A 65-year-old man comes to your office for the evaluation of lower back pain. For the past 3 days, he has had a sharp, burning pain in his left lower back, which would radiate to his flank and, sometimes, all the way around to his abdomen. The pain comes and goes, feels like an “electric shock,” is unrelated to activity, and can be severe. He has had no injury to his back and has no history of back problems in the past. He denies fever, urinary symptoms, or gastrointestinal symptoms. Upon examination you note he has a rash is in the area of the pain. On examination he has an eruption consisting of patches of erythema with clusters of vesicles extending in a dermatomal distribution from his left lower back to the midline of his abdomen. 

• What is the probable diagnosis?
• What are other possible diagnoses?
• At this stage of the case study, what diagnostic studies and basic treatments are most appropriate to order and why?

How to Write a Case Study Paper on Herpes Zoster (Shingles) Presenting as Acute Lower Back Pain

Introduction

Begin the paper by introducing the patient’s presenting complaint and explaining that lower back pain has a broad differential diagnosis ranging from musculoskeletal disorders to neurologic, infectious, renal, and gastrointestinal conditions. State that a careful history and physical examination are essential in narrowing the diagnosis. Explain that the appearance of a unilateral vesicular rash in a dermatomal distribution strongly suggests an infectious etiology rather than a musculoskeletal cause. Briefly indicate that the discussion will identify the most likely diagnosis, explore alternative diagnoses, and recommend appropriate diagnostic studies and initial treatment based on current clinical guidelines.

Section 1: Determine the Probable Diagnosis

Identify the most likely diagnosis as herpes zoster (shingles) caused by reactivation of the varicella-zoster virus.

Explain why this diagnosis is the most appropriate by connecting the patient’s symptoms to the classic clinical presentation. Discuss the patient’s age, unilateral sharp burning pain, electric shock-like sensation, dermatomal distribution, grouped vesicles on an erythematous base, and absence of systemic symptoms. Explain that neuropathic pain often develops several days before the rash appears because the virus reactivates within the dorsal root ganglion and travels along the affected sensory nerve. Discuss how the localization of the rash to one dermatome without crossing the midline is characteristic of herpes zoster.

Include discussion of risk factors such as advanced age, declining cell-mediated immunity, immunosuppression, stress, malignancy, and chronic illnesses that increase the likelihood of varicella-zoster virus reactivation.

Section 2: Discuss Other Possible Diagnoses

Present the important differential diagnoses and explain why each is less likely than herpes zoster.

Discuss lumbar radiculopathy caused by lumbar disc herniation, noting that radicular pain may resemble neuropathic pain but does not produce a vesicular dermatomal rash.

Discuss nephrolithiasis because flank pain can radiate toward the abdomen. Explain that kidney stones usually present with hematuria, nausea, vomiting, restlessness, or urinary symptoms rather than grouped vesicles.

Discuss cellulitis and contact dermatitis, explaining that these skin conditions may produce erythema but lack the characteristic unilateral dermatomal vesicular eruption and neuropathic pain.

Consider herpes simplex virus infection, noting that HSV typically recurs in localized mucocutaneous regions and is less likely to follow a single dermatome.

Include pyelonephritis, musculoskeletal lower back strain, spinal stenosis, abdominal aortic aneurysm, biliary disease, and thoracic radiculopathy as additional differential diagnoses depending on the clinical presentation.

Explain why each alternative diagnosis is less consistent with the patient’s history and physical examination findings.

Section 3: Recommend Appropriate Diagnostic Studies

Explain that herpes zoster is primarily a clinical diagnosis, and additional testing is usually unnecessary when the presentation is classic.

Discuss situations in which laboratory confirmation may be appropriate, including immunocompromised patients, atypical lesions, disseminated disease, recurrent infections, or diagnostic uncertainty.

Describe appropriate diagnostic studies that may include:

Polymerase chain reaction (PCR) testing of vesicular fluid as the preferred confirmatory test because of its high sensitivity and specificity.

Direct fluorescent antibody testing if PCR is unavailable.

Viral culture, while explaining its lower sensitivity compared with PCR.

Tzanck smear, noting its limited usefulness because it cannot distinguish herpes simplex virus from varicella-zoster virus.

If indicated, discuss ordering a complete blood count, comprehensive metabolic panel, HIV screening in selected patients, urinalysis if renal pathology remains a concern, or imaging studies only when another diagnosis is strongly suspected.

Explain why routine imaging studies such as lumbar spine MRI or CT are unnecessary when the clinical findings clearly indicate herpes zoster.

Section 4: Recommend Initial Treatment and Management

Discuss evidence-based treatment recommendations.

Explain that antiviral therapy should begin as early as possible, ideally within 72 hours of rash onset, to reduce symptom severity, shorten disease duration, and decrease the risk of postherpetic neuralgia.

Discuss recommended antiviral medications, including acyclovir, valacyclovir, and famciclovir, with preference for valacyclovir or famciclovir because of improved dosing convenience and bioavailability.

Describe pain management strategies, including acetaminophen, nonsteroidal anti-inflammatory drugs, and opioid medications for severe pain when appropriate.

Discuss medications specifically used for neuropathic pain, including gabapentin, pregabalin, tricyclic antidepressants, and topical lidocaine preparations if pain persists.

Explain that corticosteroids may occasionally be considered in carefully selected immunocompetent patients with severe acute pain when combined with antiviral therapy, although they should never be used as monotherapy.

Include patient education regarding skin care, avoiding scratching lesions, maintaining lesion cleanliness, covering the rash until crusting occurs, practicing appropriate hand hygiene, and avoiding contact with pregnant women, immunocompromised individuals, and persons without immunity to varicella while lesions remain infectious.

Discuss follow-up care to monitor symptom resolution, medication adherence, complications, and the possible development of postherpetic neuralgia.

Finally, recommend administration of the recombinant zoster vaccine after recovery in eligible adults to reduce the risk of future herpes zoster episodes.

Conclusion

Conclude by emphasizing that the patient’s unilateral burning pain followed by a dermatomal vesicular eruption is highly characteristic of herpes zoster. Reinforce that although several conditions may mimic the early symptoms, the physical examination findings make shingles the most probable diagnosis. Explain that the diagnosis is primarily clinical, with PCR reserved for atypical presentations or diagnostic uncertainty. Conclude by highlighting that prompt initiation of antiviral therapy, effective pain management, patient education, and appropriate follow-up are essential for reducing complications and improving patient outcomes.

References

Centers for Disease Control and Prevention. (2024). Clinical overview of shingles (herpes zoster).

Dunphy, L. M., Winland-Brown, J. E., Porter, B. O., & Thomas, D. J. (2023). Primary care: The art and science of advanced practice nursing.

James, W. D., Elston, D. M., Treat, J. R., Rosenbach, M. A., & Neuhaus, I. M. (2024). Andrews’ diseases of the skin: Clinical dermatology.

Papadakis, M. A., McPhee, S. J., & Rabow, M. W. (2025). Current medical diagnosis & treatment.

Whitley, R. J., & Gnann, J. W. (2023). Herpes zoster. The New England Journal of Medicine.

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