Notalgia paresthetica (NP), also known as hereditary localized pruritus of the shoulder, posterior pigmentic pruritic patch (4 P), subscapular pruritus, localized shoulder pruritus, is a common localized chronic pruritus on the mid back skin.

The term derived from the Greek notos meaning “back”.

NP is seen worldwide, in all races, in adulthood (mature and older adult subjects, mean age 50-60 years), more frequent in women (sex ratio of around 2:1 F:M).

Two are the main diagnostic criterions:

• Specific area of the symptoms

• Pruritus

Unilateral, it mainly affect the area below the shoulder blade (mid to upper back), just past easy reach, corresponding D2-D6 dermatomes.

The characteristic symptom is pruritus (sensation that makes a person want to scratch), intermittent, often paroxysmal, varying in intensity. It can occasionally accompanied by paresthesia (skin sensation such as burning, pricking, itching or tingling) and/or hypersthesia (unusual increased sensitivity of the skin to sensory stimuli, such as pain, abnormal heating, cold or touch sensations).

The affected area shows a well ill-defined circumscribed pigmented macula, non indurated, ranging from 3-10 cm.

NP tends to be a chronic condition with periodic remissions and exacerbations.

NP is common but however is often underrecognized and underdiagnosed.

It’s not life threatening but can decrease quality of life causing discomfort and nuisance.

The cause of NP is not completely defined and multiple causes are purposed.

In the hereditary localized pruritus of the shoulder, the cutaneous symptoms represent and early clinical marker. Several cases have been accompanied by multiple endocrine neoplasia type 2A (MEN-IIA), transmitted via autosomal-dominant inheritance mechanisms, with an age of onset in infants and adolescents and less frequently in young adults.

But the majority of NP patients show a high association with cervical  and dorsal spinal disease tracing back to a chronic sensory neuropathy in which early spinal nerve impingement may contribute to its pathogenesis.

Radiographic changes in the vertebrae tend to correspond to the dermatome of the cutaneous lesion. Spinal disorders include ostoarthrosis, vertebral hyperostosis, spinal static disequilibrium.

In the past patient’s history there can be findings of osteoarthritis, prior neck trauma, motor vehicle accident, vertebral fracture, cervical disk disease.

Skin histopathology shows a postinflammatory hyperpigmentation. Usually amyloid-specific staining is negative. If amyloid is detected, it is caused by irritation, as a conseguence of degradation of keratin into amyloid.

The treatment of NP in patients with underling spinal disease is based on management of spinal disease ( spinal physiotherapy).

Many treatments have been tried:

• Local anesthetics (EMLA)

• Topical corticosteroids

• Topical capsaicin

• Hydroxyzine

• Nerve blocks

• Epidural injections

• Acopunture

• Botuline toxin injections