Clinically functioning gonadotropin-secreting pituitary adenoma

SUMMARY: Gonadotroph adenomas are the most common type of nonfunctional pituitary adenomas. However, functioning gonadotroph adenomas causing clinical manifestations are rare. We present the case of a 42-year-old man with an incidental finding of a pituitary gland mass. A pituitary MRI revealed a 3 cm macroadenoma, and laboratory investigations revealed elevated follicle-stimulating hormone (FSH) and total testosterone levels. A diagnosis of functioning FSH-secreting pituitary adenoma was considered, with possible concomitant luteinizing hormone secretion, given the elevated testosterone, prompting further evaluation. Testicular ultrasound showed bilaterally enlarged testicles, and visual field testing revealed a monocular superior temporal defect. Transsphenoidal resection of pituitary adenoma was the treatment of choice. Histopathology assessment confirmed the diagnosis of gonadotroph-secreting adenoma, with positive staining for FSH. Within the 12-week postoperative period, FSH and testosterone levels normalized, and the patient experienced significant improvement in vision, along with the resolution of macroorchidism. While functional gonadotroph adenomas are rare, patients can present with a wide range of symptoms that are often unnoticeable due to their slow development. Careful evaluation can help guide multidisciplinary management to achieve full remission.

LEARNING POINTS: Endocrine evaluation is indicated in all cases of pituitary incidentalomas to determine functional status. Clinically functioning gonadotroph adenomas, while rare, pose a diagnostic challenge and require careful clinical evaluation. Transsphenoidal surgery is the mainstay of treatment of functioning gonadotroph adenomas, with the involvement of a multidisciplinary team to achieve desirable outcomes.