Interstitial granulomatous dermatitis in a patient with lupus erythematosus.

To the Editors: Interstitial granulomatous dermatitis (IGD) is an uncommon idiopathic dermatosis recently described by Ackerman et al. This entity is characterized by the combination of a variable clinical presentation and a peculiar histopathologic pattern. IGD is in some cases associated with autoimmune or connective tissue disorders such as rheumatoid arthritis, systemic lupus erythematosus, systemic vasculitis, and lymphoproliferative disorders. When the condition is associated with nonrheumatoid arthritis, it is known as Ackerman syndrome. We evaluated a 44-year-old woman with a 1-month history of polyarthritis and skin lesions on limbs. She was diagnosed with systemic lupus (based on cutaneous, immunological, hematological, and cardiac features) when she was 24 years old. She presented with erythematosus to violaceous plaques with annular configuration on her limbs (Figs. 1A, B). The lesions were bilateral and symmetrically distributed, and they were not pruriginous or painful. Furthermore, she had polyarthralgias, and physical examination showed a nondeforming arthritis involving the ankles and the knee joints. Skin biopsy obtained from one lesion showed an infiltration of the reticular dermis with a predominance of interstitial and palisaded histiocytes with a few areas of degenerating collagen bundles associated with a variable number of polymorphonuclear neutrophils and eosinophils (Fig. 2A). There was no sign of vasculitis. The infiltrate stained strongly with anti-CD68 antibodies (Fig. 2B). The findings were consistent with IGD. Oral corticosteroids were administered, and the skin lesions and the arthritis resolved completely within 18 weeks. Clinical follow-up at 1 year did not show any recurrence. IGD is a condition that usually affects middle-aged patients with a female predominance. The dermatosis is probably underrecognized because of its variable cutaneous expression, including papules, plaques, nodules, and subcutaneous linear cords. Histology reveals a diffuse inflammatory infiltrate composed of histiocytes distributed either interstitially between collagen bundles or as palisaded granulomas around areas of collagen necrosis throughout the dermis.