Actinic Lichen Planus of the Forehead Mimicking Lentigo Maligna: A Case Report and Literature Review.

We describe a 52-year-old Saudi male who presented with a six-month history of an enlarging pigmented macule over the left forehead. Clinical examination revealed a 1.4 × 2 cm asymptomatic black-grey patch with irregular borders and variable pigmentation. Dermoscopy demonstrated an irregular brownish network with multifocal areas of hyperpigmentation. The differential diagnosis included lentigo maligna, junctional nevus, and actinic lichen planus. A 4-mm punch biopsy showed hyperkeratosis, mild spongiosis, melanin incontinence, and perivascular lymphocytic infiltrates, findings highly suggestive of actinic lichen planus. No evidence of malignancy was observed. This case underscores the importance of including actinic lichen planus in the differential diagnosis of pigmented facial lesions in sun-exposed areas, particularly in patients with phototype III-V skin. Histopathology remains essential for diagnostic confirmation.