Abstract
BackgroundSpontaneous regression of hepatocellular carcinoma (HCC) is a rare event, and its clinicopathological features and underlying mechanism are not fully understood.Case presentationAn 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.ConclusionsWe 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.
Highlights
ConclusionsWe consider this case representative of spontaneous regression of hepatocellular carcinoma (HCC), and the immune response against HCC might contribute to tumor regression, leading to complex histopathological appearances
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
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
Summary
A case of possible spontaneous regression of HCC in a Japanese female patient was reported. The immune response against HCC might contribute to tumor regression, leading to complex histopathological appearances such as dense infiltration of TILs, coagulative necrosis of HCC, uneven expression of PD-L1 within the tumor, and the formation of inflammatory pseudotumor-like lesions. Cases of HCC showing such features have not been described in the literature, and this case may provide initial insights into the mechanism of the spontaneous regression of HCC
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