Fetal suprarenal masses--assessing the complementary role of magnetic resonance and ultrasound for diagnosis.

OBJECTIVE: To assess the value and complementary roles of fetal MRI and US for characterization and diagnosis of suprarenal masses. MATERIALS AND METHODS: We conducted a multi-institutional retrospective database search for prenatally diagnosed suprarenal masses between 1999 and 2012 and evaluated the roles of prenatal US and fetal MRI for characterization and diagnosis, using postnatal diagnosis or surgical pathology as the reference standard. Prenatal US and fetal MRI were assessed for unique findings of each modality. RESULTS: The database yielded 25 fetuses (gestational age 20-37 weeks) with suprarenal masses. Twenty-one fetuses had prenatal US, 22 had MRI, 17 had both. Postnatal diagnoses included nine subdiaphragmatic extralobar sequestrations, seven adrenal hemorrhages, five neuroblastomas (four metastatic), two lymphatic malformations, one duplex kidney with upper pole cystic dysplasia, and one adrenal hyperplasia. Ultrasound was concordant with MRI for diagnoses in 12/17 (70.6%) cases. Discordant diagnoses between US and MRI included three neuroblastomas and two adrenal hemorrhages. In the three neuroblastomas US was equivocal and MRI was definitive for neuroblastoma, demonstrating heterogeneous, intermediate-signal solid masses and liver metastases. In the two cases of adrenal hemorrhage US was equivocal and MRI was definitive with signal characteristics of hemorrhage. In 2/4 neuroblastomas, Doppler US demonstrated a systemic artery suggesting extralobar sequestration; however MRI signal characteristics correctly diagnosed neuroblastoma. All cases of extralobar sequestration were correctly diagnosed by US and MRI. CONCLUSION: US and MRI both accurately detect suprarenal masses. MRI complements US in equivocal diagnoses and detects additional findings such as liver metastases in neuroblastoma.

Imaging and differential diagnosis of suprarenal masses in the fetus.

Prenatal sonography and magnetic resonance imaging of suprarenal fetal masses is presented, along with clinical information and follow-up. Imaging pearls and differential considerations for each diagnosis will be discussed. Fetal suprarenal mass diagnoses include neuroblastoma, extralobar pulmonary sequestration, congenital adrenal hyperplasia, partial multicystic dysplastic kidney, renal duplication, urinoma, gastric duplication cyst, and splenic cyst. Recognizing the range of malignant and benign suprarenal fetal masses that can present on prenatal imaging can help guide patient counseling and management.

Adrenocortical development, maintenance, and disease.

The adrenal gland controls a plethora of crucial physiological functions, and dysfunction is associated with severe morbidity. Because of the vital importance of appropriate adrenal function, the development and function of the gland have been intensively studied, and these investigations have revealed fascinating developmental origins and a remarkable remodeling and regenerative capacity in the adult. This chapter, focusing on the adrenal cortex, will describe our current understanding of the development and maintenance of the adrenal gland, which has been advanced over recent years by the use of sophisticated genetic models in the study of both normal function and disease. This work has shed light on the transcriptional networks and signaling pathways involved in development and maintenance of the gland and in its pathology; these are discussed in the light of the wealth of physiological information gathered in studies of human and rodent adrenal development and function.

Disorders of adrenal development.

Human adrenal development is a complex and relatively poorly understood process. However, significant insight into some of the mechanisms regulating adrenal development and function is being obtained through the analysis of individuals and families with adrenal hypoplasia. Adrenal hypoplasia can occur: (1) secondary to defects in pituitary adrenocorticotropin (ACTH) synthesis, processing and release (secondary adrenal hypoplasia; e.g. HESX1, LHX4, SOX3, TPIT, pituitary POMC, PC1); (2) as part of several ACTH resistance syndromes (e.g. MC2R/ACTHR, MRAP, Alacrima, Achalasia, Addison disease), or as (3) a primary defect in the development of the adrenal gland itself (primary adrenal hypoplasia; e.g. DAX1/NR0B1 - dosage-sensitive sex reversal, adrenal hypoplasia congenita critical region on the X chromosome 1). Indeed, the X-linked form of primary adrenal hypoplasia due to deletions or mutations in the orphan nuclear receptor DAX1 occurs in around half of male infants presenting with a salt-losing adrenal crisis, where no obvious steroidogenic defect (e.g. 21-hydroxylase deficiency), metabolic abnormality (e.g. neonatal adrenoleukodystrophy) or physical cause (e.g. adrenal haemorrhage) is found. Establishing the underlying basis of adrenal failure can have important implications for investigating associated features, the likely long-term approach to treatment, and for counselling families about the risk of other children being affected.

Bilateral hemorrhagic adrenal cysts in an incomplete form of Beckwith-Wiedemann syndrome: MRI and prenatal US findings.

Benign hemorrhagic adrenal cysts are a cause of subdiaphragmatic mass in the fetus and neonate with Beckwith-Wiedemann syndrome. Characteristic imaging features on ultrasonography, color Doppler, and magnetic resonance imaging help differentiate adrenal hemorrhage from neonatal neuroblastoma and help avoid unnecessary surgery in these patients. Bilateral adrenal hemorrhage is self-limiting, and spontaneous resolution is the usual outcome. This report presents this rare condition with prenatal ultrasonographic and magnetic resonance imaging findings and reviews the differential diagnosis of neonatal adrenal masses.

Adrenocortical function and dysfunction in the fetus and neonate.

Under normal circumstances, the fetus is exposed to very low concentrations of cortisol until late in gestation. Perturbations of the intra-uterine environment resulting in fetal exposure to increased cortisol may have consequences not only in infancy, but also into adult life. In the postnatal period, developmental immaturity and/or the effects of critical illness on adrenal function may result in insufficient cortisol production to maintain homeostasis in the face of acute stress or illness, a situation that has been labelled 'relative adrenal insufficiency' in other acutely ill populations. The definition of inadequate adrenal function in the newborn and its possible relationship to adverse outcomes in both premature and term infants are only beginning to be characterized.

Adrenal cytomegaly: two cases detected by prenatal diagnosis.

We report our experience with two cases of adrenal cytomegaly, both of which were detected as cystic adrenal masses during prenatal ultrasonographic examinations. In Case 1, a left suprarenal cystic mass was detected in the fetus at 25 weeks of gestation. The mass, measuring 7 cm in diameter, did not show any change in size and was resected 26 days after birth. In Case 2, a right suprarenal lesion was found at 30 weeks of gestation. The cystic lesion, measuring 2 cm x 1.5 cm, did not change in size and was resected 3 months after birth. Adrenal cytomegaly is still not well known. It is characterized by the presence of large polyhedral cells with eosinophilic granular cytoplasm and enlarged nuclei in the adrenal cortex. This condition is thought to be a degenerative process but not a malignancy. Adrenal cytomegaly rarely forms cysts. It seemed to be impossible to diagnose preoperatively in our cases. Because of the difficulty of differentiating between cystic adrenal cytomegaly and other cystic diseases such as neuroblastoma, operative intervention is required in cases where the cysts do not decrease in size. Further study of a larger number of cases is needed to establish an optimal treatment protocol for these tumours.

Foetal cystic abdominal masses.

Foetal abdominal cysts are frequently found on routine antenatal ultrasound. Various sonographic features might help in their differential diagnosis. However, a definitive diagnosis is often not made until postnatal life, and detection of an intra-abdominal cyst antenatally rarely alters obstetric management. A review of possible causes of a foetal abdominal cyst is presented.

Surgical anatomy and embryology of the adrenal glands.

Gross anatomy explains the different surgical approaches to adrenalectomy and the difficulties encountered by surgeons during this procedure. Development of the adrenal glands explains the location of the ectopic sites and excess hormone production by adrenal tumors. The choice of a surgical approach is sometimes difficult and is dependent on (1) the morphology of the body; (2) the volume of the tumor, which necessitates immediate vascular control; and (3) the type of disease, which may necessitate a complete exploration of the abdominal cavity.

Adrenal hemorrhage in the newborn with evidence of bleeding while in utero.

A case is reported of bilateral hemorrhagic adrenal cysts in a newborn. Evaluation of the patient included x-rays of the abdomen, excretory urography, retrograde pyelography and sonography. The presence of a faint calcification in the region of the right adrenal at birth and further progression of calcification in the same area suggest that some initial bleeding occurred in utero.