Physical Address

304 North Cardinal St.
Dorchester Center, MA 02124

Pituitary Macroadenoma


KEY FACTS

Terminology

  • Benign neoplasm of adenohypophysis

Imaging

  • Upward extension of macroadenoma = most common suprasellar mass in adults

  • Best imaging technique

    • MR with sagittal/coronal thin-section imaging through sella + T1 C+ with FS

  • Sellar mass without separate identifiable pituitary gland = macroadenoma

  • Mass is pituitary gland

  • Usually isointense with gray matter

  • Enhance strongly, often heterogeneously

  • Cavernous sinus invasion difficult to determine

Top Differential Diagnoses

  • Pituitary hyperplasia

  • Saccular aneurysm

  • Meningioma (diaphragma sellae)

  • Metastasis

  • Lymphocytic hypophysitis

  • Craniopharyngioma

Pathology

  • WHO grade I

  • MIB-1 > 1% suggests early recurrence, rapid regrowth

  • Invasive adenoma > > pituitary carcinoma (rare)

Clinical Issues

  • Beware: Adenoma-like mass in adolescent/prepubescent boys may represent hyperplasia secondary to end-organ failure

  • Prolactin-secreting adenoma is most common functional adenoma

Diagnostic Checklist

  • No matter how aggressive/invasive it looks, pituitary tumors are almost never malignant

Coronal graphic shows a snowman-shaped or “figure 8” sellar/suprasellar mass
. Small foci of hemorrhage
and cystic change
are present within the lesion. The pituitary gland cannot be identified separate from the mass; indeed, the gland is the mass.

T1 C+ MR in a 68-year-old man with elevated prolactin shows a classic “figure 8” or “snowman” appearance of the pituitary macroadenoma
. There is mild displacement of the optic chiasm
. The pituitary gland cannot be separated from the mass.

Coronal T2 MR in a 64-year-old woman with visual changes shows a large adenoma
with cystic change
filling the sella and suprasellar region. Note the patent cavernous carotid artery
.

Coronal T1 C+ MR in same patient shows heterogeneous enhancement
of the macroadenoma. There is tumor lateral to the cavernous carotid artery representing cavernous sinus invasion
and nonfunctional adenoma found at resection. The cavernous sinus disease was treated with radiation therapy.

TERMINOLOGY

Synonyms

  • Macroadenoma, pituitary adenoma, prolactinoma

Definitions

  • Benign neoplasm of adenohypophysis

IMAGING

General Features

  • Best diagnostic clue

    • Sellar mass without separate identifiable pituitary gland; mass is gland

  • Location

    • Most common: Intra- or combined intra-/suprasellar

      • –

        Upward extension of macroadenoma = most common suprasellar mass in adults

    • Uncommon: Giant adenoma

      • –

        May invade skull base, extend into anterior/middle/posterior fossae

      • –

        Can mimic metastasis or other malignant neoplasm

    • Rare: “Ectopic” pituitary adenoma

      • –

        Sphenoid sinus most common

      • –

        Cavernous sinus, clivus, 3rd ventricle, infundibulum

  • Size

    • > 10 mm

    • “Giant”: > 4 cm in diameter (< 0.5%)

  • Morphology

    • Most common: “Figure 8” or “snowman”

      • –

        Indentation: Dural constriction caused by diaphragma sellae

    • Less common: Multilobulated margins

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here

Related Posts