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SIZE In length, the adrenal gland is 3-5 cm long; its transverse dimension is 1-2 cm and its antero-posterior is 4-6 mm. The gland weighs in at 8 gm and has a volume measuring ___. Each glands is 3-5 cm long, 1-2 cm wide, and 4-6 mm thick. Together, the two weight about 8 gm, though their weight and size vary with age and physiologic condition.

The adrenals can vary in weight anywhere between 4 to 14 grams, but the average weight is between 3 to 6 grams. Only about 10% of the gland’s weight is from the medulla (inner portion).The average adrenal dimensions are:

·         20-30 mm. in width

·         40-60 mm. in length

·         3-6 mm. in thickness

The left adrenal is slightly larger than the right.

As previously stated, the limbs of the adrenal glands should be as gracile and as thin as the crura. In many instances however the gland gets distorted by surrounding structures and becomes thicker than the crus as seen by distortion of the left adrenal gland in this case.Courtesy of: Ashley Davidoff, M.D.  .Courtesy of: Ashley Davidoff, M.D.
In this case the normal medial limb of the right adrenal gland is elongated. This is a normal variant. The lateral limb is pushed against the liver.Courtesy of: Ashley Davidoff, M.D.
In this instance the adrenal size is clearly abnormal. The abnormal areas of metastatic disease are overlayed in green. The thickening of the medial limb of the right and the mass on the left result in an increased size of the each of adrenal glands.Courtesy of: Ashley Davidoff, M.D.

Anatomy and Physiology of the Adrenal Glands: Size – small and large

The tiny subcentimeter green nodule at the apex of the left adrenal is a surgically proven aldosteronoma, which is a benign tumor that produces excessive aldosterone and causes hypertension. If left untreated devastating effects of hypertension result.
This massive adrenal carcinoma (in green overlay) occupies almost the entire left side of the abdomen, and is so bulky that it has literally pushed the left kidney (red overlay)down to the pelvis, and rightward to the right kidney. Sometimes adrenal carcinomas produce hormones with functional effects relating to the type of hormone they produce.Images courtesy of: Ashley Davidoff, M.D.

Other Nodules and Masses

Abnormal Gland

Adrenal gland abnormality can vary from subtle thickening of the limbs as seen in hyperplasia, to small subcentimeter adenomatous nodules, to multiple tiny nodules of hyperplasia, to 6cm. (or more) masses. Attention to detail and imaging technique is key to the diagnosis of the abnormal gland.

Masses can be classified according to their size.

Conditions producing small masses less than 4 cm. include:

adenoma
hyperplasia
metastasis
pheochromocytomas

Conditions with larger masses greater than 4 cm. include:

cysts
hematomas
metastasis (especially from breast and lung cancers)
myelolipomas
pheochromocytomas belonging to the MEN syndrome

When a mass is greater than 6cm., the most likely diagnosis is a primary carcinoma.

Anatomy and Physiology of the Adrenal Glands: Incidentaloma

An “incidentaloma” is the most common adrenal tumor. It represents a small benign adenoma, (“oma” = tumor) of no functional significance, which is found incidentally, and hence its name. A nodule that is less than 3cm. with a density of less than 10 HU on CT, is diagnostic of the “incidentaloma”. The characteristic finding on MRI is a darkening in the “out of phase” T1 sequence of the tumor .

In this CT scan, the green overlay is a soft tissue nodule that was found incidentally.Courtesy of: Ashley Davidoff, M.D.

 

The nodule is oval, with smooth borders, measures less than 3cm., (left image) and has a density of 2.6 HU. (right image) It is a classical “incidentaloma” or benign adenoma. No further workup is needed.Courtesy of: Ashley Davidoff, M.D.

Anatomy and Physiology of the Adrenal Glands: Bilateral Adrenal Masses

In a patient with a known malignancy, particularly in lung or breast carcinomas, the finding of bilateral adrenal masses most likely represents metastatic disease. However, documenting the entity of metastatic adrenal disease is sometimes a decision focus for the type of treatment a patient may receive. In these circumstances, an adrenal biopsy must be performed .


The finding of bilateral masses (green overlay), in a patient with a known malignancy most likely represents metastatic disease. This patient has known lung carcinoma and bilateral masses with peripheral enhancement, which almost certainly represents metastatic disease.Courtesy of: Ashley Davidoff, M.D.

The most common causes of bilateral adrenal enlargement include:

metastases (especially lung and breast)

bilateral adenomas,

hemorrhage; spontaneous,: (particularly in infants),

traumatic, and bleeding disorders.

Less common causes include:

·         histoplasmosis and tuberculosis

·         neuroblastoma

·         pheochromocytoma

Additionally, rare causes include:

·         Addison’s disease

·         amyloidosis

·         lymphoma


This is a rare case of bilateral adrenal enlargement in a patient with end stage lymphoma.Courtesy of: Ashley Davidoff, M.D.

Cyst in the Adrenal

Cysts in the adrenal are not uncommon and they may be quite large. Adrenal cysts are fluid containing structures enclosed by a thin smooth wall. In general, adrenal cysts have no functional or clinical significance. MRI is the best method of confirming their make up and morphology.

This MRI scan through the upper abdomen shows a fairly large mass in the left adrenal that is dark on T1-weighting, and is as bright as CSF on the T2-weighted image. These findings are characteristic of a benign cyst. No further workup is needed. Note how the right adrenal is compressed against the liver with only the medial limb in view.Courtesy of: Ashley Davidoff,
Size and Shape
Cross section of the arenals showing gracile limbs in the shape of a chicken bone.
Each limb is about the width of the crus of the diaphragm.
The inner medulla is colored in red and the outer cortex in yellow.
Ashley Davidoff MD 2018
adrenals-0002

 

Wishbone Shape of the Adrenal Gland
In general the adrenal glands are triangular in shape and are reminiscent of the shape of the ?wishbone? or the breast bone of the chicken.
Courtesy of: Ashley Davidoff, M.D.
Wishbone Shape on the CT scan
The right adrenal gland, in this case, looks exactly like the inserted drawing of the ?wishbone?. This represents the typical appearance of the glands ? the right long and thin, and the left short and stout. The bright red overlays represent some of the branches of the adrenal arteries.Courtesy of: Ashley Davidoff, M.D.
Adrenal and Cerebral Dystrophy ? Inherited
31464c04 26 male adrenal brain white matter dx adrenal leukodystrophy inherited
Davidoff MD Courtesy Rebecca Schwartz
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