Endocrine Abstracts

Background: Gonadotroph adenomas are the most common non-functioning pituitary adenomas in adult^{1, 2}. However, functioning gonadotrophinomas are rare. Here, we describe an unusual presentation of concurrent acromegaly and functioning FSHoma (FSH-secreting pituitary adenoma).

A 39-year-old man presented with a vague visual disturbance to the optometrist and a bitemporal hemianopia was detected.

Further questioning elicited increase in shoe size with no significant history of sweating, headache and change in hand size.

Physical examination was notable for features of acromegaly (prominent eyebrows, prognathism, large hands and feet) and bilateral testicular enlargement.

Endocrine profiling confirmed acromegaly on OGTT- oral glucose tolerance test (non-suppressed nadir GH level of 1.2 μg/l with basal GH level of 1.5 μg/l). IGF 1 level was elevated at 64 (9.5–45) nmol/l. There was significantly elevated FSH level of 107.2 (1–10.1) U/l with LH 1.2 (1.5–6.3) U/l and testosterone 9.3 (8–29) nmol/l. The rest of pituitary profiling was normal: Prolactin 370 (45–375) mU/l, TSH 0.65 (0.35–5.5) mU/l, FT₄ 12.3 (10–19.8) pmol/l, normal short synacthen test.

US testes confirmed bilateral testicular enlargement: left testis measuring 46 cc and right testis measuring 50 c with no neoplastic changes.

MRI pituitary demonstrated a large pituitary macroadenoma 3.5×2.8 cm, with the expansion of pituitary fossa, compressing optic chaism and extending into left cavernous sinus.

Subsequently transsphenoidal hypophysectomy was performed. Histology confirmed chromophob pituitary adenoma. Immunohistochemistry showed FSH-immunoreactive adenoma with negative GH staining.

Literature analysis revealed very rare synchronous presentation of acromegaly and FSH-secreting pituitary adenoma³. Concurrent GH and prolactin secretion is more common.

References: 1. Chanson P & Brochier S. Non-functioning pituitary adenomas. J Endocrinol Invest. 2005 28 (11 Suppl International) 93–9.

2. Tamiya H, Fukuhara N, Yoshida N, Suzuki H, Takeshita A, Inoshita N, et al. A silent follicle-stimulating hormone-producing pituitary adenoma in a teenage male. Endocr Pathol. 2011 22 (4) 212–7.

3. Kontogeorgos G, Scheithauer BW, Horvath E, ovacs K, Lloyd RV, Smyth HS, et al. Double adenomas of the pituitary: a clinicopathological study of 11 tumors. Neurosurgery. 1992 31 (5) 840–9 (discussion 9).