How is lichen planus diagnosed?
Usually, lichen planus is relatively straightforward to diagnose. Physicians can make the diagnosis in typical cases simply by looking at the rash. If necessary, a skin biopsy may be done to help confirm the diagnosis. Under the microscope, lichen planus is distinctive in appearance. This tell-tale appearance under the microscope can be valuable in ensuring that the rash or spots are lichen planus. Persistent oral or vaginal lichen planus, with spots that thicken and grow together, can sometimes be difficult to distinguish clinically from whitish precancerous plaques called leukoplakia. A biopsy can be helpful in this situation. Widespread lichen planus with erosions in the mouth can also be confusing. A biopsy may be required to distinguish this from other conditions such as candidiasis (yeast infection), carcinoma (cancer), and ulcers in the mouth (aphthous ulcers). What causes lichen planus? In most cases, the cause of lichen planus is unknown. Some drugs, such as those containing a
