Commonest site of involvement of herpes zoster
People with herpes zoster most commonly have a rash in one or two adjacent dermatomes (localized zoster). The rash most commonly appears on the trunk along a thoracic dermatome. Less commonly, the rash can be more widespread and affect three or more dermatomes. This condition is called disseminated zoster Ref Harrison20th edition pg 980 Ref Davidson edition23rd pg 240
Thoracic region
Cranial nerve
Face
Lumbar region
Infection