Utility of Nestin immunohistochemistry in the diagnosis of granular cell tumor

Aim: Granular cell tumors (GCTs) show neuroectodermal differentiation. Morphologically, a wide variety of mesencymal tumors may have granular cell appearance. Nestin, which is an intermediate filament protein expressed in undifferentiated cells during central nerves system development and its tumors. We aim to determine the diagnostic utility of Nestin in diagnosis of GCTs. Methods: Nestin immunohistochemistry applied to GCT cases and other mesenchymal tumors which may have granular cytoplasm and the major differential diagnostic consideration of GCT. A total of 21 GCT from different tissues (including 7 in the esophagus, 8 originating from skin tissues, 4 in the tongue, 2 in the vocal cord), 17 gastrointestinal stromal tumor in the gastrointestinal tract, 8 leiomyoma (5 in the esophagus and 3 originating from skin tissues), 4 schwannoma (1 in the esophagus and 3 originating from skin tissues), subcutaneous mesenchymal tumors ( including 7 neurofibroma, 5 fibroma, 15 dermatofibroma), 20 melanocytic nevi, 15 gastric xanthomas and 15 xanthalesma of the skin were included the study. Results: Nestin positivity was detected in all GCTs. Additionally, strong Nestin positivity was seen in all gastrointestinal stromal tumors, schwannoma and neurofibroma cases. However, Nestin was negative in all leiomyoma, fibroma, dermatofibroma, melanocytic nevi, gastric xanthoma and xanthalesma cases. Conclusion: The study showed that Nestin immunohistochemistry has limitation in distinction of GCT from tumors arising from neural cell lineage such as gastrointestinal stromal tumor, schwannoma and neurofibroma; however, Nestin as a neural marker provides an evidence to neural origin of GCT and could be useful in distinction GCT from other mesenchymal tumors with granular cytoplasm such as leiomyoma, dermatofibroma and melanocytic nevi