A 19-year-old Caucasian female in the United States Army with an unrevealing past medical history presented due to the sudden onset of painful nodules and bruising to her on shins that developed upon awakening two days ago. She denies recent trauma to the area. No recent upper respiratory infections. No family history of sarcoidosis, rheumatoid arthritis, or other autoimmune conditions. She described the pain as a burning sensation. She denies spread of the lesions since they first appeared. She denies a history of similar symptoms in the past. She does not take any chronic medications but does admit to taking a form of emergency contraception after unprotected sexual intercourse, approximately one week prior to their appearance. Denies any joint pains. On physical examination, vitals were stable with no evidence of fever. The patient was in no acute distress. Cardiopulmonary examination was unremarkable. Skin examination revealed ill-defined symmetric subcutaneous nodules, approximately 4–5 cm in size, with bruising on the anterior shins bilaterally (Figures 1 and 2). Examination of the ankles, knees, elbows, and fingers bilaterally showed no evidence of synovitis. Elevated Sedimentation Rate (ESR) was 37 mm/hr (normal range for women 0-29 mm/hr). Erythema nodosum (EN) was highest on the differential diagnosis, and the patient was referred to Dermatology for clinical confirmation of the diagnosis. Given its appearance, Dermatology confirmed the diagnosis, and biopsy was not pursued. She was prescribed a prednisone taper of 20mg for 21 days. Upon follow up a month later, her symptoms had mostly resolved as seen in attached figures (Figures 3 and 4).

Keywords: Erythema nodosum, Emergency contraception, Panniculitis

Erythema nodosum is a form of panniculitis, more commonly seen in females, that can be associated with a wide breadth of conditions (Table 1). Oral contraceptives, as well as many other conditions, have been associated with erythema nodosum [1], [2]. EN often produces painful ill-defined symmetric subcutaneous nodules, often 1–6 cm in diameter, in areas such as the face, neck, trunk or arms but most commonly seen in the anterior surface of the lower extremities [3], [4], [5], [6]. The nodules will often regress to bruises and ultimately will disappear without bruising in 1–2 months [3]. In rare cases, the dermatologic manifestations may be associated with systemic symptoms of fevers, malaise, and joint pains [6]. EN may be a sign of an underlying medical condition such as inflammatory bowel disease, sarcoidosis, malignancy, specific bacterial infections, or from medications such as oral contracptives, sulphonamides or bromides [7]. Table 1 shows common causes of Erythema nodosum [4],[6],[7]. Despite the large differential, malignancy must always be considered as a potential cause. A paraneoplastic presentation can be seen with Non-Hodgkin’s lymphoma, Hodgkin’s lymhpma, and leukemia [6]. Diagnosis can often be made solely on patient history and physical examination. Dermatologic exam often reveals an acute onset of tender nodules on the bilateral shins. Biopsy can be considered if an atypical site is involved (ie. arms, chest) or atypical features are encountered such as ulceration or abnormally large size (>5 cm). Typically labs are not necessary unless they may assist in the diagnosis of the culprit disease (i.e. chest radiograph for sarcoidosis, ESR or C-RP for inflammatory bowel disease). Treatment is often conservative and involves raising the legs, rest, anti-inflammatories, and systemic glucocortidoids, if rapid treatment is desired. CO

Erythema nodosum is a dermatologic condition that may present with nodular erythematous eruptions that is usually limited to the extensor aspects of the extremities in patients secondary to a wide array of potential conditions as well as secondary to medications. Oral contraceptives are a known, but not commonly considered cause, of EN, and should be considered in the differential in age-appropriate females presenting in the right clinical scenario with painful nodules and bruising to the lower extremities. Treatment is often conservative, however, in severe cases, prednisone can be used.

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