Introduction (简介)
Definition (定义)：
IgG4-related disease (IgG4-RD) is a systemic, immune-mediated fibroinflammatory condition capable of affecting multiple organs.
IgG4相关疾病是一种系统性、免疫介导的纤维炎症性疾病，可累及多个器官。Key Features (主要特点)：
Pathology (病理特点)：Lymphoplasmacytic infiltrates, storiform fibrosis, and obliterative phlebitis.
淋巴浆细胞浸润、车轮状纤维化和闭塞性静脉炎。Serology (血清学)：Elevated serum IgG4 levels in ~60-70% of cases.
血清IgG4水平在约60-70%的病例中升高。Clinical Manifestations (临床表现)：Often presents with painless organ enlargement or mass lesions.
常以无痛性器官肿大或肿块病变为表现。
Epidemiology (流行病学)
Incidence (发病率)：0.78 to 1.39 per 100,000 person-years (2023 data).
每10万人每年0.78至1.39例（2023年数据）。Age and Gender (年龄和性别)：Typically affects individuals aged 50–70 years, with a male predominance (~60–70%).
多见于50-70岁人群，男性略占多数（~60-70%）。
Clinical Features (临床特点)
Organ Involvement (器官累及)：
Most commonly affected: pancreas, salivary glands, bile ducts, retroperitoneum, and kidneys.
常见累及器官：胰腺、唾液腺、胆管、后腹膜、肾脏。Multiorgan involvement occurs in ~60-80% of cases.
多器官累及：约60-80%的病例出现多器官累及。Presenting Symptoms (首发症状)：
Subacute Masses (亚急性肿块)：Painless organ swelling or mass lesion.
无痛性器官肿大或肿块病变。Weight Loss (体重减轻)：Seen in multiorgan disease, often linked to autoimmune pancreatitis.
体重减轻多与多器官病变及自身免疫性胰腺炎有关。Lymphadenopathy (淋巴结肿大)：Non-tender, rubbery lymph nodes.
无压痛、质地橡皮样的淋巴结。Differentiation from Other Diseases (与其他疾病的鉴别)：
Mimics autoimmune diseases (e.g., Sjögren's, GPA), malignancies, and infections.
易与以下疾病混淆：如干燥综合征、肉芽肿性多血管炎（GPA）、恶性肿瘤和感染。
Pathophysiology (发病机制)
Immune Mechanisms (免疫机制)：Driven by dysregulated immune responses, including Th2 polarization and regulatory T-cell activation.
由失调的免疫反应驱动，包括Th2极化和调节性T细胞（Tregs）激活。Histologic Hallmark (组织学特征)：IgG4-positive plasma cells in tissue (>30–50 per HPF in most organs).
组织中存在大量IgG4阳性浆细胞（大多数器官中每高倍视野>30-50个）。
Diagnosis (诊断)
Clinical Suspicion (临床怀疑)：
Unexplained mass, organ swelling, or retroperitoneal fibrosis.
不明原因的肿块、器官肿大或后腹膜纤维化。Serum IgG4 (血清IgG4水平)：
Elevated in ~70% of cases but not diagnostic alone.
约70%的病例中升高，但单独不足以确诊。Biopsy (组织活检)：
Required for definitive diagnosis. Features include lymphoplasmacytic infiltration, storiform fibrosis, and obliterative phlebitis.
活检是确诊的必要手段，需显示淋巴浆细胞浸润、车轮状纤维化及闭塞性静脉炎。Imaging (影像学检查)：
CT/MRI: Diffuse organ enlargement, "sausage-shaped" pancreas, or mass lesions.
CT/MRI可显示器官弥漫性增大（如“香肠样”胰腺）或肿块病变。
Management (治疗)
First-Line Treatment (一线治疗)：
Glucocorticoids: Prednisone 30–40 mg/day, tapered over 3–6 months.
糖皮质激素：泼尼松30–40 mg/天，3–6个月内逐渐减量。Refractory Cases (难治病例)：
Immunosuppressants: Rituximab, azathioprine, or mycophenolate mofetil.
免疫抑制剂：利妥昔单抗、硫唑嘌呤或霉酚酸酯。Surgical Intervention (手术干预)：Reserved for complications (e.g., obstructive uropathy).
仅用于处理并发症（如梗阻性尿路病变）。
Prognosis (预后)
Generally favorable with early treatment, but relapse is common (~40-50%).
早期治疗效果较好，但复发率高（~40-50%）。
Quick Memory Aids (快速记忆法)
Histopathology Triad (组织学三联征)
“淋-轮-闭”
Lymphoplasmacytic infiltrate (淋巴浆细胞浸润).
Storiform fibrosis (车轮状纤维化).
Obliterative phlebitis (闭塞性静脉炎).
Commonly Affected Organs (常累及器官)
“胰唾胆肾后”
Pancreas (胰腺).
Salivary glands (唾液腺).
Sclerosing cholangitis (硬化性胆管炎).
Retroperitoneum (后腹膜).
Kidneys (肾脏).
Pathophysiology Mnemonic (发病机制记忆)
“T2调高IgG4，纤维堵管炎症多”
T2: Th2-driven immune response (Th2驱动免疫反应).
Elevated IgG4 (IgG4水平升高).
Fibrosis, obstruction, and inflammation (纤维化、堵管、炎症多).
Differential Diagnosis Mnemonic (鉴别诊断记忆)
“肿瘤炎症类免疫，干燥肉GPA”
Tumors (肿瘤): e.g., pancreatic cancer, cholangiocarcinoma (胰腺癌、胆管癌).
Inflammation (炎症): e.g., granulomatosis with polyangiitis (GPA, 肉芽肿性多血管炎).
Autoimmune conditions (类免疫病): e.g., Sjögren’s syndrome (干燥综合征).
Histopathology Triad (组织学三联征):
"Lymph-Stor-Oblit"Lymphoplasmacytic infiltrate (淋巴浆细胞浸润).
Storiform fibrosis (车轮状纤维化).
Obliterative phlebitis (闭塞性静脉炎).
Commonly Affected Organs (常累及器官):
"PSS-Liver-Kidney"Pancreas (胰腺).
Salivary glands (唾液腺).
Sclerosing cholangitis (硬化性胆管炎).
Differential Diagnosis Red Flags (鉴别诊断标志):
"FAST"Fever (发热): Unusual in IgG4-RD.
Autoantibodies (自身抗体): Suggest other autoimmune diseases.
Specific mass features (特定肿块特征): Malignancy-like.
Tumor growth speed (快速肿瘤生长): Infections/malignancies.
