PANCREAS / SPLEEN / ADRENAL GLANDS

Very rare w prevalence approx 1/1,000,000. Highly aggressive w/ poor prognosis
~66% are functional producing a disordered array of hormones that may manifest as Cushing syndrome, hyperaldosteronism, and virilization.

Imaging:

IMAGING FEATURES

CANNOT be distinguished from other tumors by imaging alone. Need clinical hx and lab values (urinary and plasma fractionated metanephrines)
Highly vascular and prone to hemorrhage

US: hypoechoic suprarenal lesion +/- cystic change
NECT: >10 HU
CECT:
- Delayed washout kinetics typically similar to adrenal CA and mets, but rapid washout like adenoma is possible.
- Heterogeneous enhancement 2/2 necrosis, cystic degeneration, hemorrhage.
MR: Variable T1/T2 signal 2/2 hemorrhage, cystic degeneration, necrosis; T2 light bulb hyperintensity
Ga-68 DOTATATE: ectopic, recurrent and metastatic tumors. (see below)

PHEOCHROMOCYTOMA

PHEOCHROMOCYTOMA STATDx

Intra-adrenal paraganglioma; neuroendocrine tumor that typicaly originates from the adrenal medulla.

Composed of chromaffin cells that secrete catecholamines and cause uncontrolled secondary HTN and episodic headaches/diaphoresis.
Hereditary type: small bilateral adrenal lesions in young patient.
Syndromes:
- MEN2A/B: b/l intraadrenal pheos
- NF1
- vHL
- Carney's triad (gastric leiomyosarcoma, pulmonary chondroma, paraganglioma)
- Hereditary paraganglioma-pheochromocytoma syndrome: SDHD gene mutation.
Sporadic type: large > 3 cm, unilateral mass in older pt
90% arise in adrenal, 90% unilateral, ~90% are benign
- Called paraganglioma when tumor arises in other chromaffin cells of sympathetic ganglia. Typically subdiaphragmatic but can be anywhere along sympathetic chain from neck to bladder.
- Organ of Zuckerkandl (along Ao bifurcation to level of bladder) and urinary bladder are relatively common sites.

ADRENAL METS

4th MC site of hematogenous mets after lungs, liver and bone.

Melanoma (50%), lung/breast (30-40%), renal/GIT (10-20%)
Rich adrenal blood supply for endocrine function. As a result, adrenal glands are common site for hematologic mets (lung, breast, melanoma)
Unilateral or bilateral; central necrosis +/- hemorrhage
Usually <5 cm, larger if melanoma.
Must differentiate b/n isolated benign adrenal lesion (typically adenoma) and mets during initial staging:

Most mets show prolonged washout pattern unlike adenoma. Rapid washout if hypervascular mets.

ADRENAL HEMORRHAGE

ADRENAL HEMORRHAGE STATdx

Can be spontaneous but in adults is usually due to anticoagulation or an underlying malignancy.
Hemorrhage can appear mass-like and is often heterogeneous on CT but does not enhancement of postcontrast images.
When prior imaging is available, it should be suspected in the event of rapid onset of an adrenal mass.
In this context F/U imaging can be helpful to confrim resolution and/or interval decrease in size.

ADRENAL HYPERPLASIA

ADRENAL HYPERPLASIA STATdx

Enlargment of adrenal glands

Adrenal body > 10 mm, limbs >5 mm
Typically bilateral and smooth w/ maintained shape
Majority are nonfunctional. minority demonstrate subclinical or clinical adrenal dysfunction.

ADRENAL CALCIFICATION

Adrenal calcifications are not infrequent bu rarely cause adrenal hypofunction.

Can be 2/2 hemorrhage, granulomatosis w polyangiitis, TB, and histoplasmosis.

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