Cutaneous Involvement in Catastrophic Antiphospholipid Syndrome in a Multicenter Cohort of 65 Patients.

Importance: Catastrophic antiphospholipid syndrome (CAPS) is a severe, rare complication of antiphospholipid syndrome (APS), but cutaneous involvement has not yet been adequately described. Objective: To describe cutaneous involvement during CAPS, its clinical and pathological features, and outcomes. Design, Setting, and Participants: This cohort study was a retrospective analysis of patients included in the French multicenter APS/systemic lupus erythematosus register (ClinicalTrials.gov: NCT02782039) by December 2020. All patients meeting the revised international classification criteria for CAPS were included, and patients with cutaneous manifestations were analyzed more specifically. Main Outcomes and Measures: Clinical and pathological data as well as course and outcome in patients with cutaneous involvement during CAPS were collected and compared with those in the register without cutaneous involvement. Results: Among 120 patients with at least 1 CAPS episode, the 65 (54%) with skin involvement (43 [66%] women; median [range] age, 31 [12-69] years) were analyzed. Catastrophic antiphospholipid syndrome was the first APS manifestation for 21 of 60 (35%) patients with available data. The main lesions were recent-onset or newly worsened livedo racemosa (n = 29, 45%), necrotic and/or ulcerated lesions (n = 27, 42%), subungual splinter hemorrhages (n = 19, 29%), apparent distal inflammatory edema (reddened and warm hands, feet, or face) (n = 15, 23%), and/or vascular purpura (n = 9, 14%). Sixteen biopsies performed during CAPS episodes were reviewed and showed microthrombi of dermal capillaries in 15 patients (94%). These lesions healed without sequelae in slightly more than 90% (58 of 64) of patients. Patients with cutaneous involvement showed a trend toward more frequent histologically proven CAPS (37% vs 24%, P = .16) than those without such involvement, while mortality did not differ significantly between the groups (respectively, 5% vs 9%, P = .47). Conclusions and Relevance: In this cohort study, half the patients with CAPS showed cutaneous involvement, with a wide spectrum of clinical presentations, including distal inflammatory edema. Skin biopsies confirmed the diagnosis in all but 1 biopsied patient.