What happened, in summary

A 56-year-old woman was being treated for pemphigus vulgaris when she was diagnosed with a new infiltrating ductal breast cancer. Before the cancer diagnosis, her autoimmune disease had required prednisone, usually 12.5–25 mg daily, and azathioprine 50–100 mg daily, with only partial control.

For the breast cancer, she underwent excision surgery with axillary lymph-node biopsy and then radiotherapy. Tamoxifen 20 mg daily was started together with a gonadotropin-releasing hormone analogue. While she was receiving cancer treatment, her pemphigus worsened. Because of the malignancy, her previous immunosuppressive therapy was suspended, and the care team chose a separate home-based immunoglobulin approach for the autoimmune disease. Over 18 months, the pemphigus improved substantially and her steroid dose could be reduced.

Her breast-cancer endocrine treatment continued while the autoimmune disease was managed with a separate treatment approach.