First off, good for you, NOT that all this is happening, but that your SCLE rash was dx'ed quickly, nailing your dx down fast. I was also positive for anti-Ro, and here are some things I was told.
1. People with either of the SCLE rashes (annular or psoriasiform) tend to be extremely photosensitive, so sun precautions are essential. (I wear hats, long-sleeves & long trousers, and sunblock; and I avoid prolonged exposure to midday sun.) I asked if the sensitivity would abate & was basically told NO, bad news for outdoor lovers.. but then one weighs the potential for organ damage, and it's a no-brainer.
2. People with lupus are indeed "eligible" for multiple rash types. I got a huge discoid (scarring) lesion on my face & needed surgical repair b/c it wouldn't heal over. BTW, discoid lesions on the scalp can cause permanent hair loss, which you do not want.
3. Hats should be of dense material & have broad brims. Outdoor provisioners often sell ones that are UV-sun-block rated. I've seen Australian brands advertised that look well-made.
4. The more widespread the rash (ex: both above & below shoulders), the more likely the patient will have add'l systemic issues.
5. Studies have been mixed in how people in the anti-Ro subset tend to fare, when compared to the other subgroups. One study showed less frequent major organ involvement (heart, lungs, kidney, brain), but another showed no appreciable difference. So I was told to assume I'd do well but to behave as though I wouldn't, i.e., take my meds, avoid sun, get flu (etc.) shots, and follow-up regularly with rheumatologist (regular blood labs & urinalysis).
6. I use a block with SPF 32+ on my face, but being a woman, I can then slather on a foundation that also has SPF. (My husband says I trowel it on in the morning & chisel it off at night.
) One's face & ears tend to grab sun, so I take special care of those. Also, watch your driving or passenger arm, the one adjacent to your car window.
I think C3 and C4 are "serum complements", which act as helpers in immune system function; and that disease processes (inflammation, autoantibodies, etc.) can deplete these essential components. In lupus, the immune system is both over-active and aberrant. Steroids SUPPRESS the immune system. Plaquenil is milder, and it only modifies but doesn't outright suppress; and, worse, it can take 4-6 months to reach its full effect. So rather than waiting, maybe your dr. wants your C3 & C4 to resolve more quickly, and believes that Prednisone is the best way to achieve that? I'd just ask him---and also if there's any other reason C3 & C4 deplete.
I hope others who know more about C3 and C4 chip in.
Glad you found us. Let us know what happens next. All my best, Vee