Best practices in diagnostic immunohistochemistry: spindle cell neoplasms of the gastrointestinal tract.

BACKGROUND

The proper classification of spindle cell neoplasms of the gastrointestinal tract frequently requires the use of immunohistochemistry, as the histologic appearance of these lesions often overlaps.

OBJECTIVE

To review the antibodies used in the diagnosis of spindle cell neoplasms of the gastrointestinal tract, and to outline an approach to the evaluation of these lesions by using immunohistochemistry.

METHODS

The authors' experience and a review of the English literature from 1976 to 2008.

CONCLUSIONS

The most common spindle cell neoplasm of the gastrointestinal tract is gastrointestinal stromal tumor; this lesion is readily diagnosed with c-kit immunohistochemistry in most cases. Other stains, such as smooth muscle actin, desmin, S100 protein, and beta-catenin, are also useful in the diagnosis of smooth muscle tumors, schwannomas, desmoid-type fibromatoses, and metastatic melanoma.