Hepatic small vessel neoplasm: not totally benign, not yet malignant

Abstract

Hepatic small vessel neoplasm (HSVN) is a rare vascular tumor with few reports in the literature. While imaging findings may show characteristic enhancement patterns, limited available literature may not reveal the full potential for image-based diagnosis. Histologically, HSVN mimics other entities, though certain morphologic and immunohistochemical findings provide clues for diagnosis. However, HSVN still provides diagnostic challenges, especially on core biopsies with limited material for morphologic and molecular evaluation. While current recommendations are surgical resection and close observation, the long-term course of the tumor is unknown. We report a case of HSVN in a liver with additional feature of organized lymphoid aggregates necessitating additional hematopathology consultation and workup to rule out concurrent entities.

Keywords: Hepatic small vessel neoplasm; Liver; Vascular neoplasm.

Fig. 1.

(A) Liver ultrasound demonstrating a hypoechoic lesion in the right lobe of the liver. (B) Liver protocol abdominal magnetic resonance imaging showing a hyperintense lesion on T2 with heterogenous contrast enhancement.

Fig. 2.

Microscopic appearance of the biopsy specimen. (A) Multiple biopsy specimens with well-demarcated lesion. Multiple, various-sized lymphoid aggregates can be seen. (B) The lesion is composed of thin-walled small vascular channels lined by bland endothelial cells. (C) The lesion is well-demarcated from adjacent liver parenchyma in most areas. (D) Focal infiltration into portal tract.

Fig. 3.

Immunohistochemical staining. (A) Lesion next to normal hepatic parenchyma. (B) The lesion is positive for CD31. (C) Positive for CD34. (D) Positive for ERG. (E) p53 is patchy and weak. (F) Ki-67 proliferation index is 5%–10%.

Fig. 4.

Immunohistochemical staining of lymphoid aggregate. (A) Varying sized aggregates of small lymphoid cells were present in the lesion. (B) CD3 stains a moderate number of small T cells. (C) CD20 stains a small number of small B cells. (D) CD8 did not demonstrate organized lymphoid tissue.