Lip Granular Cell Tumor (GCT) in a Pediatric Patient: Critical Literature Review on Pediatric Intraoral GCT and Acquired and Congenital Intraoral Non-Neural GCT.

Granular cell tumor (GCT) is an uncommon benign neoplasm derived from Schwann cells, frequently affecting the oral cavity, skin, and gastrointestinal tract. On microscopy, pseudocarcinomatous squamous hyperplasia (PSH) and perineural involvement are potential diagnostic pitfalls. GCT should be differentiated from non-neural GCT (NN-GCT). A 13-year-old male patient was referred presenting a nodular lesion on the upper lip several months ago. After excisional biopsy, microscopy revealed GCT without PSH but presenting multifocal perineural involvement. By immunohistochemistry, ALK was negative, whereas Rb and INI1 expression was intact. Moreover, with few intraoral NN-GCTs being assessed, recent studies suggest that acquired dermal NN-GCT subgroup seems to correspond to ALK-rearranged variants of epithelioid fibrous histiocytoma. Accordingly, further research on this topic is strongly encouraged.