Panniculitis: a diagnostic algorithm

Panniculitis is broadly defined as inflammation of the subcutaneous tissue. Although a number of diseases involve the panniculus, the spectrum of morphological patterns is limited, namely lobular and septal. Therefore, despite the perceived complexity of this topic, careful analysis of the pattern and the inflammatory infiltrate allows a histological diagnosis in a majority of cases. In this review we will cover the most important types of panniculitis, and will offer a diagnostic algorithm to help analyse this type of biopsy.