Erythema ab igne
Erythema ab igne is a relatively common pigmentary disorder that results from chronic heat, which can either be red (hence "erythema") or brownish red, as in the above example. The reticulated rash is a result of the damage from heat of the superficial vessels, and the hypermelanosis is a result of pigmentary incontinence.
Confluent and reticulated papillomatosis of Gougerot and Carteaud is more scaly and elevated than is erythema ab igne, and is pretty easy to figure out in person.
Congrats, all of you got this one correct. The Challenge this month is too close to call thus far. There are five of you within a point of one another, and another five of you two points back from the leader. There is plenty of time to have this lead change hands, but at present Christine shares the lead with Emily.