Exploring the connection between hidradenitis suppurativa and erythema nodosum: a case report.

Erythema nodosum (EN) is inflammation of subcutaneous fat. Etiologies include autoimmune diseases, drugs, infections, pregnancy, malignancy, and idiopathic origins. A 37-year-old female with a history of recurrent cellulitis and type II diabetes presented with worsening swollen lumps on upper extremities for four months during a Hurley Stage III hidradenitis suppurativa (HS) flare. Exam revealed multiple erythematous pustules and warm indurated nodules over diffuse edema on the upper extremities. Lesions were refractory to trimethoprim/sulfamethoxazole, cefalexin, clindamycin, and levofloxacin. Routine blood labs, ESR, and ANA were unremarkable. EN was diagnosed. Trimethoprim/sulfamethoxazole, saturated solution potassium iodide (SSKI), and ibuprofen were prescribed. At the three-week follow-up, EN completely resolved the issue except for one lesion. Literature review revealed one case of EN manifestation in association with HS but was complicated by Beçhet's syndrome. We propose HS as an underlying cause of EN and SSKI an effective treatment for EN and HS.