Hepatic nodular regeneration of the liver and spleen
is a benign, usually insignificant finding that is relatively common in
both dogs and cats. There
are multiple causes of nodular regeneration including current or
previous administration of steroids, non-steroidal anti-inflammatories
and other drugs. In many cases, the etiology is unknown. The prognosis is very good.
Sonographically animals with nodular regeneration will
have a few to multiple, well defined, round hypoechoic or hyperechoic
nodules seen scattered throughout the liver and / or spleen.
The nodules will typically be less than 1 cm in diameter, however
in rare cases, larger nodules can occur.
The nodules are surrounded by normal liver/spleen parenchyma.
The nodules will rarely cause bulging of the capsular margins.
Although nodular regeneration is usually an
insignificant finding, it appears sonographically identical to
metastatic nodular disease of the liver or spleen which is a VERY
significant finding. Unfortunately,
there is no way to non-invasively differentiate benign nodular
regeneration from metastatic nodular disease.
Ultrasound guided fine needle aspirates or true-cut biopsy is
required for a specific diagnosis.
