Ledet S C, Brown R W, Cagle P T
Department of Pathology, Baylor College of Medicine, Houston, Texas, USA.
Mod Pathol. 1995 Apr;8(3):282-6.
Inflammatory pseudotumor (IPT) of the lung is a non-neoplastic process that consists of proliferating spindle cells (fibroblasts and myoblasts), with variable numbers of mitoses, and inflammatory cells, particularly plasma cells. These lesions clinically, radiographically, and grossly mimic malignant neoplasms but are usually easily distinguished from malignancy on routine histopathology. However, in occasional cases the proliferating spindle cells may histopathologically mimic sarcoma, particularly on small biopsies and needle aspirates. Strong intranuclear immunopositivity for p53 protein is presumed to be indirect evidence of mutation of the p53 tumor suppressor gene and can be detected in many malignancies. In order to determine the utility of p53 immunostaining in differentiating IPT occurring in the lung from sarcoma involving the lung, we immunostained eight solitary IPTs, one IPT that recurred repeatedly over a 10-year period, six sarcomas (two malignant fibrous histiocytomas, two metastatic high-grade sarcomas, one metastatic alveolar soft part sarcoma, and one fibrosarcoma) involving the lung, and one IPT from which a sarcoma arose 10 years after radiation therapy. Immunohistochemistry was performed on 5-microns formalin-fixed sections using a commercially available antibody to the p53 protein (Biogenex, monoclonal 1:200) and a standard antigen retrieval technique. Weak intranuclear staining occurring in less than 10% of proliferating cells was not considered a true immunopositive. All eight of the solitary IPTs were immunonegative for p53 protein by our criteria. The IPT that recurred a number of times and the IPT from which a sarcoma later developed were also immunonegative for p53 protein. Four of the six sarcomas were immunopositive, as was the postradiation sarcoma arising from a p53-immunonegative IPT.(ABSTRACT TRUNCATED AT 250 WORDS)
肺炎性假瘤（IPT）是一种非肿瘤性病变，由增生的梭形细胞（成纤维细胞和平滑肌母细胞）组成，有数量不等的核分裂象，还有炎症细胞，尤其是浆细胞。这些病变在临床、影像学及大体表现上可类似恶性肿瘤，但在常规组织病理学上通常很容易与恶性肿瘤区分开来。然而，在少数情况下，增生的梭形细胞在组织病理学上可能类似肉瘤，尤其是在小活检标本和针吸活检中。p53蛋白强核内免疫阳性被认为是p53肿瘤抑制基因突变的间接证据，在许多恶性肿瘤中都能检测到。为了确定p53免疫染色在鉴别肺IPT与累及肺的肉瘤中的作用，我们对8例孤立性IPT、1例在10年内反复复发的IPT、6例累及肺的肉瘤（2例恶性纤维组织细胞瘤、2例转移性高级别肉瘤、1例转移性肺泡软组织肉瘤和1例纤维肉瘤）以及1例放疗10年后发生肉瘤的IPT进行了免疫染色。使用市售的针对p53蛋白的抗体（Biogenex，单克隆抗体，1:200）和标准抗原修复技术，对5微米厚的福尔马林固定切片进行免疫组织化学检测。增生细胞中不到10%出现的弱核内染色不被视为真正的免疫阳性。根据我们的标准，所有8例孤立性IPT对p53蛋白均为免疫阴性。多次复发的IPT以及后来发生肉瘤的IPT对p53蛋白也为免疫阴性。6例肉瘤中有4例为免疫阳性，放疗后由p53免疫阴性的IPT发生的肉瘤也为免疫阳性。（摘要截短至250字）
