Research Article Granulomatous Dermatitis and Systemic Disease: An Association to Consider Alberto Corrà , 1 Lavinia Quintarelli , 1 Alice Verdelli , 2 Francesca Portelli , 3 Daniela Massi , 3 and Marzia Caproni 1 1 Dermatology Unit, Department of Health Sciences, University of Florence, Florence, Italy 2 Department of Experimental and Clinical Biomedical Sciences “Mario Serio”, University of Florence, Viale Morgagni 50, 50134 Florence, Italy 3 Division of Pathological Anatomy, Department of Surgical and Translational Medicine, University of Florence, Florence, Italy Correspondence should be addressed to Alberto Corrà; alberto.corra@unifi.it Received 28 January 2020; Revised 11 July 2020; Accepted 27 July 2020; Published 30 September 2020 Academic Editor: Paolo Spagnolo Copyright © 2020 Alberto Corrà et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Granuloma annulare (GA) and interstitial granulomatous dermatitis (IGD) are granulomatous dermatoses with variable clinical appearances. GA is associated with diabetes mellitus, metabolic syndrome, chronic infections, and malignancies, while two Japanese reports described unusual cases of interstitial-type GA in setting of Sjogren syndrome. IGD was associated with rheumatoid arthritis, systemic lupus erythematosus, and autoantibodies. We report a case series of six patients with GA or IGD. Half of the patients were diagnosed with Sjogren syndrome, while all of them presented ANA positivity and the majority reported arthralgia. In many cases, GA showed interstitial-type histology, arising challenges in differential diagnosis with IGD. The overlap of clinical and histological features of GA and IGD can be explained considering them as a broad disease spectrum, including also the other forms of reactive granulomatous dermatitis. These conditions should be considered as an indicator of possible systemic disorders or other immunological dyscrasias, for which patients must be screened. Sjogren syndrome may be associated to GA also in Caucasians. 1. Introduction Granulomatous dermatoses are a group of clinically and histologically heterogeneous inflammatory skin conditions including granuloma annulare (GA) and reactive granulo- matous dermatitis (RGD). GA was described in association with diabetes mellitus, chronic infections, malignancies, and thyroid autoimmune diseases [1], while in the last decade association with autoim- mune systemic diseases was reported in Japanese population. Among these, two GA cases in association with Sjogren syndrome are as follows: one with dermatomyositis and four in the setting of systemic sclerosis or morphoea [2–8]. Clinically, GA erupts usually with ring-like erythematous plaques, scattered coalescing papules, or nodules. While the localized GA classically appears on the hands and feet, the generalized form involves extremities and trunk, and the subcutaneous form usually involves the lower extremities in children. Perforating, patched, macular, pustular, and palmoplantar are rare variants. On histology, mucin with a palisading or interstitial configuration of granulomatous inflammation represents the typical finding [6]. The palisading pattern appears as dermal palisading histiocytes and lymphocytes surrounding a central zone of necrobiotic collagen in upper and middle dermis. In opposition, the interstitial pattern consists of histiocytes scattered around collagen bundles and blood vessels [9]. Under the term RGD, in 2015, Rosenbach et al. unified several granulomatous inflammatory skin reactions with similar clinical and histological features, including palisaded Hindawi BioMed Research International Volume 2020, Article ID 3281380, 6 pages https://doi.org/10.1155/2020/3281380