[Differential diagnoses: skin changes on the leg and their significance]

Cutaneous lesions of the lower extremities represent a frequent diagnostic challenge in daily clinical practice, as a wide range of infectious, inflammatory, vascular, neoplastic, and metabolic disorders may present with similar clinical features. Hypodermitis as a manifestation of chronic venous insufficiency, for example, is often misdiagnosed as erysipelas, which may result in delayed or inadequate treatment and potentially irreversible fibrotic changes. This article addresses this issue by presenting an illustrative case and provides a structured overview of relevant differential diagnoses of skin lesions affecting the lower legs. In addition to acute and chronic infectious dermatoses, inflammatory and immune-mediated diseases, vascular-related skin changes, neoplastic entities, and metabolically associated dermatoses are discussed. The aim is to facilitate early and targeted diagnostic evaluation by comparing clinical and anamnestic features. Accurate classification is essential, as treatment strategies, prognosis, and disease course vary considerably among these conditions. This article is intended to help avoid misdiagnosis and initiate early, etiologically based treatment.