Test Catalog

Test ID: CALPN    
Calponin Immunostain, Technical Component Only

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

Marker for myoepithelium when differentiating ductal carcinomas in situ from infiltrating breast carcinoma


Characterization of tumors of smooth muscle or myoepithelial lineage

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

Calponin is a cytoskeleton-associated protein that can bind to actin, tropomyosin, troponin C, and calmodulin and is involved in modulation of smooth muscle contraction.


Calponin expression has been demonstrated in smooth muscle cells of blood vessels and myoepithelial cells in the lobules, ducts, and galactophorous sinuses of normal human breast.

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. Russell T D, Jindal S, Agunbiade S, et al: Myoepithelial cell differentiation markers in ductal carcinoma in situ progression.  Am J Pathol. 2015;185(11):3076-3089. doi: 10.1016/j.ajpath.2015.07.004

2. Gray E, Mitchell, E, Jindal S, Schedin P, Chang YH: A method for quantification of calponin expression in myoepithelial cells in immunohistochemical images of ductal carcinoma in situ. Proc IEEE Int Symp Biomed Imaging. 2018 Apr;2018:796-799. doi: 10.1109/isbi.2018.8363692

3. Liu R, Jin JP: Calponin isoforms CNN 1, CNN 2 and CNN 3: Regulators for actin cytoskeleton functions in smooth muscle and non-muscle cells. Gene. 2016;585(1):143-153. doi: 10.1016/j.gene.2016.02.040