A Case of Plasma Donation Affecting Treatment of Pemphigus Foliaceous

Summary: A 62-year-old female with a past medical history of long-standing dermatitis on the face presented to the dermatology clinic to restart Plaquenil. Previously, connective tissue disease was on the differential due to a positive response to Plaquenil. Prior to this visit, for the past two years, the patient had been on and off Plaquenil. Her dermatitis had recently worsened and spreads quickly. Topical steroids were not helpful. A previous biopsy in 2014 showed a negative ELISA. She was unresponsive to Plaquenil and was started on a prednisone taper. A repeat biopsy was done and methotrexate was introduced. She an exacerbated rash on the right side of the face since she completed the prednisone taper. At a subsequent visit, the patient was doing better and methotrexate was increased to 15mg weekly. Given the complex nature of the rash, images of the rash with patient consent were shared with international attendings for a second opinion. A month after this visit on 7 weeks of methotrexate (dose increased from 10mg to 15mg daily), the patient’s labs came back as positive for desmoglein antibodies which were consistent with pemphigus foliaceous. At this visit, the patient was advised to continue methotrexate 15mg weekly and folic acid 1mg daily. At 32 weeks of methotrexate initiation, the dosage was increased to 17.5mg due to a minor flare. At 47 weeks, it was continuing to flare and the dose was increased to 20mg. At 52 weeks on methotrexate, flares continued. The patient was noted to be donating plasma 2 times a week for the past two months. She was advised to discontinue donating plasma for 8-12 weeks. At 64 weeks of methotrexate and since about 90 days after discontinuation of plasma donation, symptoms on methotrexate were significantly better. Ultimately, the patient was advised to continue to avoid donating plasma as symptoms improved.