What histologic findings most commonly lead you to order additional staining for potential desmoplastic melanoma?

I am pretty liberal on ordering IHC stains to rule invasive melanoma in or out. If I see anything questionable like atypical or spindled cells in the dermis, I will order for sure. However, I often do SOX10 and PRAME on MIS biopsies to help with margins, so I usually have them done in most cases any...