Benign Lichenoid Keratosis of the Breast: Clinicopathologic Correlation of a Rare Presentation

Benign lichenoid keratosis (BLK), also known as lichen planus-like keratosis, is a regressive inflammatory lesion that often mimics melanocytic or inflammatory dermatoses. It typically arises in middle-aged to elderly individuals, most commonly on sun-exposed skin, and histologically represents a lichenoid inflammatory response within a pre-existing epidermal lesion such as solar lentigo or seborrheic keratosis. In the present paper, we report a rare case of BLK occurring on the breast of a 53-year-old woman who presented with a solitary, asymptomatic pigmented lesion on the right breast. Clinical examination revealed a well-defined, flat brown macule measuring approximately 0.5 cm, with no surface changes or regional lymphadenopathy. Histopathological examination revealed compact hyperkeratosis, basal vacuolar degeneration, a dense band-like lymphocytic infiltrate, apoptotic keratinocytes, and pigment incontinence with numerous dermal melanophages, features characteristic of BLK. The patient's lesion was completely excised with no recurrence at follow-up. This case highlights the diagnostic challenge of BLK at atypical, non-sun-exposed sites and underscores the importance of clinicopathologic correlation and histopathologic confirmation to prevent misdiagnosis and unnecessary treatment.