A 72-year-old man was referred to our department for evaluation of a white lesion on the right side of the tongue. The lesion had been present for 5 years and appeared as a 4 cm area of plaque-like thickening of the mucosa much whiter than the surrounding tissue (). The patient enjoyed otherwise good health. His personal and family histories were unremarkable. In particular, there was no history of smoking or local trauma and no other oral lesions were detected at clinical examination.
Lesion appearing as a 4 cm area of plaque-like thickening of the mucosa on the right side of the tongue.
A first biopsy, performed at presentation, failed to disclose any dysplastic or malignant features. The lesion had been slightly enlarging during the last 5 years so a further biopsy was performed to exclude the development of dysplasia and to investigate the possibility of any other disease responsible for the white plaque.
The biopsy material was fixed in buffered formalin and paraffin embedded. Serial sections were stained with H&E and periodic acid–Schiff (PAS) stain with and without diastase digestion to highlight the intracytoplasmic glycogen. In addition immunohistochemical staining was performed to disclose possible infection by human papilloma virus (HPV, monoclonal, clone K1HB, diluted 1:100; Thermo Scientific, Waltham, MA, USA). The first biopsy was retrieved and the histological findings compared. Both showed the same histological picture and therefore will be described together.
The histological sections showed thickened squamous epithelium with basal hyperplasia and acanthosis (). The cells of the prickle layer had clear cytoplasm filled with glycogen as demonstrated on PAS staining (). There was no evidence of epithelial dysplasia according to the criteria defined by the WHO blue book.5
No inflammatory infiltration or fungal structures were present. Immunohistochemistry failed to reveal evidence of HPV infection ().
Figure 2 A. Histologically the lesion presented as a slightly raised plaque composed of epithelium with basal cell hyperplasia and clear keratinocytes filled with glycogen (magnification 20×), as demonstrated with periodic acid–Schiff (PAS) stain (more ...)