Possible Spontaneous Regression Of Hepatocellular Carcinoma With Unique Histopathological Features Confirmed By Surgical Resection: A Case Report

Kimura, T. 2021Liver cancer

Kimura, T., Goi, T., Yokoi, S., Ohnishi, K., Togawa, T., Iida, A., Ishida, M., & Sato, Y. (2021). Possible spontaneous regression of hepatocellular carcinoma with unique histopathological features confirmed by surgical resection: a case report. Surgical case reports, 7(1), 162. https://doi.org/10.1186/s40792-021-01246-z

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Abstract

BACKGROUND: Spontaneous regression of hepatocellular carcinoma (HCC) is a rare event, and its clinicopathological features and underlying mechanism are not fully understood. CASE PRESENTATION: An 84-year-old female with hepatitis C virus infection and diabetes mellitus was referred to our hospital for further examination. Abdominal ultrasonography showed a 3.4-cm solid tumor with a heterogeneous irregular center and no fibrous capsule in liver segment 8 (S8). An enhanced computed tomography (CT) scan revealed a tumor in S8 with heterogeneous enhancement in the arterial phase and washed out insufficiently in the portal and equilibrium phase. The enhanced pattern on magnetic resonance imaging was similar to that of CT. Although the imaging findings were not typical for HCC, liver resection (S8) was performed with HCC as the most probable diagnosis. Histopathological examination of the resected specimen showed that the tumor was well to moderately differentiated HCC with unique features. Approximately half of the tumor was composed of well-differentiated HCC that was focally accompanied by dense lymphocyte infiltration. The other half of the tumor was fibrotic tissue that resembled an inflammatory pseudotumor. Several foci of moderately differentiated HCC were scattered within the tumor with a nodule-in-nodule appearance, and the foci totally showed coagulative necrosis. On immunostaining, lymphocytes in the tumor stroma were positive for CD8 and programmed death 1. The expression of programmed death-ligand 1 was observed in carcinoma cells and macrophages specifically within the lymphocyte-rich area of HCC. CONCLUSIONS: We consider this case representative of spontaneous regression of HCC, and the immune response against HCC might contribute to tumor regression, leading to complex histopathological appearances. This case may provide insight into the mechanism of spontaneous regression of HCC.

Case Details

Disease Location

Liver

Personal Characteristics

84-year-old japanese female with hepatitis c virus (HCV)-associated chronic hepatitis and diabetes mellitus treated with insulin

Clinical Characteristics

Referred for further examination because of elevated α-fetoprotein (AFP) in a routine blood test. With slightly elevated aspartate aminotransferase. Abdominal ultrasonography showed a 3.4-cm solid tumor in liver segment 8 (s8), with a heterogeneous irregular center but no fibrous capsule. CT showed heterogeneous enhancement in the arterial phase and washed out insufficiently in the portal and equilibrium phase. MRI revealed a tumor in s8 with low-to-iso-intensity on t1-weighted imaging, high-to-iso-intensity on t2-weighted imaging, high intensity on diffusion-weighted imaging, and low intensity on hepatocellular imaging. Liver resection (s8) was performed. The cut surface of the tumor grossly showed a heterogeneous appearance. Histological examination showed that it had several different components. Hepatocyte-like cells were arranged in a thin trabecular pattern with increased cellularity. Within the nodule of well-differentiated hcc, an area accompanied by marked lymphocyte infiltration in the tumor stroma was noted. One half of the tumor was replaced by fibrotic tissue, accompanied by infiltration of lymphocytes and foamy macrophages.

Remission Characteristics

Small nodules were entirely composed of necrotic tissue, and a thick trabecular pattern could be recognized by reticulin staining, indicating moderately differentiated hcc with extensive coagulative necrosis, existing in a nodule-in-nodule pattern.