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Synonyms[]

Antibodies[]

Technical Info[]

Staining Pattern[]

  • Nuclear AND cytoplasmic

Expression in Normal Tissues[]

  • Melanocytes
  • Schwann cells
  • Langerhans cells
  • Other dendritic cells
  • Myoepithelial cells (some)
  • Adipocyte

Expression in Neoplastic Entities[]

Benign[]
Tumor name % Positive Staining (Sensitivity) Number of Cases Specificity Comments
Schwannoma 100%[1] 8/8[1]
Melanocytic nevi
Neurofibroma
Myoepithelioma 100%[2] 13/13[2]
Rosai-Dorfman Disease


Intermediate/Uncertain Malignant Potential[]
Tumor name % Positive Staining (Sensitivity) Number of Cases Specificity Comments
Langerhans cell histiocytosis


Malignant[]
Tumor name % Positive Staining (Sensitivity) Number of Cases Specificity Comments
Chordoma
Melanoma 100%[3] 33/33[3]
Epithelioid Malignant Peripheral Nerve Sheath Tumor (MPNST)
Myoepithelial Carcinoma 100%[4] 25/25[4]

Expression in Non-Neoplastic Entities[]

Pertinent Negatives[]

This antigen is typically negative in the following:

  • Malignant peripheral nerve sheath tumor (MPNST). This is a common misunderstanding among pathologists. Approximately 50% of MPNST are totally negative for S100 protein. Those that are positive usually have only weak, focal, patchy staining. One exception is epithelioid MPNST, a tumor which is typically strongly S100 protein positive.
  • Only focally positive in meningioma with stronger cytoplasmic staining than nuclear staining (schwannoma is strongly and diffusely positive with nuclear staining predominating)[1]

Practical Uses / Panels[]

Common Pitfalls[]

References[]

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