-2.2 ng/dL); Prolactin: 8.7 (3.7-17.9 ng/mL); Free testosterone: 55.1 (46-224 pg/mL); LH: 8.8 H (1.2-8.6 mIU/mL); FSH: 11.3 H (1.6-9.7 mIU/mL); Alpha subunit: 0.2 (0.1-0.5 ng/mL)

Most of the work-up was negative except for mildly elevated LH and FSH which could be secondary to age. Testosterone levels and alpha subunit levels were normal. Because he was also doing well clinically, and the optic chiasm was unaffected, the decision was made to monitor him periodically. A follow-up MRI 1 year later did not show any significant change in the size of either of the adenomas.

Discussion :

Double pituitary adenomas are very rare.  The prevalence of double or multiple pituitary adenomas has ranged between 1-9% in multiple autopsy studies. However, the prevalence is very low in published reports and surgical case series which indicates potential underdiagnosis of cases.

There are two types of presentations: Contiguous and clearly separated tumors. Most of the Contiguous type tumors are initially removed as one tumor and the presence of another adenoma is identified based on the histopathology report. This type is more common. In contrast, the clearly separated types can be identified by preoperative neuroimaging as in our case. This second presentation is very rarely reported.

Review of 9 different surgical case series showed the prevalence of multiple pituitary adenomas between 0.06%-2.6%. The most common abnormalities associated with these tumors were Acromegaly (50% of cases), and Cushing’s disease (22% of cases). A lack of at least one pituitary hormone deficiency or excess with double/multiple adenomas was very unusual.

Preoperatively diagnosed double pituitary adenoma based on MRI imaging is extremely rare. The unique finding in our case is the lack of any pituitary hormonal excess or deficiencies. The combination of macroadenoma and microadenoma in our patient is distinctive.