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Hypertensive driven mad by itching

Dr Tanvir Jamil discusses a tricky presentation

Dr Tanvir Jamil discusses a tricky presentation

Case history

Dorothy is a 65-year-old hypertensive patient. You see her for a routine six-monthly blood pressure check. All is fine but as she leaves she asks you for sleeping tablets. She can't sleep a wink for this 'blessed itching' that she has endured for over six months.

Itching is the commonest dermatological symptom with many causes. Is there a logical way to divide them?

Think skin, systemic, medication and others:

  • Skin: parasites (scabies, flea bites), eczema, urticaria, dermatitis herpetiformis, lichen sclerosis, lichen planus, lichen simplex chronicus
  • Systemic: diabetes, thyroid disease, iron deficiency anaemia, liver disease, chronic renal failure, neoplasm (Hodgkin's, leukaemia, non-Hodgkin's, carcinomatosis especially bronchial, solid tumours eg pancreatic, stomach, polycythemia rubra vera
  • Medications: antidepressants, aspirin, CNS stimulants, oestrogens, opiates
  • Others: pregnancy, postmenopausal, winter itch (xerosis), psychogenic

Skin changes mean skin disease ­ true or false?

Often but not always. Skin changes are not uncommon in people with chronic itching. Persistent rubbing and scratching can cause papules, plaques or nodules. These skin changes occur commonly around the scalp, extremities and the back of the neck.

Lichenification can also occur from persistent itching, causing thickening of the skin. It's important to be aware of the fact that these changes are often a consequence and not a cause of the itch.

Are there any clues in Dorothy's history and examination that could point to a diagnosis?

The symptoms of hyper or hypothyroidism are well documented and it is worth asking about these specifically. Look for the typical signs on examination. Itching associated with fever, night sweats and weight loss may point to lymphoma. Examination may reveal splenomegaly and lymphadenopathy.

Burning in the hands or feet, especially if the patient has had a history of venous or arterial thrombosis, may indicate polycth-aemia rubra vera. Look for facial plethora. Lastly think about a psychogenic cause if your patient complains of bugs crawling under her skin.

Which investigations should I be thinking about?

You sound like you're still in hospital mode. Remember in general practice we have time to monitor our patients and can wait things out occasionally. If there are no clues that point to a clinical diagnosis, it is appropriate to treat symptomatically for two weeks with oral antihistamines, moisturisers and general advice such as less frequent bathing, keeping cool, 'pat' drying and avoiding irritant fibres such as wool.

If treatment is successful and itching does not recur after stopping treatment, no further investigation is necessary. If itching isn't helped with therapy or restarts after treatment stops it's time to investigate further.

Dorothy is still itching two weeks later. Should I investigate now?

Good idea. The tests you should be thinking about include:

  • urinalysis ­ diabetes
  • FBC, ferritin levels ­ iron deficiency anaemia, blood dyscrasia
  • ESR ­ raised in lymphoma or other malignancy
  • LFTs ­ liver disease
  • U&Es ­ renal failure
  • Thyroid function tests ­ hyper/hypothyroidism
  • Blood glucose ­ diabetes

How many people with generalised itching have a malignancy?

Fewer than 1 per cent of referred patients are found to have a malignancy. The two main considerations are non-Hodgkin's and Hodgkin's lymphoma. Generalised pruritus occurs in less than 10 per cent of patients with non-Hodgkin's but about 40 per cent get the systemic complaints already mentioned above. Sixty-six per cent will have peripheral lymphadenopathy.

Many more patients seem to have generalised pruritus Hodgkin's ­ although it usually manifests itself after the diagnosis has been made. In a few patients, however, it may occur early on, sometimes preceding a diagnosis by months or even years.

Mediastinal lymph nodes are involved in about 60 per cent of patients and you might want to think about a chest X-ray, even in the absence of other symptoms. Generalised itching is the second most common skin manifestation of leukaemia after purpura. Typically it appears late in the disease but may appear early. You may need to request examination of the peripheral blood film. Of the visceral malignancies, the commonest causes of generalised itching are pancreatic or stomach cancer.

I've heard that 'winter itch' is very common in older patients?

Also know as 'xerosis', this is common in cooler climates and should be suspected when itching starts in the winter months. It appears to be caused by excessive drying of the skin from central heating. Treatment is rehydration and liberal moisturising.

Are there any other non-serious causes of generalised itching?

Scabies ­ some of the lesions may be very subtle but the classic history is that other members of the family have similar symptoms. Physical examination occasionally reveals burrows, although how many GPs actually have time to dig the mite out and look at it under the microscope is uncertain.

Working with fibreglass can cause an irritant dermatitis with occasional fibreglass particles seen on skin scrapings.

Aquagenic pruritis is associated with itching after a bath or a shower. The temperature of the water does not matter. There are no skin manifestations and the symptoms usually abate within the hour. There is often a positive family history.

Let's suppose that all investigations are normal, the patient looks well and there are no skin changes. Now what do I do?

Have you considered psychogenic pruritus? This is a diagnosis of exclusion but may sometimes need a psychiatric referral. Anxiety and depression can cause generalised itching and a feeling of something 'crawling under the skin.'

If a psychiatric cause is unlikely your only option is to treat symptomatically and review the patient regularly, looking for any changes in the history and signs of underlying disease.

Key points

  • Itching is the commonest dermatological symptom
  • Treat symptomatically for two weeks if the diagnosis is not obvious
  • Fewer than 1% of referred patients are found to have a malignancy

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