Nonomura A, Enomoto Y, Takeda M, Tamura T, Kasai T, Yosikawa T, Nakamime H
Department of Diagnostic Pathology, Nara Medical University, School of Medicine, Kashihara, Nara, Japan.
Histopathology. 2006 Jun;48(7):831-5. doi: 10.1111/j.1365-2559.2006.02427.x.
Although histological features of hepatic angiomyolipoma (AML) are highly variable, true malignant change is extremely rare. The aim was to review the histological features of invasive growth and clinical outcomes in 39 cases of hepatic AML.
An invasive growth pattern into surrounding hepatic parenchyma, portal triads and/or around hepatic veins was found in 24 of 39 tumours (62%). One variant showed tumour cells replacing hepatocytes within the liver cell cords. The other consisted of portal or perivascular invasive growth along blood vessels. In the former pattern, small isolated tumour cell clusters were occasionally found in the vicinity of the main mass, showing a sprouting pattern. Although these histological features suggest malignancy, distant metastases were not found in any of the cases within a mean follow-up period of 6.8 years.
A previously unrecognized histological feature of an invasive growth pattern, which suggests malignancy and might promote an erroneous diagnosis, was frequently found in hepatic AMLs. However, among about 180 reported hepatic AMLs, including the present cases, only one hepatic AML with distant metastasis has been reported to date and nearly all hepatic AMLs behave in a benign fashion. Therefore, pathologists should not overdiagnose malignancy based solely on the histological invasive growth patterns described in this paper.
尽管肝血管平滑肌脂肪瘤（AML）的组织学特征高度可变，但真正的恶性转变极为罕见。本研究旨在回顾39例肝AML的侵袭性生长组织学特征及临床结局。
39例肿瘤中有24例（62%）呈现向周围肝实质、门三联管和/或肝静脉周围的侵袭性生长模式。一种变异型表现为肿瘤细胞取代肝索内的肝细胞。另一种则是沿血管的门脉或血管周围侵袭性生长。在前一种模式中，在主肿块附近偶尔发现小的孤立肿瘤细胞簇，呈芽生模式。尽管这些组织学特征提示恶性，但在平均6.8年的随访期内，所有病例均未发现远处转移。
肝AML中经常发现一种先前未被认识的侵袭性生长组织学特征，该特征提示恶性且可能导致误诊。然而，在包括本病例在内的约180例已报道的肝AML中，迄今为止仅报道了1例发生远处转移的肝AML，几乎所有肝AML均表现为良性。因此，病理学家不应仅根据本文所述的组织学侵袭性生长模式过度诊断恶性肿瘤。
