Osamu Sakai, Shin-ichi Nakamura, Hinami Kodama, Sho Kadekaru, Akihiko Sugiyama, Ryohei Yoshitake, Kenji Kutara
Background
Primary hepatic leiomyosarcoma (PHL) is a rare tumor in both human and veterinary medicine. While PHL is poorly understood in dogs and rarely reported, it can present with nonspecific clinical signs and mimic other hepatic conditions. This case report describes the clinical, imaging, and pathological features of a canine PHL, contributing novel insights into its diagnostic profile.
Methods
A 13-year-old male Shetland sheepdog presented with jaundice, lethargy, and anorexia. Diagnostic workup included ultrasonography, triple-phase computed tomography (CT), and postmortem magnetic resonance imaging (MRI). Histopathology and immunohistochemistry of the hepatic mass were performed after euthanasia to confirm the diagnosis.
Results
Ultrasound identified a hypoechoic liver mass without detectable blood flow. CT showed a 4.6 × 3.2 × 3.4 cm midline hepatic mass with low precontrast attenuation (28 HU) and peripheral enhancement in all phases, indicating poor central perfusion. MRI postmortem revealed low T1-weighted and high T2-weighted signal intensity. The tumor obstructed intrahepatic veins and caused left lobe atrophy and right lobe enlargement. Histopathologically, the tumor displayed interlacing bundles of spindle cells with moderate nuclear atypia and mitotic activity. Immunohistochemistry showed strong positivity for vimentin, partial positivity for α-smooth muscle actin (α-SMA) and desmin, and negativity for S100 and CD117, confirming the diagnosis of PHL.
Limitations
Contrast-enhanced MRI was not available due to postmortem timing. The single-case nature and postmortem imaging restrict extrapolation. Long-term clinical course and therapeutic response could not be evaluated due to the patient’s rapid decline and death.
Conclusions
This case presents detailed multimodal imaging and histopathologic features of canine PHL, which should be considered when a hepatic mass exhibits peripheral contrast enhancement and central hypoperfusion. Although rare, PHL can be aggressive and life-threatening due to its anatomical position. Early recognition may support better management, and further studies are needed to characterize its clinical behavior and optimize treatment strategies.
A, Transverse computed tomographic image at precontrast; (B) arterial phase; (C) portal venous phase; (D) delay phase. The mass showing low attenuation in precontrast CT scan and peripheral contrast enhancement (most of the mass was not contrast-enhanced) was observed in all phases. E, Dorsal computed tomographic image at the portal venous phase. The intrahepatic vein cephalad of the bifurcation to the hepatic right lateral lobe was not contrast-enhanced with this finding; the left lobes of the liver were atrophic, whereas the right lateral lobe was enlarged. The asterisk indicates the mass. Hash indicates the right lateral lobe. The black asterisk indicates gallbladder. The white asterisk indicates the mass. Hash indicates the right lateral liver lobe. The black asterisk indicates gallbladder. LL: left liver, PV: portal vein.
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