To the Editor:
Interstitial granulomatous dermatitis (IGD) is an uncommon idiopathic dermatosis recently described by Ackerman et al.1 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.2 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.3
Sometimes, dermal mucinosis may be seen. Frequently, structures resembling miniature “Churg–Strauss” granulomas can be observed.
The disease must be differentiated both clinically and histopathologically from erythematous or patch granuloma annulare4 (Table 1). Joint involvement may appear before, during, or after the onset of the cutaneous manifestations. The arthritis is usually symmetrical and mainly affects the small joints.
Some authors suggest that deposition of an immune complex mediates the pathogenesis of IGD and consider it as a form of the group of disorder called “palisaded neutrophilic and granulomatous dermatitis of immune complex disease.” Chu et al5 found features of vasculitis in the early lesions and palisaded histiocytic granulomas during the second stage. This fact may support the hypothesis that IGD is a subset of vasculitis, despite the absence of authentic vasculitis when the symptoms are present.
In conclusion, histopathologic findings along with clinical correlation may enable a correct diagnosis of IGD. This entity should be suspected in patients who have either rheumatoid symptoms or underlying autoimmune disorders and whose histopathologic findings are similar to either palisaded or interstitial granuloma annulare.
Ana García-Rabasco, MD
Altea Esteve-Martínez, MD
Violeta Zaragoza-Ninet, MD
Jose-Luís Sánchez-Carazo, PhD
Víctor Alegre-de-Miquel, PhD
Departments of Dermatology, Valencia General University Hospital and Medical School, Spain
1. Ackerman AB, Guo Y, Vitale PA, et al. Clues to diagnosis in dermatopathology. Vol 3. Chicago, IL: ASCP Press; 1993:309–312.
2. Tomasini C, Pippione M. Interstitial granulomatous dermatitis with plaques. J Am Acad Dermatol
3. Bañuls J, Betlloch I, Botella R, et al. Interstitial granulomatous dermatitis with plaques and arthritis. Eur J Dermatol
4. Blaise S, Salameire D, Carpentier PH. Interstitial granulomatous dermatitis: a misdiagnosed cutaneous form of lupus erythematosus? Clin Exp Dermatol
5. Chu P, Connolly MK, LeBoit PE. The histopathologic spectrum of palisaded neutrophilic and granulomatous dermatitis in patients with collagen vascular disease. Arch Dermatol