Most impoant in the diagnosis of leprosy is
Hypopigmented anesthetic patch is the most impoant feature ofvleprosy Cardinal signs of leprosy 1. Anesthetic patches or anesthesia: This may be a suggestive skin lesion(s) (hypopigmented or erythematous) with sensory impairment or loss, or else there may be just an area of sensory deficit, more often in the distribution of a nerve trunk or limited to the distal pas of extremities. There may be complete loss or diminished sensations of touch, pain, and/or temperature. 2. Thickened peripheral nerves or local cutaneous nerves: Nerve affection is the major feature of leprosy. Most often there is a perceptible thickening of the regional nerve trunk(s), sensory and/or mixed. In some cases a proximally located nerve can be observed. 3. Acid-fast bacilli: Finding of acid-fast bacilli (M. leprae) on slit skin smears in lepromatous or borderline leprosy is diagnostic. In tuberculoid or indeterminate leprosy, a skin biopsy may be required to demonstrate AFB. For the diagnosis of leprosy, at least two of the three cardinal signs or demonstration of acid-fast bacilli is essential. The above cardinal signs are present in a classical case, but in cases of early leprosy only one of the first two cardinal signs may be present, and leads one to suspect leprosy. iadvl textbook of dermatology page 2055
Evidence of neural involvement
Hypopigmented patch
Slit skin smears
Positive lepromin test
Bacterial infections