Discoloration in the Hands.

A 42-year-old woman had pain in her hands and discoloration on the tips of her fingers and toes when exposed to cold (Figure 1). She had chronic systemic lupus erythematosus that was diagnosed seven years earlier. Her urinalysis findings were abnormal, including the presence of proteinuria and hematuria. Her creatinine level was normal, and her antinuclear antibody titer was 1:2,560. Renal biopsy, which was performed because of the proteinuria, revealed stage V membranous lupus nephritis. Question Based on the patient’s history and physical examination findings, which one of the following is the most likely diagnosis?