Pathological Findings of IgG4-Related Lung Disease
IgG4-related disease (IgG4-RD) causes temporally and spatially diverse lesions in systemic organs, with respiratory organ involvement now known to include the bronchi, bronchioles, alveolar wall, pleura, pulmonary vessels, and mediastinal lymph nodes. The
- PDF / 603,610 Bytes
- 5 Pages / 595.28 x 790.87 pts Page_size
- 45 Downloads / 223 Views
24
Shoko Matsui, Kenji Notohara, and Yuko Waseda
24.1
Introductory Remarks
IgG4RD is known to cause tumefactive lesions in almost all organs of the body including the pituitary gland, lacrimal gland, submandibular gland, pancreas, bile duct, kidney, retroperitoneum, aorta, and prostate. In the respiratory organs, too, diverse lesions are now known to develop at numerous sites including the mediastinal lymph nodes, bronchi, peribronchovascular sheath, alveolar septa, and pleura. However, in contrast to type 1 autoimmune pancreatitis (AIP), characteristic histopathological findings in the lung are few, and the diagnosis of IgG4related lung disease (IgG4-RLD) can be difficult to render with certainty. In this chapter, we outline the lesions seen in IgG4RLD, focusing on their histopathological features.
24.2
Clinical Characteristics of IgG4-RLD
IgG4-RLD occurs most commonly in middle-aged and elderly men. It is estimated to be present in about 10 % of all cases of IgG4-RD, although its frequency has not yet been accurately determined. Because respiratory organ lesions often produce few subjective symptoms, they are frequently detected during a workup for other organ lesions or an abnormal chest shadow. They may also present with asthmatic symptoms such as cough or wheezing and are therefore susceptible to misdiagnosis as bronchial asthma.
S. Matsui (*) Health Administration Center, University of Toyama, 2630 Sugitani, Toyama city, Toyama 930-0194, Japan e-mail: [email protected] K. Notohara Department of Anatomic Pathology, Kurashiki Central Hospital, Kurashiki, Japan Y. Waseda Department of Respiratory Medicine, Kanazawa University School of Medicine, Kanazawa, Japan
Laboratory abnormalities in IgG4-RLD include extremely elevated serum IgG and IgG4 values. Serum IgG4 values >135 mg/dL raise a suspicion of IgG4-RD. Among the 13 cases with IgG4-RLD evaluated in our combined experience, the mean serum IgG concentration was 3,930 mg/dL (normal: 863–1,589 mg/dL) and the mean serum IgG4 concentration was 1,347 mg/dL (normal: 4–108 mg/dL). These values represent substantial elevations over the values observed in patients with IgG4-RD whose lesions are limited to the lacrimal or salivary glands [1]. Autoantibodies such as rheumatoid factor and antinuclear antibodies are present in 30–40 % of patients with IgG4-RLD, but to date no autoantibody specific to IgG4-RD has been identified. Serum complement protein concentrations (i.e., the CH50, C3, and C4) tend to be low. The erythrocyte sedimentation rate is often elevated from modest to high levels—probably as a consequence of the excessive concentrations of immunoglobulins—but the C-reactive protein is typically within normal limits or elevated to only a mild degree. The reader is referred to another chapter in this book (Imaging: Lung lesions) for an outline of the chest CT findings of IgG4-RLD, which reflect the lesions being formed at various sites. The radiology of IgG4-RLD is complex because diverse findings can be intermingled in a single case.
24.3
His
Data Loading...
