Antenatal detection and management of suprarenal masses
Article Outline
Abstract
The indications for, and timing of, surgical intervention for suprarenal masses detected prenatally are unclear. Also, the definitive diagnosis of suprarenal masses using imaging studies is difficult at best. We report 2 cases of antenatally detected suprarenal masses. One case represents an initial cystic mass expanding and becoming solid that had benign pathologic features. The second case was a stable solid mass that, on exploration, was malignant. Management options are discussed.
T he detection of a suprarenal mass in the fetus and infant is usually a cause for concern, particularly when the mass is solid and fails to regress. Our recent experience with 2 cases forms the basis of this report.
Case reports
Case 1
A 37-year-old woman (gravida 6, para 4, abortio 1) presented at 35 weeks of gestation for her first routine antenatal care visit. Her past obstetric history was significant for four vaginal deliveries and one cesarean section because of placenta previa and premature rupture of membranes. A pelvic ultrasound was performed because of the history of placenta previa. A cystic mass measuring 2.2 × 1.7 cm was seen adjacent to the upper pole of the fetal left kidney (Fig. 1A). A follow-up ultrasound 2 weeks later revealed the mass to be larger and more solid appearing (Fig. 1B). Finally, an ultrasound examination at 39 weeks’ gestation revealed oligohydramnios, and therefore we were unable to evaluate the kidneys. Subsequently, the mother underwent an induced vaginal delivery of a healthy 3400-g boy. On physical examination, the left kidney was palpable. The remainder of the examination was normal. A postnatal ultrasound examination showed a predominantly solid suprarenal mass deforming the upper pole of the left kidney (Fig. 1C). Serum electrolytes, complete blood count, ferritin, and transaminases were normal. Urinalysis was normal. Twenty-four hour urinary homovanillic acid and vanillylmandelic acid were normal, as was a chest x-ray and bone survey. Magnetic resonance imaging confirmed a 2-cm mass appearing to arise from the upper pole of the left kidney (Fig. 1D). The adrenal gland could not be identified. Indium-111-diethylenetriaminepentaacetic acid (111In-DPTA)-octreotide scintigraphy was done to identify neuroendocrine tumor tissue (Fig. 2). The findings were negative.
FIGURE 1.
(A) Antenatal ultrasound showing cystic left upper pole mass (35 weeks). (B) Same patient at 37 weeks’ gestation. Mass is larger and more solid appearing. (C) Postnatal image showing a predominantly solid mass deforming the upper pole. (D) Magnetic resonance image confirming 2-cm mass arising from the left upper pole.
FIGURE 2.
111In-DTPA-octreotide scintigraphy used to determine neuroendocrine origin of mass (negative).
Exploration was undertaken because of the expanding nature of the mass. Radical nephrectomy was performed, as the mass was densely adherent to the diaphragm and surrounding structures. Pathologic examination revealed a hemorrhagic pseudocyst of the adrenal gland and a normal kidney.
Case 2
A 32-year-old primigravid woman near term presented to her obstetrician at a peripheral hospital. An obstetric ultrasound was performed, which revealed a solid fetal suprarenal mass on the left. The mother underwent a scheduled cesarean section, delivering a healthy boy who was then referred to our hospital. The boy was normotensive. Physical examination revealed subcoronal hypospadias. The remainder of the examination was normal. A postnatal ultrasound showed the mass to be the same size. Computed tomography and magnetic resonance imaging confirmed a solid mass with central calcifications. Serum chemistries were normal. Urinary vanillylmandelic acid was slightly elevated. The mass was observed for 2 weeks, and a follow-up sonogram revealed no diminution in size. At exploration, the left adrenal was splayed atop a spherical, dark purple, soft mass. There was no distinct plane between the mass and the adrenal gland; therefore, radical nephrectomy was performed. Frozen section revealed neuroblastoma. A periaortic and renal vein lymphadenectomy, liver biopsy, and bone marrow aspiration were also performed. Final pathologic examination revealed Stage I neuroblastoma, with favorable histologic features. Permanent sections did not reveal kidney involvement. The DNA was diploid, and the N-myc oncogene was not amplified.
Comment
Definitive diagnosis of suprarenal masses using imaging studies is difficult at best. The differential diagnosis includes benign entities such as adrenal hemorrhage, renal cystic disorders, duplication with upper pole moiety dilation, focal renal dysplasia, pulmonary sequestrations, and enteric duplication cysts. Malignant diseases, including neuroblastoma and congenital mesoblastic nephroma, must also be considered.1
Adrenal hemorrhage, the most common adrenal mass in the neonate, is rarely detected prenatally, but its sonographic appearance varies with the evolution of the process. Initially, it may appear hyperechoic or solid. Over time, the lesion becomes increasingly hypoechoic, and, typically, diminishes in size with cystic degeneration and reabsorption of clot.2 The appearance on magnetic resonance imaging usually varies with the progression of hemoglobin breakdown. Early hemorrhage appears hypointense on T1-weighted and hyperintense on T2-weighted images. These evolve to hyperintense lesions surrounded by a thin dark rim on both images.3
Neuroblastoma, the most common adrenal malignancy in infancy, can have a mixed echotexture sonographically. The prenatal appearance is variable and has been described as solid, cystic, and mixed. The echotexture is usually stable, and the mass may increase in size over time. Magnetic resonance imaging may clearly define the organ of origin and the extent of metastatic spread, appearing isointense or hyperintense on T1-weighted and hyperintense on T2-weighted images.4 Combined subtraction scans with dimercaptosuccinic acid and 111In-DTPA-octreotide may be helpful in identifying adrenal tumors because of the affinity of the isotope for neuroendocrine tumor tissue.5 Although the scan was negative in our first case, it did not preclude exploration, as the mass was expanding. Congenital mesoblastic nephroma is the most common renal tumor of infancy, with a mean age at presentation of 3.5 months. Histologically, it appears as a tumor of fibroblasts and smooth muscle cells (hamartoma) that infiltrate the renal parenchyma, potentially invading adjacent structures.6 It is rarely metastatic in nature, but carries a 20% local recurrence rate after surgical resection. Sonographically, it appears as a solid mass without a clearly defined capsule. It is often associated with polyhydramnios. This tumor requires tissue diagnosis, as it is difficult to differentiate it from other renal tumors.7
Conclusions
When confronted with an antenatal mass in the renal fossa suspected to be of adrenal origin, a period of “aggressive observation” is warranted. Sonographic studies should be repeated at frequent intervals. Clinical management will depend to a large extent on the evolution of the mass with regard to its size and echogenicity. It is safe to adopt such an approach in the neonate only because of the relatively low level of malignant activity in the tumors found in this age group. This approach would likely increase the chances of renal preservation.
References
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PII: S0090-4295(99)00425-2
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