Relationship between cutaneous polyarteritis nodosa (cPAN) and macular lymphocytic arteritis (MLA): Blinded histologic assessment of 35 cPAN cases

Background Cutaneous polyarteritis nodosa(cPAN) is a skin medium vessel neutrophilic arteritiswith livedo, nodules, and ulcerations. Macular lymphocytic arteritis(MLA) is a small arteritiswith erythematous or pigmented macules and typical histologic features (a lymphocytic infiltrate, concentric fibrin ring, no disruption of the internal elastic lamina). Objective We sought to assess the frequency of clinical and histologic features of MLA in patients with cPAN. Methods This was a monocentric retrospective analysis of patients given the diagnosis of cPAN with blinded assessment of skin biopsyspecimens. Results All 35 patients included had an infiltrated livedo, nodules, or both. Ulceration was rare. Erythematous or pigmented lesions were present in 54% of patients. Predominantly lymphocytic arteritis, a paucity of neutrophils, concentric fibrin ring, and absence of internal lamina elastic disruption were present in 60%, 20%, 18%, and 23% of patients, respectively. Median follow-up was 11 years. None of the patients had systemic involvement, and 57% had a complete remission. The incidence of complete remission was not different between patients having a predominant lymphocyte infiltrateor few neutrophils. Limitations This was a retrospective, monocentric study without a control group of patients with MLA. Conclusions Our data do not favor the classification of cPAN and MLA as distinct entities.