Lichenoid keratosis is frequently misdiagnosed as basal cell carcinoma.

Lichenoid keratosis (LK), also known as benign lichenoid keratosis or lichen planus-like keratosis, is a solitary, pink to red-brown scaly plaque representing a host immunological response to a variety of precursor lesions. LK is often misdiagnosed as a dermatological malignancy owing to its clinical resemblance to basal cell carcinoma (BCC) or Bowen disease. We performed a retrospective analysis of the pathology records of a series of LK lesions with reference to the demographic features and accuracy of clinical diagnosis. The pathology records from 2008 to 2009 of 263 consecutive patients with a histological diagnosis of LK from a specialized skin laboratory were retrieved. Data relating to clinical diagnosis, age, sex, anatomical location, time of year of presentation and any coexistent pathological lesions adjacent to the LK were recorded. Mean age at presentation was 64 years (range 34-96), and 58% of patients were female. The most common anatomical site was the chest/anterior torso, followed by the back and legs. The most common coexisting lesion was solar keratosis at 14%, followed by seborrhoeic keratosis (SK) at 7.8%. The correct clinical diagnosis of LK was made in 29.5% of cases. The most common clinical diagnosis was BCC (47%), while SK was the preferred diagnosis in 18%. A clinical diagnosis was not given in 5.5% of cases. In conclusion, it appears that LK is frequently misdiagnosed, with misdiagnosis occurring in > 70% of cases in this study.