Granular cell tumor of the oral cavity: updated immunohistochemical profile

Background:  Granular cell tumor (GCT) is a benign lesion that occurs at different body sites with preponderance to the oral cavity. It is generally believed to be of schwann cell/neural cell origin. We used a large panel of both traditional and recently developed antibodies in an attempt to trace the origin of GCTs on the basis of their immunoprofile.
Methods:  The patients' demographic data and the cytological and architectural features of the lesions were analyzed in a large series of oral GCTs ( n  = 68). Forty-two lesions were also submitted to a panel of immunohistochemical stains with antibodies against S-100, CD-68 (KP-1 and PG-M1), vimentin, calretinin, NKI/C3, PGP9.5, p75/NGFR and inhibin-α.
Results:  The tongue was the most common location of oral GCTs (81%). The granular cells demonstrated a wide array of cytological features in terms of cell shape and position of the nucleus. In addition, the lesions showed different architectural patterns, including 'infiltration' with satellite nodules. Interestingly, no recurrences were reported, even in lesions that were not completely excised. Granular cells were usually found to be strongly and diffusely positive for p75, vimentin, calretinin and NKI/C3, inhibin-α, PGP9.5, and S-100.
Conclusions:  Immunoreactivity of the granular cells to a broad panel of antibodies that characterize different tissues does not confirm any particular cell type for the histogenetic origin of GCTs. Furthermore, GCTs could be regarded as lesions that reflect a local metabolic or reactive change rather than a true neoplasm.