Desmin by IHC

Desmin by IHC

Test Name: Desmin Immunohistochemistry (IHC)
Specimen: Tissue biopsy / formalin-fixed paraffin-embedded (FFPE) tissue
Method: Immunohistochemistry

About the Test

Desmin is an intermediate filament protein expressed mainly in skeletal, cardiac, and smooth muscle cells. Desmin IHC is used as a myogenic differentiation marker to help identify tumors showing muscle-lineage differentiation.

Clinical Indications

Desmin IHC may be useful in:

• Evaluation of soft tissue tumors
• Suspected rhabdomyosarcoma
• Suspected leiomyoma or leiomyosarcoma
• Characterization of poorly differentiated or spindle-cell tumors
• Determining whether a tumor demonstrates muscle differentiation

Test Interpretation

• Positive: Cytoplasmic staining supports muscle/myogenic differentiation.
• Negative: Makes myogenic differentiation less likely, but does not by itself exclude a tumor of muscle origin.
• Desmin should generally be interpreted along with morphology and other markers such as SMA, h-caldesmon, Myogenin and MyoD1, depending on the diagnostic question.

Important Note

Desmin is not completely specific for a particular muscle tumor and can occasionally be expressed in other lesions or non-neoplastic myofibroblastic cells. Therefore, the result should be interpreted as part of an appropriate IHC panel by a qualified pathologist.

Why it matters: Desmin IHC helps pathologists establish muscle-lineage differentiation, supporting the diagnosis and classification of selected soft tissue tumors.