Granular Cell Tumour Histology — ORE Part 1 MCQ

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HardOral PathologyGranular Cell Tumour HistologyORE Part 1

A 28-year-old patient presents with a painless, firm, sessile nodule on the dorsum of the tongue, approximately 1 cm in diameter. It has been present for several years and has not changed. It is covered with normal mucosa. Biopsy shows large polygonal cells with abundant granular eosinophilic cytoplasm. Immunohistochemistry is positive for PAS and S-100 protein. What is the diagnosis?

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Correct answer: D — Granular cell tumour

Granular cell tumour (GCT) is confirmed by the pathognomonic combination of clinical presentation and immunohistochemistry. The dorsal tongue location, painless, slow-growing nodule with normal mucosa, and polygonal cells with abundant eosinophilic granular cytoplasm are classic. S-100 positivity indicates neural origin (Schwann cell); PAS positivity reflects lysosomal glycogen. Together, these stains discriminate GCT from neurofibroma (spindle cells, less granular appearance), fibroma (no granular cytoplasm, S-100 and PAS negative), and muscle-derived tumours (rhabdomyoma and leiomyoma would show desmin/myogenin and actin positivity, not Schwann cell markers). GCT is benign; malignancy is rare (<2%) and requires atypical features (high mitotic rate, pleomorphism, necrosis).

Reference: Lafuente-Ibáñez de Mendoza I et al. Oral granular cell tumour: A multicentric study of 56 cases and a systematic review. Med Oral Patol Oral Cir Bucal. 2020. https://pubmed.ncbi.nlm.nih.gov/31898368/