Scleredema diabeticorum is a chronic condition caused by deposition of mucin into the deep cutaneous tissues (primarily the reticular dermis) that classically occurs on adult males with diabetes mellitus. The onset is described as insidious, beginning with erythema and perhaps a feeling of tightness, which then graduates to induration and thickening of the skin of the upper back, primarily. Although it can, in rare cases, restrict the expansion of the thorax in respiration, it usually does not.
The histopath on the biopsies taken from these folks is often pretty obvious, because the collagen fibers are widely separated by mucin, but occasionally you have to finesse a biopsy by using an unfixed specimen and staining it with Toluidine Blue, a stain which is very good at detecting mucin (it looks magenta). Of note, there is no sclerosis (increased collagen) and there is no edema, per se.
There are subtypes of scleredema, which are as follows: Those associated with preceding illness such as a strep pharyngitis, NAR (No Apparent Reason) and those associated with diabetes. The NARs often have a monoclonal gammopathy. Always make sure their internist knows about the gammopathy association, so they can check an SPEP.
Many of you called this scleroderma diabeticorum, and I tried to prod each of you to check (and in some cases, recheck) your spelling. This disease is NOT related in any way to scleroderma. I gave you credit even if your spelling was a little off. You just misread the name, understandably so.
For a bonus point, who is in the polka-dotted jersey in the TdF as of Sunday, July 8th, and what does that signify?
All of you should pat yourself on the back for nailing this one, in that this patient had a hard, carapace-like induration that had been multiply evaluated by dermatologist, all of whom missed the answer. Take a bow, and take the time to tell your significants how smart you are. They need to know.