I often hear the term “low threshold” when it comes to diagnosis of oral dysplasias. Oral dysplasias are tricky especially if you don’t have a clinical image to guide you.

We are all familiar with the usual cytologic features of dysplasia such as pleomorphic cells, pleomorphic nuclei, hyperchromatic nuclei, abnormal mitoses and so forth. In the oral mucosa, it is just as important to evaluate architectural features of dysplasia.
The most common of this is atypical verrucous or papillary epithelial hyperplasia even if there is no or minimal evidence of cytologic dysplasia. There are a limited number of lesions in the oral cavity that are benign and these include:
[indent=1]· Papilloma[/indent]
[indent=1]· Condyloma[/indent]
[indent=1]· Papillary epithelial hyperplasia from denture irritation[/indent]
[indent=1]· Verruciform xanthoma[/indent]
[indent=1]· So-called “juvenile spongiotic gingival hyperplasia” which is almost always papillary[/indent]
[indent=1]· Reactive papillary epithelial hyperplasia from friction (morsicatio mucosae oris and benign alveolar ridge keratosis)[/indent]

Other papillary squamous proliferations not falling into these categories should be viewed with suspicion, especially if the lesions present at high risk sites such as the ventral tongue, floor of mouth, soft palate and gingiva and especially if the clinician provides a clinical diagnosis of “verrucous leukoplakia”.

Another is bulky endophytic squamous proliferation. These tend to be signed out as just epithelial hyperplasia. Some of these already represent bluntly invasive squamous cell carcinomas. The features to look for include:
[indent=1]· Bulky, endophytic pushing rete ridges below the level of the adjacent epithelium (if you have normal with which to compare)[/indent]
[indent=1]· Tips of rete ridges pushing against underlying structures such as periosteum and muscle[/indent]
[indent=1]· Presence of keratin pearls at the tips of rete ridges[/indent]
[indent=1]· Presence of micro-abscesses at the tips of rete ridges[/indent]
[indent=1]· Lack of or minimal inflammatory changes in the epithelium such as spongiosis and leukocyte exocytosis[/indent]
[indent=1]· Keratinocytes with “glassy” cytoplasm[/indent]
[indent=1]· Often a papillary surface[/indent]

I often ask the contributing clinician to send a photograph of the case and most of these as you can imagine, are thick plaques or obvious mass lesions. These should be signed out as “bulky atypical endophytic squamous proliferation” and if appropriate with a note that this may represent an early bluntly invasive squamous cell carcinoma.