Background The diagnosis of oral lichenoid lesions (OLL) remains a challenge for clinicians and pathologists. Although, in many cases, OLL cannot be clinically and histopathologically distinguishable from oral lichen planus (OLP), one important difference between these lesions is that OLL has an identifiable etiological factor, e.g. medication, restorative material, and food allergy. The list of drugs that can cause OLL is extensive and includes anti-inflammatory drugs, anticonvulsants, antihypertensives, antivirals, antibiotics, chemotherapeutics, among others. This work aimed to perform a literature review of OLL related to chemotherapy drugs and to report two cases of possible OLL in patients with B-cell and T-cell non-Hodgkin lymphomas in use of chemotherapy and adjuvant medications. We also discuss the challenge to clinically and histopathologically differentiate OLL and OLP. Case presentation In both cases, oral lesions presented reticular, atrophic, erosive/ulcerated, and plaque patterns. The diagnosis of OLL was initially established in both cases by the association of histopathology and history of onset of lesions after the use of medications. Although the patients have presented a significant improvement in the oral clinical picture for more than 2 years of follow-up, they still have some lesions. Conclusion A well-detailed anamnesis associated with the drug history, temporal relationship of the appearance of the lesions, and follow-up of patients are fundamental for the diagnosis of OLL related to drugs. Nevertheless, its differentiation from OLP is still a challenge.

Considering a few epidemiologic studies which describes clinic and pathologic features and prevalence of oral lichen planus (OLP) in Brazil as well as the importance of such studies in order of health care services plans and to verify changes along the years, the present study aimed to evaluate the sociodemographic and clinical profile of 49 participants diagnosed with OLP during a period of ten years. For the sample selection, the clinical and histopathological criteria for the diagnosis of OLP proposed by the American Academy of Oral and Maxillofacial Pathology were used, except for the criterion “absence of epithelial dysplasia”. Most individuals were female (75.5%; p = 0.0005). White individuals were significantly older than the black individuals (67.7 vs 49.2 years; p = 0.001). Lesions affecting multiple bilateral/symmetric sites were more common than lesions in a single bilateral/symmetric site (77.6%; p = 0.0001). The most commonly affected sites were buccal mucosa (85.7%), tongue (65.3%), gingiva (42.9%), and lips (32.7%). Most lesions were white (reticular pattern was found in 93.9% and plaque in 75.5% of cases). Plaque pattern was more common in older individuals (p = 0.006). During the different moments of evaluations some individuals did not meet the American Academy of Oral and Maxillofacial Pathology criteria due to the absence of oral lesions with multifocal symmetric distribution. Therefore, in a first consultation, if the patient does not present multifocal symmetric distributed lesions, the diagnosis of OLP cannot be excluded and the patient should be followed-up.