Background/aims: Cavernous hemangiomas (CH) are typically described as solitary, well-circumscribed lesions and are reported to have a distinct fibrous interface. This study describes underrecognized histological changes of large hepatic hemangiomas that contradict this long-standing view.
Methods: Nineteen cases of hepatic resections for CH were reviewed. Stains for estrogen and progesterone receptors (ER/PR), MIB-1, alpha-smooth muscle actin, collagen IV, and elastic Van Gieson stains were applied to the lesions.
Results: The CHs measured 5-31 cm (mean 16.6 cm). Sixteen (84%) CHs had an irregular interface with the liver parenchyma while only three had the well-defined fibrous capsule typically described for CH. Fifteen (79%) CHs had dilated vascular spaces filled with blood 0.1-2.0 cm beyond the confines of the main CH, which we have designated hemangioma-like vessels (HLVs). The histochemical and immunohistochemical stains in both CH and HLVs were similar, with the walls of the vessels composed predominantly of collagen with some faint elastic fibers and smooth muscle, endothelium underlined by collagen IV, negative ER/PR in all components, and a proliferation rate of <5/100 endothelial cells.
Conclusion: Irregular edges of CH and HLVs in the liver parenchyma adjacent to CH have been underrecognized. No significant differences in staining or proliferative rate were present between CHs and HLVs, suggesting the HLVs are within the spectrum of CH.