Laboratory and Imaging Studies

The results of initial endocrine testing confirmed the diagnosis of acromegaly ( Table 1 ; please click on the link "Tables" in the table of contents section on the upper left-hand side of the page). In addition, tests revealed a markedly elevated prolactin level and central hypogonadism.

A plain radiograph of the skull (Figure 3) showed an enlarged sella turcica. MRI of the pituitary (Figures 4a and 4b) demonstrated a large mass occupying the sella turcica and clivus, with extension into the suprasellar space, right middle cranial fossa, and sphenoidal sinus.

Plain skull radiograph. Note marked enlargement of the sella, measuring approximately 5 cm, with complete destruction of the dorsum and floor, possibly extending posteriorly to the clivus, with minimal residual of the tip of the posterior clinoid process compatible with a large destructive lesion.

Pituitary MRI. A 5-cm lesion centered in the region of the clivus and sella, eroding the clivus and displacing the pons and mid-brain dorsally. It extends below the sphenoid sinus, into the suprasellar cistern, the right cavernous sinus, and the right middle cranial fossa, displacing the right temporal lobe.

Pituitary MRI. A 5-cm lesion centered in the region of the clivus and sella, eroding the clivus and displacing the pons and mid-brain dorsally. It extends below the sphenoid sinus, into the suprasellar cistern, the right cavernous sinus, and the right middle cranial fossa, displacing the right temporal lobe.

What is the significance of the elevated prolactin level?

  1. Prolactin levels are frequently elevated in patients with pituitary adenomas. This elevation may be due to compression of the pituitary stalk by a large tumor. Such compression would disrupt dopaminergic nerve axons that normally transmit inhibitory impulses to the pituitary lactotrophs, leading to disinhibition of prolactin synthesis and secretion. If stalk compression is the cause, serum prolactin levels are typically only modestly elevated (< 200 ng/mL). Prolactin levels greater than 200 ng/mL are almost always indicative of an adenoma that produces and secretes both GH and prolactin. Pituitary adenomas producing both GH and prolactin have been described in approximately 25% of cases. Their frequent occurrence is likely related to the shared ontogeny (evolution from a common ancestral gene) of the 2 hormones.

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What is the treatment of choice for this patient?

  1. The therapeutic goal in patients with acromegaly is to reduce tumor size as much as possible and to normalize serum concentrations of both GH and IGF-1. Current therapeutic strategies for acromegaly include transsphenoidal surgery, radiation therapy, radiosurgery, and medical management with somatostatin analogs or dopamine agonists. Resectability is the most important factor when deciding the initial treatment modality. Microadenomas and macroadenomas deemed surgically resectable should be removed.

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