PRACTICE RECOMMENDATIONS
• Reserve laboratory testing for unclear or complicated cases of herpes zoster (HZ), as the condition can be diagnosed clinically in most cases. B
• Whenever possible, initiate oral antiviral therapy within 72 hours of the onset of the shingles rash to accelerate healing and reduce the duration and severity of pain. A
• Offer the HZ vaccine (Zostavax) to patients ages 60 and older to reduce the risk of shingles and postherpetic neuralgia. A
Strength of recommendation (SOR)
A Good-quality patient-oriented evidence
B Inconsistent or limited-quality patient-oriented evidence
C Consensus, usual practice, opinion, disease-oriented evidence, case series
CASE Jane T, a 53-year-old patient, calls her family physician’s office for a same-day appointment; she has severe right upper quadrant pain that developed a few hours ago. When Jane comes in, she tells her physician that the pain feels like the gallbladder attacks she used to have—before her gallbladder was removed 2 years ago. She has nausea but no vomiting, is afebrile, and has no urinary symptoms.
A series of in-office tests—urinalysis, complete blood count, comprehensive metabolic profile, amylase, and lipase— are all normal. The physician gives Jane an intramuscular injection of ketorolac and a prescription for oral tramadol, and sends her for a right upper quadrant ultrasound, which is also normal. The next morning, the pain intensifies, and Jane goes to the emergency department, where she undergoes computed tomography of the abdomen and pelvis—also normal. After a night in the hospital for observation, she is released. She returns to the family physician 3 days later, this time with an erythematous papular rash in a dermatomal distribution over her back and right upper quadrant that her doctor immediately recognizes as shingles.
Jane is not alone. Each year, about 1 million US residents develop herpes zoster (HZ),1 and 70% to 80% of them experience prodromal pain in the affected dermatome.2 For some, the pain is significant enough to prompt a medical work-up to rule out other potential causes, such as myocardial infarction, nephrolithiasis, pancreatitis, cholecystitis, and appendicitis.
The time and resources spent on such a work-up may be unavoidable when a patient presents with severe pain. But alert primary care physicians can avoid unnecessary diagnostic tests by being aware of the prodromal symptoms of HZ and being on the lookout for the rash that follows.
Age alone is a key factor in the detection of HZ, of course. One in 3 people will develop shingles during their lifetime,1 with half of all cases occurring in people ages 60 and older.3 In addition to early detection and treatment, physicians can do their part to battle HZ by routinely recommending the shingles vaccine (Zostavax) to patients in this age group.
Diagnosing HZ: From prodrome to rash
For many patients, an abnormal skin sensation on one side of the body, such as itching, burning, or altered sensitivity to touch, is the first symptom of HZ. These sensations, including pain that can range from mild to severe, may precede the rash by days or even weeks.4 Systemic symptoms are far less common; less than 20% of patients develop fever, headache, malaise, or fatigue as part of the HZ prodrome.2
The shingles rash is usually unilateral and does not cross the midline. However, it may occur in up to 3 adjacent dermatomes. The trunk is the most common site for the rash, but it may also develop on the face, buttocks, or other parts of the body. The lesions start as erythematous papules and evolve into vesicles within 12 to 24 hours.5
Once the rash emerges, HZ can usually be diagnosed clinically in a primary care setting, and laboratory testing should be considered only when diagnosis is uncertain. In a cohort study of 260 patients older than 50 years with clinically diagnosed HZ, 236 (91%) cases were confirmed on serologic testing.6 In an Icelandic study, 93% of 505 cases were diagnosed correctly by general practitioners, using expert opinion and clinical course as the gold standard.7
If diagnostic testing is necessary, physicians have a number of choices:
Varicella zoster polymerase chain reaction (PCR) test. PCR testing for HZ can provide rapid and reliable diagnosis and is becoming more widely available, but its use should be limited because of the cost (approximately $300).
Tzanck smear. This test is quick and inexpensive, and can reliably diagnose a herpetic lesion based on the presence of acantholytic and multinucleated giant cells in a sample collected from the base of a vesicle.8 However, this technique cannot differentiate HZ from herpes simplex infection, and lack of experience with collection or interpretation of the Tzanck smear limits its usefulness.