Erythema nodosum presenting as a breast mass in pregnancy

Abstract

A 34-year-old female at 17 weeks gestation presented to the emergency room complaining of a painful, raised left breast mass that had been enlarging over the past couple of weeks. The patient reported fevers and chills. On examination, there was a 7 cm firm, immobile, tender mass at the 12 o'clock position of the left breast. The skin overlying the breast mass was red and warm, with small areas of excoriation ( Figure 1). Laboratory findings demonstrated a white blood cell count of 14 × 10 3 /µL (normal range 4.5-11 × 10 3 /µL) and sedimentation rate of >136 mm/h (normal range 0-20 mm/h). An ultrasound of the left breast and axilla demonstrated multiple enlarged left axillary lymph nodes and edema with skin thickening in the left breast at the site of palpable concern, without a focal mass ( Figure 2). An ultrasound-guided core needle biopsy of a left axillary lymph node revealed no malignant cells.Subsequently, the patient noticed redness of the upper inner left breast and developed a new erythematous rash with similar rash in the bilateral legs and upper extremities. A repeat ultrasound of the left breast was performed, again demonstrating nonspecific edema.An ultrasound-guided core biopsy was performed of the left breast and showed acute and chronic inflammation (Figure 3). Tissue culture was positive for Corynebacterium. A skin punch biopsy of the left tibia demonstrated septal panniculitis, consistent with erythema nodosum (Figure 4). The patient began oral prednisone and oral antibiotics for 7 days, with significant improvement in her symptoms. Erythema nodosum (EN) is characterized by the rapid onset of tender, erythematous subcutaneous nodules most commonly localized to the pretibial lower extremities, but can involve the trunk and upper extremities. EN is likely due to a hypersensitivity reaction in F I G U R E 1 Erythematous raised, excoriated rash involving the left breast [Color figure can be viewed at wileyonlinelibrary.com] F I G U R E 2 Targeted ultrasound of the left breast shows skin thickening (white arrow) and diffuse hypoechogenicity of the subcutaneous tissue (red arrow) [Color figure can be viewed at wileyonlinelibrary.com]