Chougule Abhijit, Bal Amanjit, Das Ashim, Agarwal Ritesh, Singh Navneet, Rao Katragadda L N
Departments of *Histopathology †Pulmonary Medicine ‡Paediatric Surgery, Post Graduate Institute of Medical Education and Research (PGIMER), Chandigarh, India.
Appl Immunohistochem Mol Morphol. 2016 Nov/Dec;24(10):721-728. doi: 10.1097/PAI.0000000000000252.
IgG4-related disease is a recently recognized systemic condition characterized by tumefactive lesions at various sites. Inflammatory pseudotumor (IPT), a tumefactive mass lesion with an unknown etiology, belongs to the spectrum of IgG4-related disease. Inflammatory myofibroblastic tumor (IMT), previously considered under the umbrella of IPT, is now classified as a clonal neoplasm. Previously, both the terms were used interchangeably, because of overlapping morphologic features. This study was carried out to compare the morphologic and the immunohistochemical features of these entities and to study the role of IgG4 in their pathogenesis. Thirty-nine cases comprising of IMT (n=18) and IPT (n=21) were retrieved, and their clinical, morphologic, and immunohistochemical features were studied. IMT was more common in children as compared with IPT. IMT cases showed the proliferation of myofibroblastic cells accompanied by a variable inflammatory infiltrate, whereas IPT cases showed predominantly stromal fibrosis and a lymphoplasmacytic infiltrate with a subset of cases showing a storiform fibrosis and obliterative phlebitis. Anaplastic lymphoma kinase-1 (ALK-1) was positive in 12 of the 18 (66.7%) IMT cases, whereas none of the IPT cases showed ALK-1 immunoreactivity. IPT cases showed significantly increased IgG4+ plasma cells (mean, 127.8/high-power fields vs. 17.8/high-power fields) and a higher IgG4/IgG ratio (mean, 48.2% vs. 10.7%) as compared with IMT. Fluorescence in situ hybridization analysis was positive for ALK rearrangement in 6 of the 9 IMT cases tested. In conclusion, most of the IPT cases can be considered as IgG4 related on the basis of their histopathologic features and immunohistochemistry criteria. However, IMT represents a myofibroblastic neoplasm with ALK-1 overexpression and is clearly not IgG4 related.
IgG4相关性疾病是一种最近才被认识的全身性疾病，其特征是在各个部位出现肿块样病变。炎性假瘤（IPT）是一种病因不明的肿块样病变，属于IgG4相关性疾病的范畴。炎性肌成纤维细胞瘤（IMT）以前被认为属于IPT，现在被归类为一种克隆性肿瘤。以前，由于形态学特征重叠，这两个术语可以互换使用。本研究旨在比较这些实体的形态学和免疫组化特征，并研究IgG4在其发病机制中的作用。收集了39例病例，包括IMT（n = 18）和IPT（n = 21），并对其临床、形态学和免疫组化特征进行了研究。与IPT相比，IMT在儿童中更常见。IMT病例显示肌成纤维细胞增殖并伴有不同程度的炎性浸润，而IPT病例主要表现为间质纤维化和淋巴浆细胞浸润，部分病例表现为席纹状纤维化和闭塞性静脉炎。间变性淋巴瘤激酶-1（ALK-1）在18例IMT病例中的12例（66.7%）呈阳性，而IPT病例均未显示ALK-1免疫反应性。与IMT相比，IPT病例显示IgG4+浆细胞显著增加（平均，127.8/高倍视野 vs. 17.8/高倍视野），且IgG4/IgG比值更高（平均，48.2% vs. 10.7%）。在9例检测的IMT病例中，6例荧光原位杂交分析ALK重排呈阳性。总之，根据组织病理学特征和免疫组化标准，大多数IPT病例可被认为与IgG4相关。然而，IMT是一种伴有ALK-1过表达的肌成纤维细胞肿瘤，显然与IgG4无关。
