Sparing phenomena in dermatology.

Despite considerable overlap, the confusion hovering over the four common sparing signs can be cleared as follows: Reverse Koebner relates to sparing by physical trauma; isotopic non-response/reverse isotopic response relates to sparing over an already healed dermatosis; Renbok Phenomenon relates to sparing among two concomitant active diseases often with autoimmune etiology; anatopic phenomenon relates to sparing caused by presence of certain infectious diseases of skin. In conclusion, sparing phenomenon of dermatology seems to command our attention by their sheer number, variety, and clinical implications. Therefore, it may be said that astute clinician is the one who will look, not only for the presence of lesions in the patient but also for the conspicuous absence thereof.