https://www.reddit.com/gallery/q58hrk
Severe allergy and can’t find what’s causing it. Literally have tried EVERYTHING. Have been on 5 rounds of steroids in the past 2 months. Saw an allergist and having a patch test done so have to stop steroids and that’s the only thing giving me relief. I will try anything at this point.
After swelling goes down skin is dry, itchy, feels hot, and red. Nothing is helping. I want to crawl in a hole and never come out–I think I hear this story every day and definitely feel for those of you that suffer from CONTACT DERMATITIS. Click on the link if you want more information from American Contact Dermatitis Society. As this gal is appropriately pursuing, you must do patch testing for better answers.
Bailey E, Kroshinsky D. Cellulitis: diagnosis and management. Dermatol Ther. 2011 Mar-Apr;24(2):229-39. doi: 10.1111/j.1529-8019.2011.01398.x. PMID: 21410612.Cellulitis is an acute infection of the dermal and subcutaneous layers of the skin, often occurring after a local skin trauma. It is a common diagnosis in both inpatient and outpatient dermatology, as well as in the primary care setting. Cellulitis classically presents with erythema, swelling, warmth, and tenderness over the affected area. There are many other dermatologic diseases, which can present with similar findings, highlighting the need to consider a broad differential diagnosis. Some of the most common mimics of cellulitis include venous stasis dermatitis, contact dermatitis, deep vein thrombosis, and panniculitis. History, local characteristics of the affected area, systemic signs, laboratory tests, and, in some cases, skin biopsy can be helpful in confirming the correct diagnosis. Most patients can be treated as an outpatient with oral antibiotics, with dicloxacillin or cephalexin being the oral therapy of choice when methicillin-resistant Staphylococcus aureus is not a concern–and yes, sometimes you have to treat with the antibiotic and see if the condition improves. That’s why we call this the “practice of medicine”
Roy S, Chompunud Na Ayudhya C, Thapaliya M, Deepak V, Ali H. Multifaceted MRGPRX2: New insight into the role of mast cells in health and disease. J Allergy Clin Immunol. 2021 Aug;148(2):293-308. doi: 10.1016/j.jaci.2021.03.049. Epub 2021 May 4. PMID: 33957166; PMCID: PMC8355064.
Mast cells are getting lots of attention these days and many mystery diagnoses are labeled as “mastocytosis”. For the unfortunate few with true mastocytosis, your life will be filled with hives, flushing just like the above picture. At times, you may need chemotherapy if your tryptase levels get too high. But most patients (and doctors alike) who think they have mastocytosis really don’t.
Cutaneous mast cells (MCs) express Mas-related G protein-coupled receptor-X2 (MRGPRX2; mouse ortholog MrgprB2), which is activated by an ever-increasing number of cationic ligands. Antimicrobial host defense peptides (HDPs) generated by keratinocytes contribute to host defense likely by 2 mechanisms, one involving direct killing of microbes and the other via MC activation through MRGPRX2. However, its inappropriate activation may cause pseudoallergy and likely contribute to the pathogenesis of rosacea, atopic dermatitis, allergic contact dermatitis, urticaria, and mastocytosis. So here’s the link between normal cells in the body and disease of any kind: inappropriate activation causes a rash you don’t want to deal with. Gain- and loss-of-function missense single nucleotide polymorphisms in MRGPRX2 have been identified. The ability of certain ligands to serve as balanced or G protein-biased agonists has been defined. Small-molecule HDP mimetics that display both direct antimicrobial activity and activate MCs via MRGPRX2 have been developed. In addition, antibodies and reagents that modulate MRGPRX2 expression and signaling have been generated. In this article, we provide a comprehensive update on MrgprB2 and MRGPRX2 biology. We propose that harnessing MRGPRX2’s host defense function by small-molecule HDP mimetics may provide a novel approach for the treatment of antibiotic-resistant cutaneous infections. In contrast, MRGPRX2-specific antibodies and inhibitors could be used for the modulation of allergic and inflammatory diseases that are mediated via this receptor.
So for contact dermatitis, remember the following:
- You can always have an infection that mimics contact dermatitis–don’t forget to at least ask about antibiotics.
- Facial rosacea is treated with topical metronidazole among other creams, but it often hangs around for a long time. It will mimic contact dermatitis many times.
- Patch testing is crucial for diagnosing the culprit causing contact dermatitis, and I would recommend having this procedure done at a clinic familiar with patch testing and even consider customizing your own patch test. We do this in our clinic with use of a Finn Chamber which allows you to test for anything in a semi-liquid or pasty consistency.
- Autoimmunity can always cause a rash, especially on the face and upper body. Anyone see a butterfly rash that looks like this?
I hope she gets some answers and I’d love to hear about your stories re: facial rash and contact dermatitis.
TulsaAllergyNews 