Background Erythema nodosum (EN) is a type of septal panniculitis that occurs predominantly without vasculitis. EN can be caused by a wide range of etiological factors (infection, sarcoidosis, rheumatic diseases, medications, and other).
Objectives To examine the incidence and clinical features of EN in modern rheumatology practice.
Methods The study included 130 patients (19 men and 111 women, median age 39±13 years) who applied with EN as referral diagnosis to rheumatology clinic during 3-year period. Examination of patients was performed according to the developed algorithm, necessitating collection of thorough medical history, physical examination, clinical, biochemical and immunological blood tests (including CRP, ASLO, RF, anti-DNA), as well as HBs, HCV and RW/VDRL. All patients also underwent chest CT.
Results 7 (5%) patients were diagnosed with primary (idiopathic) EN (PEN), 123 - secondary EN (SEN). Association of EN with infectious process (streptococcal infection-16, mycoplasmal pneumonia-3, upper respiratory tract infection-14, yersiniosis -5 hepatitis C- 5, HIV with HCV-1, infectious mononucleosis-1) was established in 45 (35%) patients, Löfgren's syndrome was diagnosed in 45 (35%) patients, rheumatic diseases - in 20 (15%) patients (7-systemic lupus erythematosus, 5-Behcet's disease, 3-reactive arthritis, 3-primary Sjögren's syndrome, 2-rheumatoid arthritis). In 13 (10%) SEN cases other causes were found: cancer-3, allergic reactions, 3-contraception-2, endometriosis-2, vaccination-1, autoimmune thyroiditis -1, ulcerative colitis-1. In general, EN onset more often occurred during the spring-summer period (60%). PEN patients presented with small number of nodes (to 5.66±4,89), localized exclusively in the sural area. In patients with Löfgren's syndrome skin lesions typically occurred on the ankles (84%) and persisted for the shortest period of time (1,69±2,29 weeks.). In patients with rheumatic diseases EN occurred more frequently in summer time (50%), was prone to chronicity (60%), longer duration (5,51±7,58 weeks.) and wider distribution on the skin involving legs, hips, shoulders and trunk, showing tenderness to palpation while assessing pain intensity by the visual analogue scale (60±23 mm). Wrist joints and small joints of the hands and feet were significantly more often affected in this group (24% and 38%, respectively, p<0.01).
Conclusions Routine use of expanded diagnostic algorithm allowed to verify EN cause in 95% of cases, which is significantly higher as compared to other authors [1,2]. Infections and sarcoidosis were the most common causes of EN in our group of patients, which is probably related to the population characteristics of the sample. Clinical variants of EN allow to suspect the likely cause of the disease and provide a targeted diagnostic screening.
Cribier B, et al. Erythema nodosum and associated diseases. A study of 129 cases. Int J Dermatol. 1998 Sep;37(9):667-72.
Mert A, et al. Erythema nodosum: an evaluation of 100 cases. Clin Exp Rheumatol. 2007 Jul-Aug;25(4):563-70.
Disclosure of Interest None declared