Chronic itching of unknown origin.

What is it chronic pruritus of unknown origin?

Chronic pruritus of unknown origin is defined as an itch that lasts for more than six weeks in the absence of a known cause. [1]. Also called chronic. idiopathic itching and generalized pruritus of unknown origin.

Who gets chronic pruritus of unknown origin?

There are no detailed studies on the predominance chronic pruritus of unknown origin currently exists. There is a higher prevalence with older age [2].

What causes chronic pruritus of unknown origin?

At present, the Pathogenesis chronic pruritus of unknown origin remains unknown [1].

What are the clinical features of chronic pruritus of unknown origin?

In chronic itching of unknown origin, itching may be located or generalized. The skin may appear normal or it may be erythematousrough or bumpy Repeated scratching can cause secondary skin changes, such as lichenification (thickening, hyperpigmentation and improved skin tags), bleeding or a localized secondary bacterial infection [3].

What are the complications of chronic pruritus of unknown origin?

When chronic itching is accompanied by severe scratching, complications can arise. Changes in the skin include:

• A localized thickening license plate (Simple lichen, a type of eczema)
• Nodular prurigo, characterized by pruritus nodules 10 to 20 mm in diameter

• Impetigo due to secondary bacterial infection after scratching.

Insomnia due to itching can greatly affect quality of life and worsen comorbid conditions, including depression and anxiety. [3].

How is chronic pruritus of unknown origin diagnosed?

Chronic pruritus of unknown origin is predominantly a diagnosis of exclusion of primary underlying dermatological and medical disorders.

Patients with chronic pruritus of unknown origin may have some positive results, although these findings are not specific. These include eosinophiliawarm immunoglobulin (Ig) -E elevation (up to 1000 IU / mL), or dermal hypersensitivity. Eosinophils can be seen in the dermis on the skin biopsy [1].

Which is the differential diagnosis for chronic pruritus of unknown origin?

Chronic itching can be associated with several underlying conditions. The International Forum for the Study of Itching developed a classification system that divides chronic pruritus into six main groups based on its underlying cause: dermatological, systemicneurological psychiatric, multifactorialor of unknown origin [4].

Dermatological causes of pruritus with visible signs include:

• Inflammatory disease
  • Atopic dermatitis
  • Contact dermatitis
  • Lichen planus
  • Psoriasis
  • Spontaneous Chronicle urticaria
  • Bullous pemphigoid
• Infectious disease
  • Herpes Simplex
  • Scabies
  • Molluscum contagiosum
  • Candida infection
• Neoplasm
  • Cutaneous T cell lymphoma

  • Sézary syndrome.

Systemic causes of itching include:

• Endocrine disease
  • Diabetes mellitus type 2
  • Hypothyroidism
  • Hyperthyroidism
• Cholestatic pruritus
  • Primary biliary cirrhosis
  • Intrahepatic cholestasis of pregnancy

• Drug induced itching

  • Chloroquine
  • Hydroxyethyl starch
  • Others
• Uremic itching
  • Final stage renal disease
  • Hemodialysis associated or not
• Hematological disease
  • Lack of iron
  • Polycythemia will see
• Neoplasm
  • Hodgkin lymphoma
  • A solid tumor (see paraneoplastic pruritus)
• Systemic infection

  • Human immunodeficiency virus (HIV) infection

  • Chikungunya fever
  • Hepatitis C

  • Onchocerciasis with or without onchocercal skin disease

  • Strongyloidiasis with or without larva currens or urticaria

  • Possible: human polyomavirus, Helicobacter pylori, toxocariasis

Neurological Diseases that can lead to itching include:

• Compression syndromes (neuropathic disorders)
  • Notalgia paraesthetica
  • Paraesthetic meralgia
  • Brachioradial itch
• Degenerative terms
  • Race
  • Small fiber neuropathy (eg, due to diabetes mellitus).

Psychiatric illnesses that can lead to itching include:

• Psychosomatic pruritus
  • Somatoform pruritus
• Delusional disorders
  • Delusional parasitosis
  • Compulsive harvest.

The multifactorial reasons for chronic pruritus of unknown origin are a combination of two or more underlying conditions.

Pruritus of unknown origin is diagnosed when the conditions described above have not been detected.

What methods can help diagnose chronic pruritus of unknown origin?

Factors in the patient's history that may aid in the diagnosis of chronic pruritus of unknown origin include:

• Timing, location and duration of itching.
• Medications and comorbidities.
• Environment and exposures (eg, Sarna, irritating contact dermatitis).

Main laboratory tests

The main lab tests that can be done to diagnose chronic pruritus include:

• Complete blood count (CBC) with differential
• Liver function tests
• Kidney function tests.
• Thyroid function tests
• In an older individual, indirect immunofluorescence for the skin autoantibodies.

Optional tests

Skin biopsy is recommended in any patient who has primary skin without scratching injury in an itchy site. Biopsy of a excoriation it will show a minor change and is not useful for diagnosis. You should undergo a histopathological examination and direct immunofluorescence.

Yes malignancy a possible cause is considered, refer for detection of malignancy. If itching is present for less than a year, evaluate for Hodgkin lymphoma and liver tumor, especially if symptoms B are also present like fever and discomfort [2].

If a neurologic cause is suspected, refer to a neurologic exam.

What is the treatment for chronic pruritus of unknown origin?

Lifestyle modifications to treat chronic pruritus of unknown origin should include:

• Avoid heat, ice packs, frequent bathing, alcohol, spicy food, and contact with irritants such as tea tree oil and chamomile.
• Bathe in lukewarm water with a mild, non-alkaline, soap-free cleanser.
• Consider relaxation training and psychosocial education for anxiety patients [5].

Regardless of the source of the itch, empirical therapies can alleviate symptoms.

• Moisturizing emollients
• Antipruritic creams that include menthol or polidocanol [2].

If the cause is not found, once the diagnosis of chronic pruritus is complete, treatment with current and systemic agents are recommended. Often these agents are given over a trial period to determine if they will provide any relief from the itch.

Topical agents

Short-term treatment with topical steroids may be indicated for secondary eczema and to break the itch-scratch cycle. Long-term use of topical steroids is not recommended, as topical corticosteroids lead to the skin. atrophy and they are not effective for itching.

Topical calcineurin inhibitors, such as tacrolimus ointment and pimecrolimus cream, to have anti-inflammatory properties and exert their effects on the skin nerves to suppress itching.

Systemic agents

Phototherapy has an antipruritic effect in several itchy skin conditions, including atopic dermatitis, psoriasis, cutaneous T-cell lymphoma, uremic pruritus, and neuropathic syndromes. It can also be effective in chronic pruritus of unknown origin.

Cyclosporine is one of the immunosuppressive drugs and can control inflammatory skin disease. It is usually ineffective in chronic pruritus of unknown origin.

Gabapentinoids, such as pregabalin and gabapentin, are used for pruritic neuropathic syndromes.

Antidepressants, such as selective serotonin reuptake inhibitors (SSRIs), can control somatoform and paraneoplastic itching. Mirtazapine has been shown to be helpful in chronic spontaneous urticaria and chronic pruritus of unknown origin.

Novel treatments

New agents under investigation for the treatment of chronic pruritus include:

• Drugs that act on opioid receptors.
• Neurokinin-1 receiver antagonists
• Janus kinase inhibitors
• Monoclonal antibodies against cytokines how interleukin (IL) -4, IL-13, IL-31.

What is the result of chronic pruritus of unknown origin?

Although chronic pruritus of unknown origin is not life threatening, it has a significant impact on the quality of life of the patient. It often persists for long periods or indefinitely.