Acromegaly due to a growth hormone-releasing hormone-secreting intracranial gangliocytoma

In more than 95% of cases acromegaly is due to GH hypersecretion by a pituitary adenoma. GHRH hypersecretion accounts for about 0.5% of cases of acromegaly. Intracranial GHRH-secreting tumors are extremely rare and only a few well-documented cases have been reported. The clinical features of acromegaly due to intracranial GHRH-secreting tumor are indistinguishable from those of other patients with "classical acromegaly". In cases of intrasellar gangliocytomas, not even radiological findings help to make the correct diagnosis, which can only be made with the hystological study. We present the case of a woman with acromegaly; the magnetic resonance demonstrated a 2x1.8x1.2 cm mass in the jugum sphenoidalis region, associated with a partial empty sella. There was a partial response to high-dose lanreotide therapy, so surgical treatment was decided, although only part of the tumor could be removed. Histopathological diagnosis was consistent with gangliocytoma, and immunostaining in the ganglionic cells was positive for GHRH. After surgery, hormone hypersecretion persisted, so medical treatment was reintroduced. In summary, we report a well-documented case of an intracranial GHRH-secreting gangliocytoma, an exceedingly rare cause of acromegaly. Clinical and biochemical data did not allow to make the correct diagnosis, which was only made on the pathological study. This case underscores that acromegaly can be due to causes other than a GH-secreting adenoma, and underlines that finding an image not typical of a pituitary adenoma should raise the suspicion that an unusual cause subsides the acromegaly.