Long-term Histopathologic Follow-up of a Spherical Embolic Agent; Observation of the Transvascular Migration of HepaSphereTM.

Very few studies have been published on the long-term histopathologic follow-up of spherical embolic agents after their injection. To our knowledge, there are no reports in the literature regarding pathological analysis of the transvascular migration of HepaSphere particles. We here report a case of a patient with hepatocellular carcinoma (HCC) who underwent liver transplantation 12 months after drug eluting microsphere transcatheter arterial chemoembolization (DEM-TACE), and long-term histopathologic follow-up of the microspheres was performed. Furthermore, to our knowledge, this is the first report in which transvascular migration of a HepaSphere particle was confirmed histologically. A 60-year-old male with chronic hepatitis B was treated with entecavir and seroconversion was obtained. The patient had decompensated cirrhosis, and desired to undergo living donor liver transplantation (LDLT). However, 2 HCC tumors of 3 cm or less were detected in his liver. The transplantation surgeon proposed DEM-TACE as a bridge therapy. The HCCs were located in the right lobe and lateral segment of the liver. A 1.9 F preshaped microcatheter (ProgreatΣ, Terumo, Japan) was selectively inserted into the A3 and anterior segmental branch, 10 mg of epirubicin was injected into each artery, and the arteries were embolized with 7 mg and 13 mg of HepaSphere loaded with epirubicin, respectively. Two months later, contrast-enhanced CT displayed a complete response. At that time, lung metastasis was suspected, but after partial lung resection, the patient was diagnosed as having inflammatory granuloma. One year after DEM-TACE treatment, LDLT was performed. No cancerous cells were detected in the area where the tumor was present, but 22 HepaSphere particles were detected. All particles were present in the interstitium. Furthermore, the transvascular migration of a HepaSphere particle was histologically confirmed. The largest and smallest HepaSphere diameters were 241.6 ± 52.5 µm and 186.5 ± 41.4 µm, respectively, and deformity was 22.6% ± 13.0 %. All the HepaSpheres detected in the examined pathological specimen were noted to be extravascular.