A pitfall in dermatopathology

A 47-year-old man with 3 years history of a pruritic plaque, 1×3 cm on his left leg attended a dermatology clinic. An incisional biopsy was done with the differential diagnoses of: 1) Hypertrophic lichen planus, 2) Lichen simplex chronicus, 3) Psoriasis, 4) Bowen's disease. A diagnosis of “Fibroepithelioma” was suggested by histopathologist who was not compatible with clinical diagnosis. Careful review of slide showed that the specimen had been cut horizontally in the laboratory, which had misled the pathologist. By vertical sectioning the block and doing another biopsy, the diagnosis of hypertrophic lichen planus was confirmed. The patient was treated with intralesional triamcinolone injection and 4 weeks later the lesion was completely healed with residual hyperpigmentation.