Pseudoacini are generally a morphologic feature of hepatocellular carcinoma (HCC), being absent or rare in benign hepatocytic tumors, such as hepatocellular adenoma. However, rarely these can be seen in focal nodular hyperplasia (FNH) and may pose diagnostic challenges, especially when prominent. The study was aimed to evaluate the occurrence of pseudoacini in FNH and their clinicopathologic correlations. A total of 95 FNH cases diagnosed from 2005 to 2020 were included in the study. A pseudoacinus was defined as a circular arrangement of hepatocytes around a central dilated lumen present within the lobular parenchyma of the lesion with or without inspissated bile. Among the 95 FNH cases, 28 (29.5%) showed pseudoacini, which were prominent in 12 (12.6%) cases. Of these 3 occurred in patients above 50 years old. The pseudoacini were numerous in 3 cases, leading to an initial consideration of HCC in the differential diagnosis, and 1 case was diagnosed as well-differentiated hepatocellular neoplasm on initial biopsy. All 12 cases showed map-like staining pattern for glutamine synthetase. The hepatocytes forming the pseudoacini were positive for CK7 and HepPar1, while the inner lumina were highlighted by CD10 and bile salt export pump immunostains similar to adjacent canaliculi. The presence of prominent pseudoacini was not significantly associated with any clinical or pathologic features. The findings suggest that pseudoacini are likely manifestation of hepatocyte biliary transdifferentiation associated with chronic cholestasis in the lesion. This feature may pose a potential diagnostic pitfall especially on needle biopsies and awareness is needed to avoid misdiagnosing this as HCC.

假腺泡蛋白通常是肝细胞癌 (HCC) 的一种形态学特征，在良性肝细胞肿瘤（如肝细胞腺瘤）中不存在或很少见。然而，这些很少见于局灶性结节性增生 (FNH)，并且可能对诊断带来挑战，尤其是在突出时。本研究旨在评估 FNH 中假腺泡的发生及其临床病理相关性。该研究共纳入了 2005 年至 2020 年诊断出的 95 例 FNH 病例。假腺泡被定义为肝细胞在病变小叶实质内存在的中央扩张管腔周围呈圆形排列，有或没有浓缩胆汁。95例FNH病例中，28例（29.5%）表现为假腺泡，其中突出12例（12.6%）。其中 3 例发生在 50 岁以上的患者中。3例假腺泡较多，鉴别诊断初步考虑为HCC，1例初步活检诊断为高分化肝细胞肿瘤。所有 12 例均显示谷氨酰胺合成酶的地图样染色模式。形成假腺泡的肝细胞对 CK7 和 HepPar1 呈阳性，而内腔被 CD10 和胆汁盐输出泵免疫染色突出显示，类似于相邻的小管。突出的假腺泡的存在与任何临床或病理特征没有显着相关性。研究结果表明，假腺泡细胞可能是与慢性肝细胞胆道转分化相关的表现。1例初次活检诊断为高分化肝细胞肿瘤。所有 12 例均显示谷氨酰胺合成酶的地图样染色模式。形成假腺泡的肝细胞对 CK7 和 HepPar1 呈阳性，而内腔被 CD10 和胆汁盐输出泵免疫染色突出显示，类似于相邻的小管。突出的假腺泡的存在与任何临床或病理特征没有显着相关性。研究结果表明，假腺泡细胞可能是与慢性肝细胞胆道转分化相关的表现。1例初次活检诊断为高分化肝细胞肿瘤。所有 12 例均显示谷氨酰胺合成酶的地图样染色模式。形成假腺泡的肝细胞对 CK7 和 HepPar1 呈阳性，而内腔被 CD10 和胆汁盐输出泵免疫染色突出显示，类似于相邻的小管。突出的假腺泡的存在与任何临床或病理特征没有显着相关性。研究结果表明，假腺泡细胞可能是与慢性肝细胞胆道转分化相关的表现。而内腔由 CD10 和胆盐输出泵免疫染色突出显示，类似于相邻的小管。突出的假腺泡的存在与任何临床或病理特征没有显着相关性。研究结果表明，假腺泡细胞可能是与慢性肝细胞胆道转分化相关的表现。而内腔由 CD10 和胆盐输出泵免疫染色突出显示，类似于相邻的小管。突出的假腺泡的存在与任何临床或病理特征没有显着相关性。研究结果表明，假腺泡细胞可能是与慢性肝细胞胆道转分化相关的表现。病灶内胆汁淤积。此功能可能会造成潜在的诊断缺陷，尤其是在针刺活检时，需要注意以避免将其误诊为 HCC。