Erythroleukoplakia of the Oral Mucosa

A biopsy of a clinical erythroleukoplakia is made to determine whether dysplasia or invasive carcinoma is present. Because a biopsy is an invasive procedure that may cause inflammatory lymphadenopathy, which would confuse a later TNM (primary tumor, regional nodes, and metastases) classification if carcinoma is found, a brief clinical staging using the TNM classification is done before the biopsy. The biopsy may be taken using local anesthesia. However, a nerve block or field block technique is recommended over local infiltration. Although injecting local anesthetic into the lesion will not spread or seed tumor cells because of the thin needle gauge, the solution volume itself will distort tissue and create artifacts.

The most yielding areas for biopsy are the erythroplakic areas, areas of atrophy, or areas where induration is palpated. Often multiple areas are biopsied and, when practical, the entire clinical lesion excised (Fig 1-8). The experienced clinician may not require biopsy site aids, but toluidine blue may be used to determine the most yielding site for an incisional biopsy. This aid may be of particular value in the biopsy of a clinically homogenous lesion. Toluidine blue is a vital dye that binds to DNA and sulfated mucopolysaccharides in all tissues. However, because actively replicating tissues such as dysplasias and cancers contain elevated levels of each, the blue dye will concentrate in these tissues, thus guiding the clinician to the best site for biopsy (Figs 1-9a and 1-9b). The technique uses a 1% aqueous solution of toluidine blue, which is applied to the lesion and allowed to remain for 1 minute. It is then "decolorized" with 1% acetic acid. The areas of persistent toluidine dye staining are recommended for biopsy.

The area of biopsy should remain within the confines of the clinical lesion. Taking a margin of normal-appearing tissue for this type of biopsy will not assist the microscopic assessment and will only risk extending a tumor margin into uninvolved areas. The biopsy should be sufficiently deep to include underlying muscle. Should a carcinoma in situ or an invasive carcinoma be found, determining the integrity of the basement membrane and the depth of invasion, possibly into muscle tissue, will be important.

Unless the pathologist states a preference for a different fixative, 10% formalin (4% formaldehyde) in a neutral-buffered solution is best. If the specimen is shipped in winter, it should be labeled, "Do not allow to freeze," because freezing will induce artifacts.

Fig 1-8. This lesion can be excised for a complete histopathologic examination. However, if incisional biopsies are used, areas of erythroplakia, atrophy, or indurations are the best sites for sampling.

Fig 1-9a. Suspicious floor-of-the-mouth lesion.

Fig 1-9b. Increased uptake of 1% toluidine blue, implying a greater DNA turnover, indicates the preferred site for an incisional biopsy.