Inflammatory pseudotumor is a term used to designate inflammation-rich tumefactive lesions. Following the exclusion of specific entities such as IgG4-related disease and other neoplastic entities previously included in this entity, the majority of hepatic pseudotumors show a prominent fibrohistiocytic inflammatory reaction and have been previously categorized as fibrohistiocytic variant of hepatic pseudotumor (FHVHPT). The goal of this study was to examine the clinical, radiologic, histologic, and etiologic aspects of this entity. After excluding neoplastic diseases, we identified 30 patients with FHVHPT from 3 institutions between 2009 and 2019. We extracted demographic and clinical data, liver function tests as well as culture results and radiologic information. Hematoxylin and eosin-stained slides were reviewed for pattern of inflammation as well as its cellular composition. Immunohistochemistry for IgG4 and IgG was performed in all cases. The mean age of the 30 lesions characterized as FHVHPT was 56 years (range: 23 to 79 y). Nineteen patients showed solitary lesions; 11 were multiple. The mean size of the lesion was 3.8 cm (range: 1 to 7.5 cm). On imaging, a neoplastic process or metastasis was the leading diagnostic consideration (n=15, 50%). The most common symptom was abdominal pain (n=14/30); 8 patients presented with symptoms compatible with an infectious process, including fever. The inflammatory infiltrate was dominated by lymphocytes and plasma cells, and in most cases, a prominent histiocytic infiltrate (22/30). Neutrophils were identified in 12 cases, with microabscess noted in 8. Storiform pattern of fibrosis was seen in 14/30 cases; obliterative phlebitis was not identified. Culture identified a microorganism in 4 of 9 cases evaluated. The mean IgG4 count was 9.3 per HPF (range: 0 to 51) with 9 of the 26 (35%) biopsies showing >10 IgG4 positive plasma cells per HPF. The mean IgG4 to IgG ratio was 8% (range: 8% to 46%). A hepatectomy was performed in 4 cases. On broad spectrum antibiotics (n=14) the lesions either resolved or decreased in size. Eight patients did not receive specific therapy, nevertheless, the lesion(s) resolved spontaneously in 6 cases, remained stable or decreased in size in 2 cases. Notably, none of these patients showed evidence of a hepatic recurrence. FHVHPT, a tumefactive lesion that mimics hepatic neoplasia, is histologically characterized by a fibrohistiocytic infiltrate. In the majority of patients FHVHPT represents the organizing phase of hepatic abscess and can be successfully managed with antibiotic therapy.

中文翻译：

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肝假性肿瘤的纤维组织细胞变异：抗生素反应性肿瘤病变。

炎性假瘤是一个术语，用于指代富含炎症的肿瘤性病变。在排除特定实体（例如 IgG4 相关疾病和先前包含在该实体中的其他肿瘤实体）之后，大多数肝假瘤表现出显着的纤维组织细胞炎症反应，并且先前已被归类为肝假瘤的纤维组织细胞变异（FHVHPT）。本研究的目的是检查该实体的临床、放射学、组织学和病因学方面。在排除肿瘤性疾病后，我们在 2009 年至 2019 年期间从 3 个机构中确定了 30 名 FHVHPT 患者。我们提取了人口统计学和临床​​数据、肝功能检查以及培养结果和放射学信息。审查苏木精和伊红染色的载玻片的炎症模式及其细胞组成。在所有情况下都进行了 IgG4 和 IgG 的免疫组织化学。表征为 FHVHPT 的 30 个病变的平均年龄为 56 岁（范围：23 至 79 岁）。19 名患者表现为孤立性病变；11个是多个。病变的平均大小为 3.8 厘米（范围：1 至 7.5 厘米）。在影像学上，肿瘤过程或转移是主要的诊断考虑因素（n=15, 50%）。最常见的症状是腹痛（n=14/30）；8 名患者出现与感染过程相符的症状，包括发烧。炎症浸润以淋巴细胞和浆细胞为主，在大多数情况下，组织细胞浸润明显(22/30)。在 12 例中发现了中性粒细胞，在 8 例中发现了微脓肿。在 14/30 例中观察到纤维化的层状图案；未发现闭塞性静脉炎。在评估的 9 例病例中，有 4 例培养物鉴定出微生物。每个 HPF 的平均 IgG4 计数为 9.3（范围：0 到 51），26 个活检中有 9 个（35%）显示每个 HPF 的 IgG4 阳性浆细胞 >10 个。IgG4 与 IgG 的平均比率为 8%（范围：8% 至 46%）。4 例行肝切除术。使用广谱抗生素 (n=14) 时，病变消退或缩小。8 例患者未接受特殊治疗，但 6 例病灶自行消退，2 例保持稳定或缩小。值得注意的是，这些患者都没有表现出肝脏复发的证据。FHVHPT 是一种模拟肝脏肿瘤的肿瘤性病变，其组织学特征是纤维组织细胞浸润。