Palisaded neutrophilic and granulomatous dermatosis

A 22-year-old woman with mixed connective-tissue disease presented with a 5-month history of recurrent episodes of tender, erythematous papules, nodules, and edematous plaques on the upper extremities and thighs. Cutaneous lesions occurred in the setting of livedo reticularis. A biopsy specimen showed interstitial and perivascular inflammation with lymphocytes, macrophages, neutrophils, nuclear dust, collagen alteration, extravasated erythrocytes, and fibrin within small superficial blood vessels. These changes were consistent with a diagnosis of palisaded neutrophilic and granulomatous dermatosis, which is a rare entity that includes a combination of a neutrophilic infiltrate, abnormal or altered collagen, granuloma formation, and leukocytoclastic debris in the context of an immune-mediated collagen vascular or systemic disease. The underlying mechanism remains poorly understood. Treatment is limited, and resolution of lesions typically occurs within several months to years.