Lichen planus‐like keratosis: clinicopathological evaluation of 1366 cases

Lichen planus-like keratosis (LPLK) is a frequent skin lesion usually biopsied to rule out basal cell carcinoma (BCC). Because of overlapping histopathological characteristics, LPLK is frequently muddled with lichen planus (LP), lichenoid actinic keratosis (LAK), and lupus erythematosus (LE).To investigate the clinical and histopathological characteristics of LPLK.A clinicopathologic review was performed of all LPLK cases (1366) signed in one calendar year in a busy academic practice.LPLK occurs mostly as a single lesion (97%) with the chest (41.4%) being the most common site. It is almost equally present in women and men (51.5%-48.5%). The most common clinical concern (65%) is basal cell carcinoma. Parakeratosis, red blood extravasation, and presence of dermal eosinophils and plasma cells, usually not seen in lichen planus, are helpful signs to suggest LPLK but are seen only in a minority of cases.Clinicopathologic correlation is necessary to diagnose lichen planus-like keratosis, as the most consistent feature is a clinical history of a lesion/neoplastic process rather than an inflammatory process. There are histopathologic features that can help distinguish lichen planus-like keratosis from lichen planus; however, these features are nonspecific and lacking in almost half of the cases.