Approach to pruritus without apparent rash

Introduction

Approach to pruritus without apparent rash

Pruritus is an unpleasant irritating sensation that urges the patient to scratch. History taking in a patient with pruritus is the first step to solve the puzzle. Chronic pruritus is usually disturbing the patients and badly affects the quality of their lives. Here, we are going to discuss an approach to pruritus in patients without specific apparent skin rash. In other words, there is no primary skin lesions but of course secondary skin lesions may be present like (lichenification, excoriation, hyperpigmentation and erosions ). The aim of history taking is to get our hands on the cause of the pruritus. Treatment of the underlying cause may help these pateints to continue their normal lives again. On the other hand, for some patients, the underlying condition is not evident and this is what can be called chronic pruritus of unknown origin. Revaluation of chronic pruritus patients is essential becuase some skin diseases initially have no evident skin findings but the skin lesions may be detetected later upon the follow up visits.

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Chronic, progressive, generalized pruritus without primary skin lesions should raise

suspicion of an underlying systemic disease.

Bolongnia 2017

Causes of pruritus without apparent primary skin lesions

• Xerosis
  • It is more common in elderly patients, it is usally evident on the legs.
• Drug induced pruritus
  • Antibiotics.
  • Cardiovascular drugs.
  • Antimalarial drugs.
  • Oral contraceptive pills.
  • Others : Rituximab, Imatinib, Infliximab, Hydroxyethyl starch, targeted cancer therapies.
• Systemic diseases
  • Diabetes : Pruritus may be due skin dryness, daibetic neuropathy or associated skin infections.
  • Thyroid diseases : Generalised pruritus may be the presenting complain of hyperthyroidism (Grave`s disease)
  • Renal diseases : Uremic pruritus is common in end stage renal disease patients. Patients on dialysis usually complains of severe generalised pruritus.
  • HIV infection.
  • Hematological
    • Iron defeciency anemia.
    • Polycythemia vera : Patients complain of itching minutes after contact with water (aquagenic pruritus), patients may complain aquagenic pruritus years before the diagnosis.
  • Hepatic disease : Palmoplantar pruritus that extends to be generalised may point to a on the following conditions
    • Primary biliary cholangitis.
    • Intrahepatic cholestasis of pregnancy.
    • Sclerosing cholangitis.
    • Viral hepatitis.
    • Drug-induced cholestasis.
    • Obstructive jaundice.

• Skin diseases
  • Lichen simplex chronicus : localised lichenified plaques of the skin.
  • Atopic dermatitis : chronic pruritus is one of the main criteria of atopic patients.
  • Paraneoplastic
    • Eruptive seborrheic keratosis (Lesser Trelat sign) .
    • Malignant acanthosis nigricans.
    • Dermatomyositis.
    • Erythroderma.
  • Parasitic infections
    • Scabies.
    • Pediculosis.
• Tumors
  • Hodgkin lymphoma : chronic pruritus usually preceds other signs of the malignancy by weeks, months or years.
  • Mycosis fungoides : Pruritus may precede the appearance of the full clinical picture.
  • Leukemias :  chronic lymphocytic leukemia.
  • Plasma cell dyscrasias.
  • Gastric carcinoid tumors.
  • Cerebral Tumour.
• Neurological pruritus
  • Brachioradial pruritus.
  • Notalgia paresthetica.
  • Multiple sclerosis.
  • Brain tumor.
  • Brain infarction.
  • Postherpetic neuralgia.
• Psychiatric or psychosomatic diseases
  • Neurotic excoriations.
  • Delusions of parasitosis.
  • Somatoform disorders : a different group of psychiatric disorders that are characterized by unexplained physical symptoms.
  • Depression.
  • Affective disorders.
  • Hallucinosis.
  • Obsessive and compulsory disorders.
  • Schizophrenia.
  • Eating disorders.

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History taking in a patient with pruritus without rash

• The onset and duration of pruritus.
  • Chronic pruritus usually persists for at least 6 weeks.
• It is localised or generalised. unilateral or bilateral.
  • Localised pruritus may alert you to neuropathic itching, specially, if it is dermatomal or the patients also complains of burning sensation or abnormal sensation in that part of the skin.
  • Examples of neuropathic itching may include:
    • Diabetes : Ask about polydipsia and polyuria.
    • Nerve entrapment including brachioradial pruritus.
    • Notalgia parasthetica.
    • Postherpetic itching.
• How severe is it?
  • mild, moderate or severe.
  • It has any effect on quality of life and sleep or not?
• How often do you feel it?
  • Time course: intermittent, continuous, cyclical, nocturnal.
• Ask about temperature intolerance : it may point to thyroid problem.
• Is it related to physical excercise?
  • Cholinergic pruritus may be considered.
• Is it related to bathing
  • Aquagenic pruritus should be considered.
• Seasonal pruritus in winter may point to xerosis cutis that is more common in elderly.
• Any allergies to drugs, food or contact substances?
• Family or personal history of atopy?
• Is there any other affected family member or close contacts?
  • Scabies may presents with generalised nocturnal itching in a group of pateints living at the same place.
  • Insect bite reactions may als affect family members.
• What about fever, unexplained weight loss and night sweats?
  • To exclude clinical signs of malignancy.
• Assessment of the itching severity using the visual analogue scale.
• What make it better and what make it worse ? Ask about any triggering factors or ameliorating factors
  • Heat, cold, shower, rubbing, scratching, etc.
• Ask about any relation between drug intake, medical illness or previous surgeries and pruritus.
• Skin care products, bathing habits and contact with irritants.
• Exclude drug induced pruritus
  • A long list of drugs can induce drug induced pruritus.
  • Drugs like chemotherapeutic agents, anti diabetes drugs, anti hypertensive drugs, antibiotics and analgesics may be implicated in such condition.
  • Discontinuation of the suspected drug may not be easy in patients with chronic diseases.
  • Withdrawl of the causative drug doesn`t mean that pruritus will improve immediately, it may take weeks or months before pruritus settles down.
• Ask about psychogenic stress factors?
  • Did it start after a stressful life event?
• History of any systemic disease?
  • Renal, hepatic, blood, thyroid, etc..
• Do you have any pets at home, any contact with animals?
• What is the impact of the condition on sleeping and quality of life?
• Ask about previous skin diseases, blood transfusion ?
• Travel history.
• Sexual history.
• Psychiatric and substance abuse history.
• Inquire about pregnancy in child bearing females.
  • Exclude dry skin as a common cause of itching in pregnancy.
  • Dermatoses of pregnancy should be suspected, e.g Pruritic urticarial papules and plaques of pregnancy (PUPPP), intrahepatic cholestasis of pregnancy (ICP), pemphigoid gestationis (PG), and atopic eruption of pregnancy.
• What were the previous medications that have been used to treat the condition? and whether they were successful or not?
• What is the patient`s own theory about the cause of the pruritus?

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Examination

• Complete skin examination.
  • Skin, hair, scalp, nails, mucous memebranes and anogenital region.
  • Try to detect any primary lesions.
  • Xerosis.
• Lymph node examination.
  • Cervical, supraclavicular, axillary, inguinal.
• Liver, spleen and kidney palpation

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Investigations for pruritus without rash

Main investigations

• Complete blood count with differential
  • to evaluate for evidence of malignancy, myeloproliferative disease, or iron deficiency.
• Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP)
• Serum bilirubin, transaminases, and alkaline phosphatase
  • to evaluate for evidence of liver disease.
• Thyroid-stimulating hormone
  • to evaluate for evidence of a thyroid disorder.
• Blood urea nitrogen and creatinine
  • to evaluate for renal disease.
• Chest radiograph
  • to evaluate for evidence of adenopathy.
• Fasting glucose.

Complementary investigations

In the light of clinical picture, history and examination, another tests may be required

• Stool analysis for ova and parasites.
• Stool occult blood if age more than 40.
• Hepatitis B or C, HIV tests.
• Serum protein electrophoresis, and immuno-electrophoresis.
• CT scan of the chest and abdomen
  • May be justifiable to help rule out lymphoma.
• Skin biopsy
  • Skin biopsy is useful to exclude clinically unapparent cutaneous mastocytosis, bullous pemphigoid, or incipient mycosis fungoides.

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Points to remember from Approach to pruritus without apparent rash

• Try to figure out if there are any primary skin lesions. the skin is inflammed or not? Dermoscopy may be helpful. Itching may be due a skin disease (Urticaria- Atopic dermatitis – Scabies- etc)
• If the skin is appearing normal with no primary lesions ( secondary skin lesions may be present), and the patient has chronic pruritus, one of the following causes should be suspected.
  • Pruritus of systemic disease, infection or malignancy.
  • Neuropathic pruritus.
  • Psychiatric or psychosomatic diseases.

• A detailed history and complete skin examination have to be taken to differntiate between different types of pruritus.
• In th light of history and examination, investigations including skin biopsy may be required to reach a diagnosis.
• Put in mind, xerosis is the most common cause of itching.
• If no underlying cause is defined, diagnosis of chonic pruritus of unknown origin(CPUO) may be made.
• Pruritus may precede the diagnosis of the underlying disease by years.
• Pruritus may be due to overlap betweem different diseases.
• Mangement of chonic pruritus may inquire referal to the following
  • Internal medicine specialist.
  • Neurlogist.
  • Psychiatrist.
  • Onchologist.

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