A case of capillary hemangioma of the liver examined by contrast-enhanced ultrasonography with perfluorobutane (Sonazoid®)

Resection of the largest reported hepatic small vessel neoplasm

Hepatic small vessel neoplasm (HSVN) is a recently described vascular neoplasm of the adult liver. The neoplastic cells are positive for markers of vascular lineage (CD31, CD34, FLI-1). The distinctive morphology and infiltrative borders separate HSVN from benign vascular tumors such as cavernous hemangioma, while lack of atypical morphologic features, low to absent mitotic activity and low proliferation index distinguish it from malignant vascular tumors such as epithelioid hemangioendothelioma and angiosarcoma. Due to its infiltrative nature and lack of adequate follow-up information, the benign versus low-grade nature of this tumor is currently uncertain. We present a patient with resected HSVN involving all but the right posterior section of the liver, making this case the largest reported in the current literature.

Hepatic small vessel neoplasm, a rare infiltrative vascular neoplasm of uncertain malignant potential

Characteristic but rare vascular neoplasms in the adult liver composed of small vessels with an infiltrative border were collected from an international group of collaborators over a 5-year period (N=17). These tumors were termed hepatic small vessel neoplasm (HSVN), and the histologic differential diagnosis was angiosarcoma (AS). The average age of patients was 54years (range, 24-83years). HSVN was more common in men. The average size was 2.1cm (range, 0.2-5.5cm). Diagnosis was aided by immunohistochemical stains for vascular lineage (CD31, CD34, FLI-1), which were uniformly positive in HSVN. Immunohistochemical stains (p53, c-Myc, GLUT-1, and Ki-67) for possible malignant potential are suggestive of a benign/low-grade tumor. Capture-based next-generation sequencing (using an assay that targets the coding regions of more than 500 cancer genes) identified an activating hotspot GNAQ mutation in 2 of 3 (67%) tested samples, and one of these cases also had a hotspot mutation in PIK3CA. When compared with hepatic AS (n=10) and cavernous hemangioma (n=6), the Ki-67 proliferative index is the most helpful tool in excluding AS, which demonstrated a tumor cell proliferative index greater than 10% in all cases. Strong p53 and diffuse c-Myc staining was also significantly associated with AS but not with HSVN or cavernous hemangioma. There have been no cases with rupture/hemorrhage, disseminated intravascular coagulation, or Kasabach-Merritt syndrome. Thus far, there has been no metastasis or recurrence of HSVN, but complete resection and close clinical follow-up are recommended because the outcome remains unknown.