2 Case Reports in Medicine (a) (b) (c) Figure 1: Skin lesions: case 1 on the right side and case 2 on the left side. parts of both legs of one-week duration; no pitting edema was present. The signs had gradually developed on the lower one-third of the right leg in an area 3–5 cm in diameter and on the left leg in an area 4-5 cm in diameter. In the physical examination, the patient was ill without fever and erythema, and nodular lesions were seen (Figure 1(b)). 2.2. Case Two. A married 22-year-old lady presented with a chief complaint of pain and tenderness on the anterior part of her right leg, which gradually increased in intensity; the same problems appeared on the left leg, too. Physical examination revealed 0.5 × 0.5 cm nodules with 3–50 cm erythematous margins. She was ill but afebrile (Figure 1(c)). Both the patients reported sore throat, fever, chills, and general symptoms of a cold two weeks previously and reported taking oral contraceptives. Physical examination did not yield any abnormal ﬁndings. After 8 weeks, the conditions completely resolved. During the sickness period the patients received a single dose of penicillin 1200000 U intramuscularly and nonsteroidal anti-inﬂammatory drugs. After 8 weeks the conditions completely resolved. 3. Laboratory Findings Table 1 presents the laboratory data of the two cases. 4. Discussion The eruptive phase of erythema nodosum starts with ﬂulike symptoms of fever and generalized aches and pains. Arthralgia might occur and appear before or during the eruptive phase. Most lesions in infection-induced erythema nodosum ameliorate within 7 weeks, but active disease may last up to 18 weeks. In contrast, 30% of idiopathic erythema nodosum cases may last more than 6 months. Febrile illness with dermatologic ﬁndings includes abrupt onset of illness with initial fever, followed by a painful rash within 1-2 days [4]. When erythema nodosum is diagnosed, it is important to ﬁnd out the underlying conditions. These include a detailed history, including drug and past medical history, a careful physical examination, laboratory investigation, and a chest X-ray. EN is classiﬁed as idiopathic or secondary to other diseases [5]. Some causes of erythema nodosum and its diﬀerential diagnosis are listed in Table 1. There are various etiologic factors for erythema nodosum based on the disease pattern of the region. Table 2 presents some retrospective studies that show this variation based on geographical diﬀerences [3, 6–9]. The relationship between a previous episode of upper respiratory tract infection by group A beta-hemolytic strep- tococci and erythema nodosum is fully known, particularly in children and young adults. Usually, the cutaneous lesions appear 2-3 weeks after throat infection, and they are associated with an increase in antistreptolysin O (ASO) titer. An intradermal positive test to streptococcal antigens is often found in patients with erythema nodosum secondary to streptococcal infections, although when the cutaneous nodules develop, the cultures of ordinary throat swabs usually do not detect microorganisms [1, 10].