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Test ID: IGG4I    
IgG4 Immunostain, Technical Component Only

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Useful For Suggests clinical disorders or settings where the test may be helpful

Identification of IgG4-positive plasma cells in the tissue of patients with systemic autoimmune or allergic manifestations

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

For the initial technical component only immunohistochemical (IHC) stain performed, the appropriate bill-only test ID will be reflexed and charged (IHTOI). For each additional technical component only IHC stain performed, an additional bill-only test ID will be reflexed and charged (IHTOA).

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Immunoglobulin G4 is the least abundant of IgG subclasses, normally comprising 6% of total IgG. Elevated serum IgG4 levels may be associated with localized or systemic allergic and autoimmune manifestations, such as inflammatory pseudotumor in liver, breast, and lung, sclerosing pancreatitis, and pemphigus vulgaris. In these disease states, increased numbers of IgG4-positive plasma cells are present in the tissue.

Interpretation Provides information to assist in interpretation of the test results

This test does not include pathologist interpretation, only technical performance of the stain. If interpretation is required order PATHC / Pathology Consultation for a full diagnostic evaluation or second opinion of the case.

 

The positive and negative controls are verified as showing appropriate immunoreactivity and documentation is retained at Mayo Clinic Rochester. If a control tissue is not included on the slide, a scanned image of the relevant quality control tissue is available upon request; call 855-516-8404.

 

Interpretation of this test should be performed in the context of the patient's clinical history and other diagnostic tests by a qualified pathologist.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Age of a cut paraffin section can affect immunoreactivity. Stability thresholds vary widely among published literature and are antigen dependent. Best practice is for paraffin sections to be cut within 6 weeks.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. Heidarpour M, Rajabi P, Pour EB, Fayyazi E: Immunohistochemistry for immunoglobulin G4 in the diagnosis of pemphigus. Indian J Dermatol. 2019 Jul-Aug;64(4):338. doi: 10.4103/ijd.IJD_87_18

2. Chen LYC, Mattman A, Seidman MA, Carruthers MN: IgG4-related disease: what a hematologist needs to know. Haematologica. 2019 Mar;104(3):444-455. doi: 10.3324/haematol.2018.205526

3. Miyabe K, Zen Y, Cornell LD, et al: Gastrointestinal and extra-intestinal manifestations of IgG4-related disease. Gastroenterology. 2018 Oct;155(4):990-1003.e1. doi: 10.1053/j.gastro.2018.06.082