RESUMEN
BACKGROUND/OBJECTIVES: Lymphocytic hidradenitis is a non-specific histopathological feature observed in many dermatoses such as lupus erythematosus, morphea or scleroderma. When it occurs it is usually accompanied by the other distinctive histological features of those conditions. Isolated lymphocytic hidradenitis is uncommon and its clinical features and associated underlying medical conditions are still undetermined. METHODS: We performed a retrospective review of patients who clinically presented with annular erythema between 2000 and 2016. Altogether, 30 patients with a histopathological presentation of isolated lymphocytic hidradenitis were identified. Their following characteristics were recorded: clinical features, number and localisation of lesions, serology and other associated medical conditions. RESULTS: Isolated lymphocytic hidradenitis was found most frequently in middle-aged women. Most patients (n = 28, 93%) presented with many annular erythematous patches and plaques with mild pruritus; 22 (73%) had the SS-A antibody and 17 (57%) met the diagnostic criteria of Sjögren syndrome. Among these patients, 11 had primary and six had secondary Sjögren syndrome associated with systemic lupus erythematosus. Altogether 15 (50%) patients tested positive for a high titre of the antinuclear autoantibody. Other underlying diseases identified during the follow-up period include cryoglobulinaemia, angioimmunoblastic T-cell lymphoma, autoimmune hepatitis, hepatitis C infection and toxic thyroid goitre. CONCLUSIONS: Lymphocytic hidradenitis is a microscopic finding associated with annular erythemas of Sjögren syndrome. Systemic survey for sicca symptoms and work up for autoimmune diseases, including antinuclear antibodies, SS-A, SS-B antibodies, cryoglobulin, lymphoma, viral and autoimmune hepatitis should be performed to facilitate the correct diagnosis.