Localized cutaneous sensory abnormalities in dermatome is a diagnostic clue to presense of prodromal pain
Older Patient present typical dermatomal rash and pain.
ESSENTIAL DIAGNOSIS
~Pain along the course of a nerve followed by grouped vesicular lesions.
~Involvement is unilateral; some lesions (< 20) may occur outside the affected
dermatome.
~Lesions are usually on face or trunk.
In the Shingles Prevention Study of 1308 cases of suspected herpes zoster. 984 confirmed(75%).
In rash phase herpes simplex has the most similar presentation to herpes zoster. Evidence to support herpes zoster are
~ older population
~ no multiple reoccurences
~ presence of chronic pain
Herpes zoster occurs in areas mainly affected by herpes simplex (oral, genitals, buttocks)
HIV-infected patients are 20 times more likely to develop zoster, often before other clinical findings of HIV disease are present.
A history of HIV risk factors and HIV testing when appropriate should be considered, especially in patients with zoster who are younger than 55 years.
LABORATORY TEST
Needed when differentiating herpes zoster and herpes simplex is necessary and in atypical presenation case.
Best specimen- vesicle fluid- abundant VZV
-IF NOT POSSIBLE - lesion scraping, crust, tissue biopsy and cerebrospinal fluid
VZV antigen detection by IFA from vesicle scraping or tissue biopsies take hours but specific and sensitive- most useful
PCR is highly sensitive and specific, so can teat crust and other samples, its cost decreasing- will be common
IgM and IgG useful in retrospective diagnosis when there is no adequate sample.
Tzank smear suggest Herpes Zoster when multinucleated giant cells and intranuclear inclusions are seen on slides but does not differentiaite herpes zoster and herpes simplex.
SOURCE:
Twersky J., Schmader K., Hazzard's Geriatric Medicine and Gerontology, 6e , Chapter 129: Herpes Zoster
Berger T., Current Medical Dx & Tx,Chapter 6: Deramtalogic Disorders, Vesicular Dermatoses, Herpes Zoster(Singles)
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