Itchy rash on back
A 69-year-old woman with a history of basal cell carcinoma presented to the Family Medicine Skin Clinic with a left scapular rash of 4 years’ duration. It started as a small patch of pruritic skin that subsequently developed hyperpigmentation after intensive scratching. The patient was otherwise healthy and denied any constitutional symptoms.
What’s your diagnosis?
A unilateral, neuropathic itch accompanied by postinflammatory pigmentation changes or lichenification at the medial inferior tip of the scapula are the hallmarks of notalgia paresthetica (NP).
NP is thought to result from nerve impingement or chronic nerve trauma to the posterior rami of the upper thoracic spinal nerves. The hyperpigmentation and lichenification arise from repeated scratching or rubbing of the skin.
NP is a clinical diagnosis and does not require biopsy or imaging. The differential diagnosis includes brachioradial pruritus, postherpetic neuralgia, multiple sclerosis, and other small fiber neuropathies.
The standard treatment is topical capsaicin 0.025% tid for 5 weeks, with repeat treatments (for a few days or weeks) if there are relapses. Higher doses (0.075%) may work more quickly but may also lead to more burning. A lidocaine 5% patch bid can also be considered. Second-line treatment options include cutaneous electrical field stimulation or transcutaneous electrical nerve stimulation, gabapentin, or oxcarbazepine. Topical steroids are considered ineffective for this condition.1
The patient in this case was started on capsaicin 0.025%. She was encouraged to keep her skin moisturized and well hydrated because dyshidrosis can exacerbate itching. A prescription for gabapentin was offered in case topical treatments were unsuccessful, but she declined after she weighed the risks of adverse effects against her current symptoms.
Photo courtesy of Daniel Stulberg, MD, and text courtesy of Nathan Birnbaum, MD, and Daniel Stulberg, MD, FAAFP, Department of Family and Community Medicine, University of New Mexico School of Medicine, Albuquerque