Department of Pathology, Upstate Medical University, Syracuse, NY.
Departments of Pathology.
Am J Surg Pathol. 2019 Jul;43(7):898-906. doi: 10.1097/PAS.0000000000001282.
Autoimmune pancreatitis (AIP) encompasses a heterogenous disease group that includes IgG4-related type 1 AIP and non-IgG4-related type 2 AIP. Clinically and on imaging, type 2 AIP mimics type 1 AIP, other forms of chronic pancreatitis and pancreatic ductal adenocarcinoma (PDAC); therefore, discriminatory markers may aid proper diagnosis. Herein, we examine the expression of PD-L1 and indoleamine 2,3-dioxygenase (IDO1) as a diagnostic tool to distinguish type 2 AIP from other forms of pancreatitis and PDAC.
We evaluated 35 pancreatectomy specimens diagnosed with type 2 AIP and potential mimics of this disease including type 1 AIP (n=14), chronic pancreatitis-not otherwise specified (n=10), groove pancreatitis (n=14), and PDAC (n=278). We scored inflammatory infiltrates, fibrosis and atrophy and performed immunohistochemical staining for PD-L1 and IDO1. We validated our findings on a series of endoscopic ultrasound-guided biopsies from patients with suspected type 2 AIP and inflammatory and neoplastic mimics of this disease (n=37).
The mean age of patients with type 2 AIP was 50 years with a F:M ratio of 1.2:1. Patients with type 2 AIP showed pancreatic ductal staining for PD-L1 and IDO1 in 69% (24/35) and 60% (15/25) of cases, respectively. PD-L1 reactivity was noted in 3% of patients with other forms of chronic pancreatitis and 3% of PDACs; notably, peritumoral ducts and acini were negative. Eight of 9 endoscopic ultrasound-guided biopsies with pancreatic ductal epithelium from patients with type 2 AIP were positive for PD-L1, while the inflammatory and neoplastic mimics were negative. Collectively, the sensitivity and specificity of PD-L1 as a marker of type 2 AIP was 70% and 99%, respectively.
Ductal PD-L1 reactivity has the potential to distinguish type 2 AIP from other forms of pancreatitis and PDAC.
自身免疫性胰腺炎（AIP）包括一组异质性疾病，包括 IgG4 相关的 1 型 AIP 和非 IgG4 相关的 2 型 AIP。在临床和影像学上，2 型 AIP 类似于 1 型 AIP、其他形式的慢性胰腺炎和胰腺导管腺癌（PDAC）；因此，鉴别标志物可能有助于正确诊断。在此，我们研究了 PD-L1 和吲哚胺 2,3-双加氧酶（IDO1）的表达，作为区分 2 型 AIP 与其他形式胰腺炎和 PDAC 的诊断工具。
我们评估了 35 例经胰切除术标本，这些标本被诊断为 2 型 AIP 及该病的潜在类似物，包括 1 型 AIP（n=14）、非特指性慢性胰腺炎（n=10）、沟状胰腺炎（n=14）和 PDAC（n=278）。我们对炎症浸润、纤维化和萎缩进行评分，并进行 PD-L1 和 IDO1 的免疫组织化学染色。我们在一系列经内镜超声引导活检的疑似 2 型 AIP 患者和该病的炎症和肿瘤类似物（n=37）中验证了我们的发现。
2 型 AIP 患者的平均年龄为 50 岁，男女比例为 1.2:1。2 型 AIP 患者的胰腺导管 PD-L1 和 IDO1 染色阳性率分别为 69%（24/35）和 60%（15/25）。其他形式的慢性胰腺炎和 3%的 PDAC 患者中可见 PD-L1 反应性；值得注意的是，肿瘤周围导管和腺泡为阴性。9 例经内镜超声引导活检的患者，其胰腺导管上皮均为 2 型 AIP 阳性，而炎症和肿瘤类似物均为阴性。总的来说，PD-L1 作为 2 型 AIP 标志物的敏感性和特异性分别为 70%和 99%。
导管 PD-L1 反应性有可能将 2 型 AIP 与其他形式的胰腺炎和 PDAC 区分开来。
