Sept 4, 2019 I was seated at a patio table outside visiting in the sunshine. For about 15 sec, my leg felt like it was on fire and got very hot, like it was burning. I shifted in my patio chair and brushed it off. I left the area and went to change clothes. I had black slacks on. When I removed my slacks, I found this! It disappeared overnight... Can anyone tell me what this is, or why it happened? I went to Urgent Care and they said it could be UV sensitivity. A second dr at full exam said it could be Livedo reticularis. A third doc at full exam ran a series of blood tests but everything looking normal. No firm diagnosis to date, looking for answers. First time this has ever happened to me and doctor said next time they will do biopsy... they believe it will return in time. Any help on this would be greatly appreciated!! No pain or symptoms other than rapid onset.
Mysterious red leg!: Sept 4, 2019 I was... - LUpus Patients Un...
Mysterious red leg!
I get the same I can’t get a answer xx
I haven’t sat in the sun since this happened... I am wondering if I were to go outside if it would likely happen again? I don’t know if there is any harm to doing this. If it did come back - then it might be good to know to confirm the theory on light sensitivity and then I could get a biopsy done.
Sorry I just picked this up I’ve had it twice under clothes mainly black I guess it heats up quicker look at my profile I put up a picture see what you think💭
Looks like there is some bluish tint under that. It could be livedo racemosa from crossing your legs. That may cut off circulation and if you had lupus/APS, I’d imagine something like this popping especially after sun/heat exposure. I get rashes from sun exposure and it doesn’t always happen in the area exposed. This is common in SLE.
Keep a log of both physical/mental health symptoms or odd things you notice that you’ve never had before. A biopsy would be nice but these rashes are fleeting and dermatologists are hesitant to take from where there is no rash. When it pops up again, call them immediately. Share symptoms with your GP. If concerning, have them refer you to rheumatology and/or hematology for further investigation.
The rash isn’t normal. It’s quite marked and autoimmune/vascular appearing. I hope you find answers! Please keep us up to date.
Thank you for all of the help. Will start to journal. Docs all agree it is something to do with autoimmune but cannot find source so far. 
Thinking biopsy would certainly help for diagnosis but by the time they decided that it was already gone!
It’ll come back. I promise. If I were gambling, I’d bet if you walked into a cold room or dropped your hands in ice water that the rash would return. There are 2 types of livedo. Reticularis and racemosa. Reticularis is associated with a number of things including just straight up lupus. Racemosa which is what yours looks like - broken not lacy - is more associated with APLS. You may have APLS without lupus. They should check these labs beyond just ANA which could be negative. Don’t let them stop there.
I could be very wrong but my intuition has served me very well. Let us know what the testing shows.
I will inquire at my next appointment! Thank you!! Appreciate it very much!!
ANA results came back today “positive” ...
Aaaaaaw fluffers. Well at least you caught it early. Smart on you to have the rash looked at. A positive ANA could represent many things so they’ll send off a whole bunch of other tests to help narrow what’s causing your symptoms and rash. Your doc may refer you to a rheumatologist for further evaluation.
Don’t worry too much. Easier said than done. Your docs will guide you in the right direction. And you have many many friends here! These ladies and few gents are awesome and knowledgeable!
Still waiting on a few more test results but this certainly sheds a little light on things! Thank you for mentioning it. I will have to do a little reading and plan to see doc again in a few weeks. I will inquire about rheumatologist. Appreciate your thoughts and helpful ideas as this is all so very new and I am learning so much!
Testing for lupus right now, reviewing results soon and checking organs. I noticed a photo on a post that looked similar that was on the community that google located - so I thought it might be worth inquiring! Unlike many of the others, this was the first symptom I have ever had. Bites, stings, and general reactions have been already ruled out - wish it was as simple as a food allergy or a bug bite! 
Docs are thinking it has to do with autoimmune system and lupus is on the short list.
It is impossible to "diagnose" a skin rash from a photograph! Skin rashes are notoriously difficult to diagnose, which is why a dermatologist is necessary.
It looks as if the rash is only in a specific area. Livedo Reticularis, encompasses the entire area. It looks very angry & red. Was it "raised"?
It looks as if the sun has penetrated your slacks & the skin has objected. Did your slacks have any pattern on them? Were the slacks tight or loose?
I don't think you should worry too much. Keep a journal ad record any unusual symptoms. You could also ask to see a dermatologist, who is in a far better position to offer advice than Urgent Care! Should this happen again, ask to see a dermatologist and show him/her the pictures.
The fact that all the usual blood tests were OK & it disappeared over night, sounds as if this was caused by sensitivity to the sun - but I am not a medical doctor.
With good wishes,
Ros
Not raised, all under the skin. No pattern on slacks, solid black. Urgent Care did see the actual area but did not do a biopsy - that was the only wish the doctors at full visit really wanted, that they would have biopsied the area. Had additional tests yesterday, checking organs with ultrasound, wont get results back for a few days until they can be read. Joints and muscles are achey this week, been taking ibuprofen. Not sure on blood work, results are coming back but would need doc to interpret all of them.
Lupus admin is right - you’ve had blood tests, medics aren’t worried. It is one of the joys of an immune system working against you. Relax or you can be lead into so many different diagnosis’s and cause yourself stress that Lupus feeds on.
Agree, there is certainly stress! Hoping for the best. Body seems fatigued and sore days following. Taking it easy. Thank you everyone for your help! This last week has been an unfamiliar road.
Aaaaw Fluffers. You’ll get answers soon. Waiting is definitely the worst part. I hope it all comes back negative but if it doesn’t, we are here for you! Unfamiliar roads are the worst but teach us the most.
Please keep us up to date with how things are going. Many hugs your way. ❤️
Hello,
I get the same thing. It happens from heat, not UV rays or crossing your legs, just heat. It’s been happening to me in the sauna for years now & drs can’t diagnose it. It also happens when I’m outside in the heat, but I can be in the shade & my skin covered with clothing & I still get the rash, so it’s not UV (although that’s the only advice I get from drs: wear sunscreen).
At first I thought it was Livedo reticularis because that’s what it looks like. But that’s caused by cold, not heat. (Although I do have Raynaud’s, it affects my hands & feet; I get the rash on my legs & arms). Then I thought it was Erythema ab igne (also known as hot water bottle rash) but I’m told that is more long lasting; mine resolves within an hour.
I have nearly all the symptoms of lupus but not the bloodwork to show a lupus diagnosis. I have a positive ANA & have been diagnosed with undifferentiated connective tissue disease. I’ve seen numerous dermatologists, rheumatologists & general practitioners regarding the rash but I’m not getting a clear answer.
The last dermatologist said she thinks they are Bier spots, but that doesn’t seem correct either. They all say no permanent damage is being done, which I believe is true.
Please do think it through if you really want them to do a biopsy for this rash. I’ve had skin punch biopsies on my leg & foot (for different reasons) and they took months to heal. I couldn’t wear a normal shoe on my foot for over 2 months. It’s not a simple process like drawing blood that heals in a matter of minutes. Just be aware before you agree to go that route.
My guess is this will happen again, but only when your skin reaches a certain temperature. I don’t avoid going in the heat, I just get out of it if I feel my skin burning. And when I say “burning”, it’s completely different than a UV ray sunburn! I have very fair skin & have had 100s of sunburns in my life. This rash is coming from the *inside*, not the surface of the skin & it goes away when the temperature underneath your skin cools down. (This is just my explanation, nothing I was told).
I do hope you find an answer but like the others say, I suggest you don’t worry about it too much. Pay attention to your other symptoms and absolutely keep a journal & photos.
I don’t agree that it’s impossible to diagnose rashes from a photo & so far all the dermatologists have seemed to know less about skin rashes than I do, just from my research online. Drs do not always know the answers & I feel it’s always best to do your research & be your own advocate. I posted my photos here because like you, I wasn’t finding answers elsewhere & started looking for photos of similar rashes.
The good thing is although it seems odd & maybe a little alarming at first, it’s not painful & it goes away quickly. I wish my other symptoms were like that! 
This happened to me twice for the first time this year, I was wearing black jeans too, I’m already being investigated for auto immune but this is now a new one to add to my next appointment...I’ve apparently had a positive anti phospholipid test but this hasn’t been followed up yet..
I realize this is an old thread, but just had to comment to say I just experienced the exact same thing. Note: I have no diagnosis of Lupus/APS/connective tissue disorder, but I am dealing with a bout of Frozen Shoulder (Adhesive Capaulitis) which some scientists think might be a type of auto-immune disorder.
Also I am taking 400mg Advil every 4-6 hrs plus a 650mg 8hr extended-release "Tylenol Arthritis" to deal with the pain. I'm wondering if the NSAIDs could have made me more photosensitive, and my pants (dark gray colored) were just such thin material that the sun came right through.
Similar to Midori7103 above, I thought Levido Reticularis made no sense b/c my rash was brought on by heat, not by cold. Levido Rasemosa could still be the culprit, I guess. But I don't think my rash looks quite like the examples I see online.
I really thought it might be Erythema Ab Igne despite it not looking quite like the pictures, except that my rash faded away quickly: I noticed it at 2:30pm (after sitting with the sun on my lap from 1-2pm) and only one tiny dot was left when I went to sleep at 1am.
I had the brightest rash on my inner thigh (I was sitting with my legs open, "criss cross applesauce style"), but I also had paler rashes on other parts of my legs that had also been in the sun. The top half of my body was shaded and not directly in the sun.
Not what you're looking for?
You may also like...
So as I have predicted my brother his wife and children have dropped out of my wedding
Unbelievable
I'm new to this, wondering if this is flare
Red and Dry
HYDROXYCHLOROQUINE
Related Posts
Don't understand Lupus results
CNS Lupus & Noise Sensitivity
Utter Despair!
Unsure if have lupusModeration team
