Test Catalog

Test ID: SMOTH    
Smoothelin Immunostain, Technical Component Only

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

Distinguishing muscularis mucosae from muscularis propria

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

Smoothelin is a smooth muscle-specific marker expressed only in terminally differentiated smooth muscle cells as part of the cytoskeleton. It is expressed normally in the smooth muscle of the muscularis of the bowel as well as in smooth muscle in other organs.

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. Paner GP, Brown JG, Lapetino S, et al: Diagnostic use of antibody to smoothelin in the recognition of muscularis propria in transurethral resection of urinary bladder tumor (TURBT) specimens. Am J Surg Pathol. 2010;34(6):792-799

2. Miyamoto H, Sharma RB, Illei PB, Epstein JI: Pitfalls in the use of smoothelin to identify muscularis propria invasion by urothelial carcinoma. Am J Surg Pathol. 2010;34(3):418-422

3. Bovio IM, AlQuran SZ, Rosser CJ, Algood CB, Drew PA, Allan RW: Smoothelin immunohistochemistry is a useful adjunct for assessing muscularis propria invasion in bladder carcinoma. Histopathology. 2010;56:951-956

4. Paner GP, Shen SS, Lapetino S, et al: Diagnostic utility of antibody to smoothelin in the distinction of muscularis propria from muscularis mucosae of the urinary bladder. Am J Surg Pathol. 2009;33(1):91-98