How shingles can be beached

An 85-year-old patient presented with red skin on his forehead, around his eyes, and on the top of his head. The reddened area was covered with clusters of blisters. Shingles was diagnosed. After causing chickenpox, the varicella zoster virus lies dormant in dorsal root ganglia, on the sensory pathway; weakening of the immune system causes the virus to travel down the sensory nerves and manifest as shingles, in a dermatomal distribution. In this man, shingles affected the skin innervated by the ophthalmic division of the trigeminal nerve. However, part of his forehead was spared (figure). 20 years previously, he had developed a basal cell carcinoma on this part of the scalp; the skin excised was replaced by transplanted skin from a buttock. The transplanted skin did not develop shingles, as the sensory pathway was not intact.