Well-Differentiated Squamous Cell Carcinoma Arising in Chronic Hypertrophic Lichen Planus: A Case Report.

Squamous cell carcinoma (SCC) arising in chronic hypertrophic lichen planus represents a rare but clinically relevant malignant transformation, presenting diagnostic complexities attributed to morphological similarities with other dermatoses. The paucity of documented cases necessitates comprehensive documentation of clinical and histopathological findings. A 56-year-old woman presented with a six-year history of a progressively enlarging, pruritic, hyperpigmented plaque localized to the right lower limb. Clinical examination revealed a well-defined, indurated plaque measuring 5×3 centimeters with areas of central erosion over the lateral aspect of the right calf. Histopathological analysis of a punch biopsy specimen demonstrated well-differentiated SCC characterized by epidermal cells in nests showing keratinization and formation of keratin pearls, with evidence of dermal invasion. The differential diagnostic considerations included hypertrophic lichen planus, chromoblastomycosis, and SCC. This case emphasizes the need for vigilance in chronic hypertrophic lichen planus to detect malignant transformation.