Test Catalog

Test ID: BFOS    
FosB, Immunostain, Technical Component Only

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

Diagnosing pseudomyogenic (epithelioid sarcoma-like) hemangioendothelioma (PHE) and epithelioid hemangiomas

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

FosB is a member of the Fos transcription factor family and a component of the activator protein-1 (AP-1) protein complex. Expressed in the nucleus, FosB is useful in the diagnosis of pseudomyogenic (epitheliod sarcoma-like) hemangioendothelioma (PHE) and may be helpful to distinguish it from its histologic mimics. FosB is also found in a subset of epithelioid hemangiomas.

Interpretation Provides information to assist in interpretation of the test results

The positive and negative controls are verified as showing appropriate immunoreactivity. If a control tissue is not included on the slide, a scanned image of the relevant quality control tissue is available upon request. Contact 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

No significant cautionary statements

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

1. Hung YP, Fletcher CD, Hornick JL: FOSB is a Useful Diagnostic Marker for Pseudomyogenic Hemangioendothelioma. Am J Surg Pathol 2017;41:596-606

2. Sugita S, Hirano H, Kikuchi N, et al:  Diagnostic utility of FOSB immunohistochemistry in pseudomyogenic hemangioendothelioma and its histological mimics. Diagn Pathol 2016;11:75 doi 10.1186/s13000-016-0530-2

3. Huang SC, Zhang L, Sung YS, et al: Frequent FOS Gene Rearrangements in Epithelioid Hemangioma: A Molecular Study of 58 Cases with Morphologic Reappraisal. Am J Surg Pathol 2015;39(10):1313-1321