Test Catalog

Test ID: CLAUD    
Claudin-1 Immunostain, Technical Component Only

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

Identification of a number of different soft tissue and epithelial neoplasms

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

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

Claudin proteins are a family of tight junction-associated proteins that prevent leakage of ions, water, etc between cells. Differential expression of claudin proteins is seen in various epithelial cell types. Strong expression of claudin-1 is seen on squamous epithelial cells of the skin. Claudin-1 may have reduced expression in invasive versus benign breast lesions. In the diagnostic setting, 30% to 50% of soft tissue and intramucosal intestinal perineuriomas are positive for claudin-1. Gastric intestinal-type adenocarcinoma shows more frequent claudin-1 expression than diffuse gastric carcinomas.

Interpretation Provides information to assist in interpretation of the test results

This test does not includes pathologist interpretation; only technical performance of the stain. If an 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. Katzka DA, Tadi R, Smyrk TC, et al: Effects of topical steroids on tight junction proteins and spongiosis in esophageal epithelia of patients with eosinophilic esophagitis. Clin Gastroenterol Hepatol. 2014 Nov;12(11):1824-9.e1. doi: 10.1016/j.cgh.2014.02.039

2. Bhat AA, Syed N, Therachiyil L, et al: Claudin-1, a double-edged sword in cancer. Int J Mol Sci. 2020 Jan;21(2):569. doi: 10.3390/ijms21020569

3. Moldvay J, Fabian K, Jackel M, et al: Claudin-1 protein expression Is a good prognostic factor in non-small cell lung cancer, but only in squamous cell carcinoma cases. Pathol Oncol Res. 2017;23(1):151-156. doi: 10.1007/s12253-016-0115-0