A 38 year old woman presented with a 2 week history of tender, swollen nodules on her lower legs. Her only current medication was a triphasic oral contraceptive. She denies any history of inflammatory bowel disease, sarcoidosis, or chronic infections. Physical examination revealed erythematous nodular swellings on the anterior lower legs. A punch biopsy specimen was obtained from a lesion on the left anterior tibia reveals a septal inflammation of subcutaneous fat. This best description of this rash is: