In situ carcinoma developed over oral lichen planus: a case report with analysis of BUB3, p16, p53, Ki67 and SOX4 expression

Abstract

Oral lichen planus (OLP) represents a common mucocutaneous disease. Various authors have suggested that OLP has malignant potential; however, the mechanisms involved in malignant transformation have not yet been elucidated. A 79-year-old man presented a white lesion for five months in the buccal mucosa diagnosed as OLP. After two months using 0.05% clobetasol ointment for treatment, the lesion became ulcerated. A new biopsy of the same lesion was performed, and histological analysis showed an in situ oral carcinoma (ISOC). An immunohistochemistry panel was performed, and p16 expression was negative in OLP, however, it showed weak cytoplasmic staining in ISOC. There was strong nuclear BUB3 staining in both OLP and ISOC areas. p53 showed less intense nuclear staining in both regions. Ki67 was negative in OLP area, but showed nuclear staining in the ISOC. SOX4 was negative in both studied areas. BUB3 expression, first reported in this case, and the p16 expression may suggest some influence of these genes on pathogenesis or malignant potential of OLP.

Figure 1. Clinical aspect of the right buccal mucosa: ulcer with an erythematous halo and small white plaques in the center of the picture

Figure 2. Histological appearance [Hematoxylin & eosin, 100X (a), 400X (b)]: a) band-like lymphocytic infiltrate in the lichenoid area; b) Carcinoma in situ showing several changes from basal layer to upper layer of epithelium. The following alterations are present: cells with enlarged nuclei, pleomorphic cells, hyperchromatism, increased nuclear-to-cytoplasmic ratio, loss of epithelium stratification and basal cell hyperplasia

Figure 3. Immunohistochemistry (400X): p16 nuclear and cytoplasmic staining basal and suprabasal layers – oral lichen planus (OLP) area (a); p16 nuclear and cytoplasmic staining basal and suprabasal layers – in situ oral carcinoma (ISOC) area (b); BUB3 nuclear staining - OLP area (c); BUB3 nuclear staining - ISOC area (d); p53 nuclear staining - OLP area (e); p53 nuclear staining - ISOC area (f); Ki67 negative - OLP area (g); Ki67 nuclear staining basal and suprabasal layers - ISOC area (h)