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Oral Lichen Planus: The More We Learn, The Less Sure We Are of What We Know

November 25, 2014
Robert J. Achterberg, DDS, MS

Robert J. Achterberg, DDS, MS

Lichen planus is a relatively common, chronic skin disease that often involves the oral mucosa. Although the etiology is still unknown, current evidence indicates that this is an immunologically mediated disorder that primarily affects basal and parabasal epithelial cells. This condition was first described as a distinct entity over 130 years ago. Since that time, numerous articles have appeared in both the dermatologic and dental literature defining and refining the clinical and histopathologic aspects of lichen planus.

In their classic 1961 article entitled “The Oral Lesions of Lichen Planus,”Gerald Shklar, D.D.S., M.S. and Philip L. McCarthy, M.D. presented diagnostic criteria that are still used today by most experienced clinicians and pathologists. Clinically, there are two main forms of oral lichen planus: 1) Reticular and 2) Erosive.  Microscopically, mucosal lesions that exhibit most, if not all, of the classically described histopathologic features are diagnosed as lichen planus. Those lesions exhibiting only a few of the pathologic criteria usually receive a pathologic diagnosis of chronic lichenoid mucositis.

Fast forward to today. The once fairly straightforward diagnostic criteria for oral lichen planus are no longer quite so straightfor ward. It is now well known that there are a growing number of patients who present clinically with white reticular lesions (striae of Wickham) but do not have lichen planus. To make matters worse, biopsy specimens from these patients exhibit findings that are histopathologically indistinguishable from true lichen planus. What are the primary causes of these “lichen planusoid” lesions?

1) Drug reactions… The list of medications implicated in lichenoid drug reactions is long and constantly changing. A fairly current list is presented in the accompanying table from Burket’s Oral Medicine text.

2) Dental restorative materials… Amalgam and gold are the two main offenders.

3) Food/oral hygiene products… especially cinnamon or mint flavored candies, chewing gum, mouthwashes, toothpastes, breath fresheners, etc.

So what’s the current take home message? In order for the oral pathologist to be able to help a clinician arrive at a definitive diagnosis of LICHEN PLANUS, relevant clinical information regarding the patient’s use of prescription drugs, flavored oral hygiene/food products, and/or the presence of large restorations must be included on the Incyte Diagnostics’ biopsy requisition form at the time of specimen submission. If scant, or no clinical information is provided, the most likely pathologic diagnosis that will appear on the finalized biopsy report is CHRONIC LICHENOID MUCOSITIS. If, or when, that happens, it is then necessary to perform a clinico-pathologic correlation in order to exclude possible drug, chemical and/or contact reactions. Only then can a final diagnosis of oral lichen planus be made.

The bottom line: The diagnosis of oral lichen planus is based on a correlation of both clinical and microscopic evidence. One without the other isn’t enough anymore. For additional information on lichen planus and related lesions, or for any question pertaining to oral pathology consultative ser vices, feel free to call Dr. Achterberg at (509) 892-2732. (This post was a reprint of a 2007 article by Dr. Achterberg).

OralLichenPlanus

References:
1. Neville, B.W., Damm, D.D., Allen, C.M., and Bouquot, J.E., in Oral & Maxillofacial Pathology, 2nd ed. Philadelphia: W.B. Saunders, 2002:300-307, 680- 685.
2. Shklar, G., and McCarthy, P.L.: The oral lesions of lichen planus, Oral Surg 14:164, 1961.
3. Greenberg, M.S. and Glick, M., in Burket’s Oral th Medicine, 10 ed. Hamilton, Ontario Canada: B.C. Decker 2003:110-112.

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