Suggestions for a New Clinical Classification Approach to Panniculitis Based on a Mayo Clinic Experience of 207 Cases

Background Panniculitis, or inflammation of adipose tissue, includes a heterogeneous group of disorders with similar morphologic presentations. Currently, panniculitides are classified based on histopathologic findings only. Objective In this retrospective study of 207 cases of biopsy-proven panniculitis over 20 years at Mayo Clinic, we aimed to propose a new classification that integrates the clinical morphologic features with the histopathology of panniculitis. Methods We collected patient demographic and lesion morphologic characteristics using lesion photographs and physician notes for each of our 207 cases, including location, ulceration, scale, pattern (unilateral versus circumferential), atrophy/sclerosis (cicatricial), redness, and swelling. Results The panniculitides most likely to ulcerate were calciphylaxis (85.7% ulcerating), pancreatic panniculitis (66.6%), and α 1 -antitrypsin deficiency-associated panniculitis (100%). The panniculitides least likely to ulcerate were erythema nodosum and medication-induced and granulomatous panniculitis. This retrospective study used only descriptions in clinical notes and available medical photographs. Conclusion We present an updated classification schema of panniculitides based on clinical findings. The primary distinctions are based on ulceration, location, and number of lesions. Although complete distinction of all panniculitides based on clinical examination alone is not possible, we hope the proposed schema allows clinicians to tailor differential diagnoses.