Skin diagnostic tests are indicated when the cause of a skin lesion or disease is not obvious from history and physical examination alone. These Skin diagnostic tests include

  • Patch testing
  • Biopsy
  • Scrapings
  • Examination by Wood light
  • Tzanck testing
  • Diascopy

Patch testing

Patch tests are used to help diagnose allergic skin reactions. Allergens (substances a person may be allergic to) are placed on the skin on the back with adhesive patches and left for a period of time. Then the skin is examined for any reaction.


There are several types of skin biopsy:

  • In a punch biopsy, a tube hole (usually 4 mm in diameter) is inserted into a deep or subcutaneous dermal tissue to obtain a sample that is cut from its base.
  • Shaving can be done with a scalpel or a razor blade for superficial lesions. Bleeding is controlled by aluminum chloride solution or electrophoresis; Large incisions are closed with sutures.
  • Wedge excision can be performed with a scalpel for larger or deeper biopsies. Pigmented lesions are often excised for depth histological evaluation; If the final diagnosis is too superficial, it may be impossible. Diagnosis and simultaneous treatment of most small tumors can often be achieved by complete resection that includes small borders of normal skin.


Skin scales help diagnose fungal infections and scabies. If a fungal infection or scab is suspected, the doctor may perform a skin scraping. During this test, a doctor scrapes some material from the skin, such as a scale, and examines it under a microscope. Sometimes chemicals or special stains are applied to the material.

Wood light

Wood light (dark light) can help clinicians in diagnosing and deciding the degree of injuries (for instance, the fringes of pigmented sores before circumcision). It can help distinguish between hypopigmentation and hypopigmentation (this does not happen with depigmentation from ivory white radiant vitiligo and hypopigmented lesions). Erythrasma glows in a distinctive bright red-orange color. Tinea capitis induced by Microsporum canis and M. audouinii fluoresces in a light green color. (Note: most tinea capitis in the United States is caused by Trichophyton species, which do not fluoresce.) The greenish glow may be the first evidence of cutaneous Pseudomonas infection (for example, in burns).

Tzanck testing

The Tzanc test can be used to diagnose viral diseases, such as herpes simplex and shingles, and is performed when healthy vesicles are active. The Tzanck test cannot distinguish between a herpes simplex infection and a shingles infection. Healthy blisters are the preferred lesion for examination. The roof of the blister is removed with a sharp blade, and the unroofed base of the vesicle is scraped with a # 15. scalpel blade. The cuttings are transferred to a slide and stained with Wright's stain or Jamesa stain. Multinucleated goliath cells are an indication of herpes disease.


A developmental endoscopy is performed so that a doctor can observe the color changes that occur when pressure is applied to the skin. During this test, the doctor presses a microscope slide against the lesion to see if it is blanching (blanching) or changing color. Certain types of pests bleach, while others do not. Some skin lesions (such as those caused by sarcoidosis) turn yellowish-brown upon this test.

Skin diagnostic tests are also include:


Culture is a test performed to identify the microorganism (bacteria, fungi, or virus) that is causing the infection. Skin (surface scrapings, biopsies, pus bumps and pus contents), hair or nails can be transplanted to detect bacteria, fungi, or viruses.

Dermascopy (a non-obtrusive strategy utilizing a handheld gadget that empowers dermatologists to more readily observe the sore), confocal imaging, and tape expulsion to take a gander at hereditary material are other analytic procedures that will be utilized later on.

Blood tests

These require a small blood sample, which is usually drawn through a needle in the arm. One of these tests looks for high levels of eosinophils, which are cells in the blood that are part of an immune reaction. Another is looking for high levels of a molecule called IgE antibody. Levels of this blood are elevated in people with atopic diseases, including eczema. More useful are the allergen-specific IgE tests, which measure levels of the antibody, each linked to different allergens. Note: IgG food antibody is not a useful test for determining a food allergy.

Allergy skin testing

Skin prick tests may be done for common foods or inhaled allergens to show sensitivity or lack of sensitivity to specific allergens due to eczema.

Imaging tests

Most skin cancers, especially basal cell carcinoma, which is the most common form of skin cancer, remain localized and have not spread to distant organs. Melanoma and Merkel cell carcinoma are more likely to spread. In these cases, one of several medical imaging procedures may be used to determine whether cancer cells have spread to internal organs and bones. Include imaging procedures:

  • CT scan
  • X-ray
  • MRI

These imaging procedures are non-invasive and painless. If it reveals suspicious spots or metastases, a more invasive biopsy may be required.

A Dermatologist is a medical specialist who deals with the prevention, diagnosis, treatment and management of diseases and problems related to skin, hair & nails. Find the best Dermatologist in Hyderabad Book doctor appointment online with top Dermatologist, view consultation fees, reviews, Op timings, hospital address Skedoc.

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The skin is an incredible organ. It's your first line of defense against illness, and it protects your other organs, warms and cools you, and sends messages about how healthy you are on the inside. Dermatologists are professional doctors and skin surgeons with unique skills and experience to provide the best care for the organ that cares for you.

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