I itch---a lot. Mrs. Pal swears it's scabies, impetigo, or some other horrible and embarrassing contagion. I suggested body lice, to which she replied, "There's such a thing as body lice? Ech! Sleep in the guest room!"
It's not any of those things (thank Asclepius), but I'm gaining a new level of empathy for patients with rashes. Luckily I was able to carve a chunk of time out of my schedule tomorrow to head over to the dermatologist, a specialty for which I suddenly have a renewed respect. (I'm betting on guttae psoriasis, which means it cannot be guttae psoriasis).
Rashes are a fascinating area of medicine. The skin is incredibly complex, forming a physical barrier between our important bits and the environment, but also a living shield patrolled by immune cells who mark and attack invaders and create a cellular memory to defend against future attacks. Diseases that injure this barrier open us up to horrible infections. Burn patients often die of fluid loss and overwhelming infections, but any significant injury to the skin can have similarly bad results.
Being so immunologically active, the skin is susceptible to "friendly fire", where our own immune system either attacks the skin or causes uncomfortable reactions (among these are common diseases such as psoriasis, hives, and eczema). Skin contains many different kinds of cells, and something can go wrong with all of them. Skin cancers are very common, especially the "benign" sorts like basal and squamous cell cancers. Cancers of skin pigment cells, called malignant melanomas, are often deadly.
The complexity of skin and all the things that can go wrong with it are endlessly fascinating, and endlessly frustrating for internists. To non-dermatologists, just about all rashes can look "red and bumpy", a completely un-helpful assessment. But most people with rashes come to see me before they get to a dermatologist, so I constantly work on refining my ability to describe and diagnose skin conditions.
This time of year, I start to see my first cases of rhus phytodermatitis (that's poison ivy---I think dermatologists keep the competition down by giving every thing Greek and Latin names). People are starting to do a little spring cleaning and the classic "leaves of three, let them be" aren't out yet, just vines and stems covered in nasty urushiol. It should be at least another month or two before I start seeing mosquito bites (yes, people come to the doctor for them) and sun burns.
I'm pretty good at spotting psoriasis, seborrheic dermatitis, eczema, and other common rashes, but when it comes to skin, it's not that hard to stump me. I might not always know what a rash is caused by, but I usually know when I need to refer to an expert, and right now I'm counting on benadryl to keep me going until tomorrow.