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 arteritis with livedo, nodules, and ulcerations. Macular lymphocytic arteritis (MLA) is a small arteritis with 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 biopsy specimens. 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 infiltrate or 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.