Dermoscopic Polymorphism of a Pigmented Eccrine Poroma on the Leg: A Diagnostic Pitfall.

Pigmented eccrine poroma (PEP) is a rare benign adnexal tumor that can closely mimic melanoma clinically and dermoscopically, particularly when it occurs on non-acral locations. We report the case of a 31-year-old man who presented with a slow-growing, well-circumscribed brown nodule on his left leg that had been evolving for four years. Dermoscopy revealed a polymorphic pattern with chalice-form vessels, perivascular white halos, a frog's egg appearance, and structureless blue and white areas suggestive of melanoma. Histopathological examination confirmed the diagnosis of pigmented eccrine poroma. Complete surgical excision was performed with no recurrence at two-year follow-up. This case highlights the importance of recognizing the characteristic dermoscopic features of PEP to avoid unnecessary aggressive procedures and patient anxiety.