Microcystic Adnexal Carcinoma
Rather than belabor the relationship between infiltrative BCCs and MACs, I will instead list what is the reasonable differential diagnosis. I did not count off for wrong answers, but did give credit for right ones. Here's the DDx as accepted by most dermatologists: Scar, MAC, Infiltrative BCC, Desmoplastic trichoepithelioma, post-LN2 hypopigmentation (although I've never seen it look like this) and vitiligo (never seen it look like this, either. For those of you who put regressed MM, I will grant that, although it is entirely atypical for that, but I did not give credit for amelanotic MM, because they are pink or red. I really want to make the point that any scar that is irregular or round on the face demands an explanation, and if no history of trauma exists, then biopsy is indicated.
No infectious causes would be this discrete, and except as above, no inflammatory processes would be, either.