Prurigo Nodularis
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Direct answer
Prurigo nodularis is a chronic, intensely pruritic disorder of firm, hyperkeratotic nodules, typically on the extensor surfaces of the limbs and the back. The nodules develop from long-standing scratching, with neural and immune changes in the skin sustaining the itch. Systemic causes such as chronic kidney disease, iron deficiency, liver disease and HIV must be sought, and treatment combines potent topical steroids and phototherapy with biologics for moderate-to-severe disease.
What you must remember
- Morphology: firm, hyperkeratotic, excoriated nodules, usually 0.5 to 2 cm across, which itch intensely and are often crusted.
- Distribution: symmetrical on the extensor arms and legs and the back, usually sparing the face and mucous membranes.
- Pathogenesis: chronic itch with neural hyperplasia and immune activation, including the IL-31 and IL-4 and IL-13 pathways.
- Systemic associations: chronic kidney disease with uraemic itch, iron deficiency, liver disease, HIV, thyroid disease and diabetes.
- Psychiatric overlap: anxiety, depression and obsessive-compulsive features are common, and they amplify the scratch cycle rather than explaining it alone.
- Local first line: potent topical corticosteroids under occlusion, emollients and intralesional triamcinolone for individual nodules.
- Escalation: narrowband UVB phototherapy, neuromodulators such as gabapentin for refractory itch, and biologics for moderate-to-severe disease.
A systematic approach to the itch
Prurigo nodularis succeeds only when the itch is controlled, so management moves from the underlying cause to the individual nodule. Each step should be documented, because nodules recur whenever the itch persists.
- Search for systemic causes: check renal function, iron studies, liver function, thyroid function and HIV status. Screen for depression and anxiety at the same time.
- Stop aggravating factors: review drugs such as opioids, and address dry skin, hot bathing and nocturnal scratching.
- Break the scratch loop: apply emollients and occlusion at night, and cover the nodules to limit mechanical trauma.
- Treat individual nodules: intralesional triamcinolone reduces resistant nodules, while potent topical steroids are applied to the wider plaques.
- Add phototherapy: narrowband UVB is given several times a week for patients who do not settle with topical therapy.
- Use systemic and biologic therapy: neuromodulators are used off-label for refractory itch, and biologics that target the IL-4, IL-13 or IL-31 pathways are reserved for moderate-to-severe disease.
Biologic licensing varies between countries, so the local regulatory position and cost should be checked before treatment is planned.
Where the exam tries to catch you
Prurigo nodularis questions test the cause-first approach, the systemic associations and the mimics.
- Trap: treating only the nodules and ignoring the cause Correct: the nodules recur while the itch persists, so systemic and psychiatric causes must be addressed alongside local treatment.
- Trap: labelling prurigo nodularis as purely psychogenic Correct: it has real neural and immune drivers, and psychological support is an adjunct, not the diagnosis.
- Trap: mistaking the nodules for nodular scabies without checking Correct: nodular scabies favours the genitals and groin, and a scraping or biopsy separates the two when the pattern is unclear.
- Trap: starting long courses of systemic steroids Correct: topical therapy, phototherapy and targeted biologics are preferred over prolonged systemic steroid use.
Frequently asked questions
Which systemic diseases are linked to prurigo nodularis?
Chronic kidney disease with uraemic itch, iron deficiency, chronic liver disease, HIV infection, thyroid disease and diabetes are linked to prurigo nodularis. Psychiatric comorbidity such as anxiety, depression and obsessive-compulsive features is also common. Screening for these conditions is part of the standard work-up.
Which phototherapy is used in prurigo nodularis?
Narrowband UVB is the phototherapy most often used for prurigo nodularis, given several times a week over a course. It can reduce both itch and nodule size in many patients. It is usually considered when topical therapy has not controlled the disease.
What is the first-line local treatment for prurigo nodularis nodules?
Potent topical corticosteroids under occlusion, emollients and intralesional triamcinolone for individual nodules form the usual local approach. Topical capsaicin is an additional option for some patients. The aim is to break the scratch cycle while the systemic cause is addressed.
Which biologics are used in prurigo nodularis?
Biologics that target the IL-4 and IL-13 pathway, such as dupilumab, and the IL-31 pathway are licensed for moderate-to-severe prurigo nodularis in several countries. They are reserved for patients who have not responded to topical, phototherapy and systemic measures. Local licensing and cost determine their use in India.
How does prurigo nodularis differ from nodular scabies?
Prurigo nodularis forms firm, symmetrical nodules on the extensor limbs and back, whereas nodular scabies favours the genitals, groin and axillae. A skin scraping or biopsy can show scabies mites or characteristic features when the pattern is unclear. Scabies contacts in the household should also be treated.