J Korean Radiol Soc 1999 ; 40: 173-179 Imaging Findings ofNeonatal Adrenal Disorders 1 Hye-Kyung Yoon, M.D., Bokyung Kim Han, M.D., Min Hee Lee, M.D. In newborn infants, normal adrenal glands are characterized by a relatively thin echogenic center surrounded by a thick, hypoechoic cortical rim as seen on ultrasound (US). Various disorders involving the neonatal adrenal gland include ad renal hemorrhage, hyperplasia, cyst, Wolman’s disease, and congenital neuro­ blastoma. Adrenal hemorrhage is the most common cause of an adrenal mass in the neonate, though differentiation between adrenal hemorrhage and neuroblastoma is in many cases difficult. We describe characteristic US, CT and MR imaging findings in neonates with various adrenal disorders. Index words : Infants, newborn, genitourinary system Adrenal gland, abnormalities Neonatal adrenal glands are clearJy demonstrated on uJtrasound (US) using high-freguency linear or phased Normal Neonatal Adrenal Glands array transducers. The normaJ neonataJ adrenaJ gland is clearly seen on postnatal abdominal sonograms, The appearance of neonatal adrenal glands varies; consisting of an echolucent cortex and a thinner they may be lambdoid, V- or Y-shaped, and are rela echogenic centraJ med ull a. AdrenaJ hemorrhage is the tively large (1). On US, corticomeduJJ ary differen most common adrenal mass in neonates. US is used as tiation is evident, with an outer echolucent cortex and the initiaJ modaJity for diagnosing adrenaJ hemor­ a central echogenic line representing the medulla (Fig. rhage, the appearance of which is varied and changes lA and B). The cortex is prominent in normal newborn over time. Other less frequent disorders occurring in infants because of the presence of a thick transient the neonatal adrenal glands include congenital adrenal fetal cortex, which involutes rapidly during the first hyperplasia (adrenogenitaJ syndrome), lipoid adrenaJ three weeks of life and completes the synthesis of ma­ hyperplasia, adrenaJ cyst, W oJm an’ s disease, and con­ ternally produced precursor steroids to make genital neuroblastoma. Computed tomography (CT) is estrogens d uring the third trimester of pregnancy. excellent for depicting calcification or fat density After the neonatal period, the hypoechoic peripheral associated with adrenallesions but beca use of the lack zone becomes smaller on US as the fetal cortex of retroperitoneal fat is less usefuJ for the demon­ involutes. When ipsilateral renal agenesis or ectopia is stration of normaJ adrenal glands. CT and/or magnetic present, the shape of adrenal gland is discoid and resonance (MR) imaging may be helpful for evaJuating elongated (Fig. lC). the extent and tissue characterization of an adrenal mass. Adrenal Hemorrhage Idiopathic neonataJ adrenal hemorrhage is usuaJJy asymptomatic and freguentJy discovered as an inci­ IDcparlmcnt of Radiology, Samsung Medi ca l Cc ntcr, Sungk y unk wa n Uni versity dentaJ finding on US (1). A large baby, difficult deliv­ Co ll egc 0 1' Medici nc ery, and perinatal hypoxia have been reported as pre­ Rcceived June 5, 1998 ; Accepled Se plember 8, 1998 Addrcss reprinl requcsls to: Hye-Kyu ng Yoon, M.D. , Depar tment ofRad io logy, disposing factors in neonataJ adrenaJ hemorrhage. On Sa msu ng Medica l Center, ~ 50 Irwon-d o ng, Kangnam-gll , SCO ll l. 135-7 10, US, hemorrhage can be echogenic, echolucent or Korca TeI. 82-2-3410-25 18 Fax.82- 2-3410. 2559 - 173 - Hye-Kyung Yoon, et al : Imaging Findings of Neonatal Adrenal Disorders mixed in appearance, depending on its age (Fig. 2, 3) pletely obliterated. A diagnosis of adrenal hemorrhage The adrenal gland may be discernible in part or com is based on sequential US examinations and involves A B Fig. 1. Normal adrenal glands in new born infants A. Abdominal US in a newborn infant shows lambda­ shaped right adrenal gland (arrows) with thick echolucent cortex and echogenic central line of the medulla. RK = right kidney. B. US with prone position in another newborn infant demonstrates large and thick limbs of the adrenal gland (arrows). The corticomedullary differentiation is clearly seen. C. Longitudinal US through the right renal fossa shows the elongated adrenal gland (arrow). In this case, right kidney (not shown) was seen in lower abdominal cav 때 and was fused with the lower pole of left kidney (crossed fused ectopyl C A B Fig. 2. Neonatal adrenal hemorrhage A. Longitudinal US shows left adrenal hemorrhage (calipers) with mixed solid and cystic appearance. Note relative preser­ vation ofthe normal triangular shape. LK = left kidney. B. Three months later, left adrenal hemorrhage seen on the figure A is completely resolved. - 174 - J Korean Radiol Soc 1999; 40: 173-179 demonstration of liquefaction and regression. Calcifi Adrenal hemorrhage may involve only a part of the cation at its periphery is common (Fig. 3C). Due to the adrenal gland even when normal contour is preserved paramagnetic effect of methemoglobin, MR imaging (2). When it primarily involves the adrenal medulla, (Fig. 3B) clearly shows adrenal hemorrhage of high sig­ normal configuration of the gland and the cortex is nal intensity on precontrast Tl-weighted images. preserved (Fig. 4) A B Fig. 3. Neonatal adrenal hemorrhage with calcification. A. Longitudinal sonogram shows adrenal hemorrhage (H) above right kidney (RK), with a predominantly solid appear­ ance B. Tl -weighted axial MR image shows a large hyperintense hematoma (arrowheads) in the right adrenal gland with central isosignal intensity suggesting resolving hemorrhage. c. Two weeks later, right adrenal hemorrhage has decreased in size with eggshell-like calcification in the periphery of the resolving hematoma (arrowheads). RK = right kidney C A B Fig. 4. Adrenal med 1I11 ary hemorrhage in a newborn Transverse (A) and longitudinal (B) US scans of the adrenal region show normal hypoechoic co rtices of both adrenal glands (arrowheads)‘ However, echogenic adrenal med lI11ae (m) are markedly thickened. 175 Hye-Kyung Yoon , et al : Imaging Findings of Neonatal Adrenal Disorders tumor (Fig. 5C and D) Congenital Adrenal Hyperplasia Congenital Li poid Adrenal Hyperplasia Enzymatic defects at any site of adrenal steroid biosynthesis result in cortisol deficiency and second­ Conversion of cholesterol to pregnenolone is an es ary overproduction of pituitary corticotropin, which sential step in the synthesis of all adrenocortical in turn overproduces androgens. Congenital adrenal hormones. Infants with 20, 22-desmolase deficiency hyperplasia or adrenogenital syndrome causes am­ cannot synthesize any glucocorticoid, mineralo­ biguous genitalia, pseudohermaphroditism in females corticoid, or sex steroid. The adrenal glands are and an enlarged penis and precocious puberty in enlarged and filled with cholesterol and other lipids, males. Deficiency of 21-hydroxylase is the most com­ which explains echogenecity on US and hypodensity mon form of congenital adrenal hyperplasia, and dif­ on CT scan (5) (Fig. 6) fuse or nodular enlargement of the adrenal cortex occurs in many but not all babies with this condition Adrenal Cyst (2 , 3). US may show diffuse adrenal enlargement with a wrinkled, wavy, cerebriform appearance and loss of Adrenal cysts may be parasitic, epitheliaL endo normal corticomedullary differentiation (Fig. 5). Oc thelial or pseudocysts; true epithelium-lined adrenal casionally, adrenal enlargement may mimic adrenal cysts are rare in the neonate. Cystic lesions of the mass but bilateral involvement with relative preser­ adrenal glands are usually pseudocysts (hemorrhagic vation of gland configuration can exclude adrenal cysts) secondary to resolving adrenal hemorrhage. A B Fig. 5. Congenital adrenal hyperplasia in a newborn girl with virilization and dark pigmentation Right (A) and left (8) adrenal glands show diffuse enlargement with cer­ ebriform appearance (arrows). L = liver, S = spleen. C. Transverse US in another female infant with congenital adrenal hyper­ plasia reveals diffuse enlargement of bilateral adrenal glands (arrowheads). D. T2-weighted coronal MR image in the same patient to C shows diffuse enlargement of the adrenal glands (arrows) with preservation ofthe nor­ mal triangular configuration C D τω J Korean Radiol Soc 1999 ; 40: 173-179 Adrenal cystic masses h ave been d escribed in associ­ ation with complete or incomplete forms of Beckwith­ Wolman’ s Disease Wiedemann syndrome (6, 7) (Fig. 7) . Because an adrenal cyst cannot be clearly distinguished from the Wolman’ s disease is a fatal xanthomatosis of cystic neuroblastoma occurring in association with autosomal recessive inheritance and is characterized Beckwith-Wiedemann syndrome, close observation, as by failure to thrive, hepatosplenomegaly, vomiting, well as US or surgical con firmation , is needed. and steatorrhea. Uniform bilateral adrenal enlargement with calcification is pathognomonic (8). Calcification Fig. 6. Congenitallipoid adrenal hyperplasia. A. Longitudinal US scan of the left f1 ank shows enlarged adrenal gland (arrows) above the left kidney (LK). The gland appears diffusely echogenic with loss of corticomed ullary differentiation. A 8. Unenhanced CT scan at the level of adrenal gland shows thickened both adrenal glands with low attenuation, indicating fatty infiltration A B c Fig. 7. Adrenal cystic mass in a newborn girl with Beckwith-Wiedemann syndrome Longitudinal US sca n (A) shows a large, well-demarcated cystic mass with homogeneous internal echoes above the right kid ney (RK). T2-weighted (8) and postcontrast Tl -weighted (C) coronal images