This document outlines the process for diagnosing skin diseases. It discusses taking a thorough history including presenting complaints, symptoms, duration, site of involvement, and evolution of lesions. The examination evaluates skin lesions based on morphology, distribution, and configuration. Important investigations are also described such as potassium hydroxide mount to check for fungal infections, Tzanck smear to examine skin blisters cytologically, and various serological tests. A thorough history, physical exam, and selection of appropriate diagnostic tests are essential for accurately diagnosing skin conditions.

1. Diagnosis of
Skin Diseases
DR SUBODH KUMAR SHAH

2. History Taking
Presenting Complaints
 Subjective symptoms: Which cannot be seen by physician
and include symptoms like itching, pain, and paresthesia
 Objective symptoms: Which can be seen by a doctor and
include symptoms like rash, ulcers, hair fall (or growth),
changes in nails, etc.

3. For each symptom, the following questions should be asked:
 Duration: Is the problem acute or chronic? If chronic,
about relapses and remissions.
 Site of first involvement: And spread.
 Evolution: Of lesions.
 Diurnal variation: , itching is generally
more severe at night because the patient’s mind is not
diverted. But in sun-induced , the itching is
logically worse during the day.

4. Past History
 Any medication received recently , including regular or intermittent
selfmedication.
 Any past illness (medical, surgical) and therapy,
thereof, are important in drug eruptions.
 History of medical disorders like diabetes,
hypertension, tuberculosis, seizures is relevant.
 manifestation of the disease or could be an adverse effect of the drug used
to treat the disease.
 Past exposure to Mycobacterium tuberculosis
is important, when cutaneous tuberculosis is suspected.

5. Family History
 Genetic disorders like ichthyosis, neurofibromatosis
and epidermolysis bullosa.
 Infections and infestations, e.g., scabies, pediculosis.
 Families who are exposed to similar environmental
influences may also develop same problems e.g.,arsenical keratoses.

6. Examination
Skin lesions have to be described in three terms:
 Morphology
 Distribution.
 Configuration.

7. Investigations
 Magnifying Lens
A magnifying lens amplifies subtle changes in the skin. A 5× or 10× convex
lens produces optimum magnification.
 Wood’s Lamp
Wood’s lamp is a device which emits ultraviolet rays (wavelength, 360 nm).

8. Some Important Investigations
Potassium Hydroxide Mount : if a fungal infection is suspected.
 Skin sample is put on a glass slide and an aqueous solution of 20%
potassium hydroxide is added before applying the cover slip.
 After 20–30 min (60–90 min in case of nail clippings) mount is examined
under microscope with condenser lens lowered to enhance contrast.
 Fungal hyphae/pseudohyphae/spores are looked for
hyphae appear as septate tube-like structures

9. Tzanck Smear
 Is cytological examination of skin blisters.

10. Intradermal Tests
 Tuberculin test.
 Lepromin test.
Serological Tests
 Serological tests for syphilis.
 Serological tests for HIV infection.
 Serological tests for collagen vascular disorders,e.g., antinuclear
 Serological tests in bullous disorders, e.g., desmoglein levels in
pemphigus.

11. Thank you