How is the diagnosis of leprosy usually made?
| | Fig. 29.2 Nerve enlargement. Palpable or visually enlarged nerves may be a sign of leprosy. | The diagnosis of leprosy is usually made by demonstrating cutaneous anesthesia, by finding enlarged superficial nerves, and by demonstrating leprosy bacilli in the skin. - Cutaneous anesthesia is best diagnosed by using a wisp of cotton to demonstrate loss of light touch. In tuberculoid and dimorphous leprosy, sensation is lost within the center of skin lesions, which are often annular. In lepromatous leprosy, the loss of light touch sensation typically occurs first in fingers and toes, while anesthesia in individual skin lesions may be variable.
- Nerve enlargement in tuberculoid and dimorphous leprosy occurs within or adjacent to specific skin lesions. In lepromatous leprosy, large peripheral nerves can be palpated. The easiest nerves to palpate are the posterior auricular nerve behind the ear and the ulnar nerve at the elbow (Fig. 29-2).
- The demonstration of M. leprae in the skin may be accomplished by a “slit skin smear” by experienced personnel. For those not experienced with the technique, it is easier and more reliable to simply perform a skin biopsy and request a special stain for the leprosy bacillus.
Hartzell JD, Zapor M, Peng S, Straight T: Leprosy: a case series and review, South Med J 97:1252–1256, 2004. |
