Diagnosis of skin itching

In the differential diagnosis of pruritus, it should be borne in mind that mastocytosis, pemphigoid or herpetiform dermatosis of Dühring can initially appear in pruritus on clinically healthy skin, and seborrhea in skin patients hardly gives in to objectification.

In those cases where it is impossible to relate the itch to any dermatological disease, other causes should be sought. Generalized itching, in the absence of a primary skin disease, can be an important sign of an internal disease: uremic pruritus (kidney disease); Cholestatic itching (mechanical jaundice, cholestatic hepatitis, primary biliary cirrhosis); endocrinopathic itching (diabetes mellitus, pruritus); paraneoplastic itching (Hodgkin's disease, visceral carcinoma); neurogenic pruritus (neurological diseases); psychogenic itching (mental illness); drug itching (taking some medications).

When examining the patient's body with complaints of itching, it should further distinguish between itching and skin manifestations and without them. However, before concluding that there are no cutaneous manifestations, the most thorough examination of the patient's body, from the skin of the feet to the scalp, including the nasal cavity and the external auditory meatus, the areas of the anus, the scrotum and the vulva, as well as the nails and the interdigital space, is necessary. And only when all these areas of the body are unchanged, we are talking about itching without skin manifestations. Next, you should pay attention to whether there is an increase in lymph nodes, spleen, exophthalmus or signs of diabetes and, of course, xerosis.

A true assessment of pruritus is the most difficult task, requiring careful examination of the patient. Detailed collection of anamnesis about the time of onset, course and intensity of pruritus is mandatory. It should always be interviewed about the following characteristics of the itch: generalized - localized; continuous - paroxysmal; progredient - fading; depending on temperature, situation, time of day.

It should be determined whether the itch provokes or strengthens it such factors as water, heat, dryness or humidity, physical stress, cooling of the skin. Always inquire about staying in the tropics, contacting animals, taking medicines, and about eating habits and favorite treats (dyes, additives, preservatives). Careful anamnesis regarding atopy, as well as profession, social status, up to sexual life, should also be present. Even without examining the patient's skin, the simple question of whether other family members or partners suffer from itching can already indicate an infectious genesis. The itching, which calms down with falling asleep, does not lead to sleep disturbance and increases markedly in intensity upon rising, indicates a strain that can be mentally caused. Itching, which does not allow patients to fall asleep, or because of which they wake up at night, is more likely caused by a systemic disease. Various skin diseases are characterized by continuous itching, such as atopic dermatitis, in which only the sleep that comes from exhaustion "covers up" attacks of itching. Night sweats and subfebrile temperatures associated with pruritus are almost pathognomonic for Hodgkin's disease and are often provoked by an evening drink of alcohol. These few examples sharpen the doctor's attention to the correct formulation of questions in the collection of anamnesis in a patient with itching, especially without typical skin manifestations.

Anamnesis of the disease with skin itching

• The beginning (sharp, gradual)
• The flow (continuous, intermittent)
• Character (stitching, burning)
• Duration (days, months)
• Time (cyclical, during the day, at night)
• Degree of suffering (impact on everyday life)
• Localization (generalized, limited)
• The provoking factors (water, temperature, friction)
• Reception of medicines
• Environmental factors (profession, hygiene, pets)
• Psychotraumatic situations in the recent past
• Allergies, atopy
• Anamnesis of trips (places of business trips, rest)
• Sexual history
• Prior therapy

Itching is rarely continuous. Sometimes it depends on the temperature change, for example, when entering a warm room after a stay in the cold air. Itching may occur in the form of crisises during the day, but more often it intensifies at night. With some dermatoses (for example, a simple sub-strand of prurigo), limited inflammation of the skin is combed until the blood runs, only then the itching stops. Often with eczema, itching is worse with combs and recedes when the patient is depleted after scratching. An itch is known, absent during the day and reviving at night: a typical anamnesis for scabies.

The definition of an itch of an unclear genesis is a big problem of a differential diagnosis. It is at a later age that one should think about the simultaneous presence of several diseases that can give rise to itching (age sebostasis in combination with hormonal disorders, malnutrition or malignant tumors). In practice, it is advisable to conduct trial local treatment with indigestible fat-based ointments. Sometimes it is difficult to distinguish the secondary effects of pruritus on the skin from primary dermatoses. The effect of prolonged itching on the patient's psyche, causing prolonged insomnia or neurasthenia, should not lead to an erroneous diagnosis of a psychiatric illness. It is important to establish whether the patient has lymphadenopathy or hepatosplenomegaly, since lymphomas can be accompanied by itching. Itching without rashes on the skin sometimes serves as an indicator of HIV infection, often accompanied by a candidiasis of the oral cavity and lymphadenopathy. Sometimes, when examining the skin, erroneous rashes are seen as the cause of the itching, although in fact they represent its result.

The following aids will help diagnose the itching of the skin: a magnifying glass (possibly a microscope), a glass ruler, a pair of small forceps, a tool with a blunt end (spatula), a probe, a small anatomical tweezers. In addition to a visual examination, the doctor will need his sense of touch (palpation, general examination), and in some cases - his nail. Before the clinical examination, the patient's history should be collected in as much detail as possible. For the examination, the patient is asked to completely undress. In the case of itching states, it is important to check every centimeter of the patient's skin, even if he denies the presence of any visible skin lesions.

In addition to collecting anamnesis and physical examination, a purposeful individual examination program should be carried out, since pruritus can precede the manifestation of a systemic disease. Patients should be closely monitored in the future.

A minimal laboratory program to determine the possible causes of pruritus in the absence of typical manifestations of any dermatosis should include, in addition to determining the parameters of inflammation (ESR and C-reactive protein), a differential blood test with counting the number of eosinophils and platelets, transaminase with alkaline phosphatase and bilirubin, and also transferrin and iron, urea and creatinine, uric acid and sugar, calcium and phosphate. The study of hormones, thyroid and parathyroid glands, the determination of the overall IgE level in connection with the evidence of intestinal parasitosis completes the program.

Patient examination plan with skin pruritus

• General examination (temperature, sweating, fatigue, weight loss)
• Skin (pigmentation, dryness, icterism, traces of excoriation)
• Nails (change in color, dystrophy, onycholi-zis)
• Eyes (exophthalmos, discoloration of sclera)
• Endocrine system (tremor, violation of thermoregulation, polydipsia, polyuria)
• The blood system (anemia, bleeding, lymph-drainage)
• Gastrointestinal tract (nausea, vomiting, stool, incontinence of the bladder and color)
• Urogenital system (urine color, incontinence, menstruation, pregnancy)
• Nervous system (headaches, paresthesia, visual disorders)
• Mental status (mood, sleep disturbances, hallucinations, delusions)

Patient examination plan with skin pruritus

• General blood analysis
• Biochemical blood test (alkaline phosphatase, bilirubin, urea, creatinine)
• T4 (thyroxine), TSH (thyroxine-binding globulin)
• Blood test for iron, ferritin
• A blood test for total protein and protein fractions (a1, a2, beta, gamma)
• HIV serology (ELISA-HIV)
• Fecal occult blood test
• Analysis of feces for eggs of helminths
• Urine analysis (5-hydroxyindoleacetic acid, 17-ketosteroids)
• Skin biopsy (histology, immunofluorescence, electron microscopy)
• X-ray and ultrasound
• Endoscopy (fibroesophagogastroduodenoscopy, sigmoidoscopy, colonoscopy, laparoscopy)

If you suspect a pruritus associated with paraneoplasia, you should conduct appropriate studies using tumor markers, as well as minimally invasive studies such as chest X-ray and ultrasound.

Sometimes it helps to determine the level of histamine, serotonin and tryptase (diffuse mastocytosis, nephropathy, hepatopathy). With lichen-venous lesions, biopsy will eliminate granulomatous dermatoses. Studies associated with infections should always be carried out purposefully.

[1], [2], [3], [4], [5], [6]