8.1 Chronic Pruritus, Chronic Prurigo, Dermatoses of Pregnancy & Geriatric Dermatology
Key Takeaways
- Chronic pruritus is itch lasting 6 weeks or longer, and itch without a primary rash needs screening for systemic causes including kidney, liver, thyroid, iron, blood, and malignant disease.
- Pemphigoid gestationis involves the umbilicus, shows linear C3 along the basement membrane on direct immunofluorescence, and is associated with prematurity and small-for-gestational-age babies.
- Polymorphic eruption of pregnancy usually starts in the abdominal striae in the third trimester of a first pregnancy, spares the umbilicus, and carries no fetal risk.
- Intrahepatic cholestasis of pregnancy causes itch without a primary rash, starting on the palms and soles, with raised serum bile acids; stillbirth risk rises markedly at bile acids of 100 micromol/L or more.
- Dupilumab is approved in the EU for moderate-to-severe prurigo nodularis in adults who are candidates for systemic therapy.
8.1 Chronic Pruritus, Chronic Prurigo, Dermatoses of Pregnancy & Geriatric Dermatology
Chronic Pruritus
Chronic pruritus is itch lasting 6 weeks or longer. The International Forum for the Study of Itch (IFSI) groups patients clinically as:
- itch on inflamed skin (eczema, psoriasis, scabies, urticaria);
- itch on non-inflamed skin (no primary lesions);
- itch with chronic scratch lesions (excoriations, lichenification, prurigo nodules).
Causes are then classed as dermatological, systemic, neurological, psychogenic, mixed, or other.
Systemic Causes of Itch Without a Rash
| System | Examples and Clues |
|---|---|
| Kidney | Chronic kidney disease-associated pruritus, worse in dialysis patients |
| Liver | Cholestasis (primary biliary cholangitis, primary sclerosing cholangitis, drugs, pregnancy); itch often starts on palms and soles |
| Blood | Iron deficiency; polycythaemia vera (aquagenic pruritus after bathing, JAK2 V617F); Hodgkin lymphoma (itch with night sweats and weight loss) |
| Endocrine | Hyper- and hypothyroidism, diabetes |
| Infection | HIV, hepatitis C, parasites |
| Drugs | Opioids, hydroxyethyl starch, chloroquine (common in African patients), and many others |
| Neurological | Brachioradial pruritus (outer forearms, linked to sun and cervical spine disease); notalgia paraesthetica (patch below the shoulder blade, T2–T6); post-herpetic itch; multiple sclerosis |
| Psychogenic | Diagnosis of exclusion; linked to anxiety and depression |
Baseline tests for itch without a rash: full blood count with differential, ferritin, kidney and liver function, thyroid function, glucose or HbA1c, and HIV and hepatitis serology when there are risk factors. Consider a chest radiograph and age-appropriate cancer screening, especially in older adults.
Stepwise European Treatment (EDF/EADV chronic pruritus guideline)
| Step | Measures |
|---|---|
| General | Emollients, lukewarm short showers, loose cotton clothing, short nails, breaking the itch-scratch cycle, treat the cause |
| Topical | Cooling agents (menthol, polidocanol), short courses of topical corticosteroids, calcineurin inhibitors, capsaicin (localised neuropathic itch) |
| Systemic by mechanism | Non-sedating antihistamines (mainly for histamine-driven itch such as urticaria); gabapentin or pregabalin (neuropathic, uraemic); mirtazapine or SSRIs (paraneoplastic, psychogenic, nocturnal); naltrexone (cholestatic); rifampicin and bile acid sequestrants (cholestatic); difelikefalin (haemodialysis patients) |
| Phototherapy | Narrowband UVB, useful in uraemic itch and chronic prurigo |
| Biologics | Dupilumab (EU-approved for prurigo nodularis); nemolizumab (anti-IL-31 receptor A) has been approved for prurigo nodularis in the EU |
Chronic Prurigo
Chronic prurigo (CPG) is defined by chronic itch (6 weeks or longer), signs of repeated scratching, and multiple pruriginous lesions (papules, nodules, or plaques). Prurigo nodularis is the nodular form, with symmetric, very itchy hyperkeratotic nodules on the extensor limbs and trunk, sparing the mid-back ("butterfly sign"). It is linked to atopy, chronic kidney and liver disease, HIV, and psychological disease. Treatment follows the itch ladder above, with potent or intralesional steroids, phototherapy, and dupilumab for moderate-to-severe disease.
Specific Dermatoses of Pregnancy
| Condition | Timing | Clinical Features | Investigations | Fetal Risk | Management |
|---|---|---|---|---|---|
| Atopic eruption of pregnancy | Often before the 3rd trimester | Eczematous or prurigo lesions in atopic women; the most common pregnancy dermatosis | Sometimes raised IgE | None | Emollients, topical steroids, antihistamines |
| Polymorphic eruption of pregnancy (PEP) | 3rd trimester or just after delivery; usually first pregnancy; more common in multiple pregnancy | Urticarial papules starting in abdominal striae, sparing the umbilicus | DIF negative | None | Topical steroids, antihistamines |
| Pemphigoid gestationis | 2nd or 3rd trimester, or after delivery | Urticarial plaques around and on the umbilicus, then tense blisters | Linear C3 (± IgG) along the BMZ on DIF; anti-BP180 NC16A antibodies | Prematurity, small for gestational age, mild transient neonatal blisters | Potent topical steroids, systemic prednisolone; recurs earlier in later pregnancies and with hormonal contraception |
| Intrahepatic cholestasis of pregnancy (ICP) | Usually 3rd trimester | Itch without a primary rash, starting on palms and soles, then generalised; excoriations; sometimes jaundice | Raised serum bile acids | Preterm birth, meconium, and stillbirth; stillbirth risk rises sharply with bile acids ≥ 100 µmol/L | Ursodeoxycholic acid for symptoms; obstetric monitoring and planned delivery timing |
| Pustular psoriasis of pregnancy (impetigo herpetiformis) | Usually 3rd trimester | Generalised pustular psoriasis with fever | Hypocalcaemia possible | Placental insufficiency | Systemic corticosteroids, ciclosporin; urgent obstetric care |
Pemphigoid gestationis is linked to HLA-DR3 and DR4 and, rarely, to trophoblastic tumours. Physiological skin changes in pregnancy include melasma, linea nigra, striae gravidarum, spider naevi, palmar erythema, gum hypertrophy, and telogen effluvium after delivery.
Geriatric Dermatology
Older people have more skin disease and more complications from treatment.
- Ageing skin: intrinsic ageing (thinning, loss of elasticity) combined with photoageing (wrinkles, solar elastosis, lentigines, actinic keratoses).
- Xerosis and asteatotic eczema (eczéma craquelé): cracked "crazy-paving" skin on the shins, worse in winter. Treat with regular emollients and mild topical steroids.
- Itch in older adults: often from xerosis, but always consider drugs, systemic disease, scabies (including crusted scabies in care homes), and bullous pemphigoid in its non-bullous phase.
- Skin tears: traumatic wounds in fragile skin; the ISTAP classification grades them by flap loss (type 1 no loss, type 2 partial, type 3 total). Replace the flap and avoid adhesive dressings.
- Pressure ulcers: graded by the European and US pressure injury panels as stage 1 (non-blanchable redness of intact skin), stage 2 (partial-thickness loss), stage 3 (full-thickness skin loss, fat visible), stage 4 (exposed bone, tendon, or muscle), plus unstageable (base covered by slough or eschar) and deep tissue injury. Prevention relies on repositioning, pressure-relieving surfaces, nutrition, and moisture control.
- Incontinence-associated dermatitis: irritant dermatitis from urine and faeces; protect with barrier products.
- Actinic purpura and dermatoporosis: fragile, easily bruised, atrophic forearm skin.
- Treatment choices: account for polypharmacy, kidney function, fall risk with sedating antihistamines, dexterity for topical treatment, and whether a patient can travel to phototherapy. Recombinant herpes zoster vaccine is recommended from 50 years in many European countries.
A woman at 30 weeks of her second pregnancy has intensely itchy urticarial plaques around and on the umbilicus, now with tense blisters on the abdomen and arms. What will direct immunofluorescence most likely show?
At 34 weeks of pregnancy, a woman has severe itch, worst on the palms and soles, with excoriations but no primary rash. Serum bile acids are 110 µmol/L. What is the main risk, and what drug is used for symptoms?
A 68-year-old man reports intense itch for 20 minutes after every bath or shower, with no visible rash. His haemoglobin is 190 g/L. Which test is most likely to confirm the underlying cause?
A 58-year-old woman has had dozens of very itchy, hyperkeratotic nodules on her arms and legs for 2 years, despite potent topical steroids and phototherapy. Which systemic treatment is approved in the EU for this condition?