USG reveals a cystic lesion in the upper pole of the right kidney,
measuring 6 x 3 cm. The right kidney is seen clearly separate from this
lesion. This cyst displays internal echoes within suggestive of
hemorrhage. Progressive scan revealed thickening and calcification of the
wall (Fig 3), with septations within. Intra-operative findings revealed
right adrenal hemorrhage with secondary infection (pus with hemorrhagic
fluid was seen on cut section).
In adrenal hemorrhage, differentiation from neonatal neuroblastoma is
important and a follow up scan may demonstrate the mass reducing in size
and eventually resolving, confirming the diagnosis of adrenal hemorrhage.
In this case, the size remained the same and though there were changes
noted (wall calcification), in view of the hypertension, and palpable
lump, there remained a strong suspicion of cystic neuroblastoma.
US is the modality of choice for initial and follow-up evaluation of
a flank mass in a neonate. In neonates, the normal adrenal glands are
clearly visualized at US and consist of a hypoechoic cortex and
a thin, echogenic medulla. The pattern of echogenicity of an
adrenal hematoma depends again on its age. An early-stage
hematoma appears solid with diffuse or inhomogeneous
echogenicity. As liquefaction occurs, the mass demonstrates
mixed echogenicity with a central hypoechoic region and
eventually becomes completely anechoic and cystlike. Calcifications may
be seen in the walls of the hematoma as early as 1–2 weeks
after onset and gradually compact as the blood is absorbed. Color
Doppler and power Doppler imaging allow confirmation of the
avascular nature of the mass.
Alpana Joshi, Associate Professor, BYL Nair Hospital, Mumbai