This includes pemphigus vulgaris, bullous pemphigoid, mucous membrane pemphigoid (aka ocular cicatricial pemphigoid), pemphigus foliaceus, pemphigus vegetans, IgA pemphigus, paraneoplastic pemphigus, or gestational pemphigoid.
All P/P rare autoimmune diseases are skin-blistering conditions. Steroid medication is often recommended in conjunction with immunosuppressant therapy in order to lower steroid dosages and bring the patient to remission (or at the very least, on a low-dosage maintenance program).
Since this is a condition that affects the skin, any invasive surgery will require an adjustment to medications prior to and after the procedure. This includes dental work (i.e. tooth extraction). Definitely for knee replacements, hip replacements, and any other invasive procedure.
Therefore, it is very important to advise your primary care physician, dentist, internist, rheumatologist, ob-gyn, and any other medical professional you are seeing on a regular basis. Each doctor needs to know about your new diagnosis and the medications you are taking, including any adjustments throughout your treatments, so they can keep track as well.
Your entire medical team is working together to keep you healthy, and keeping all of them in the loop is to your advantage.