Leprosy

CASE 1

• A 31 year old man develops a patch of thickened, discolored skin over the left fronto-temporal region of his face (below). This plaque has been present for 3 months, but has not enlarged. There is no pain or itching associated with the rash.

• On examination, the vital signs are normal and the physical examination is remarkable only for the plaque on the forehead. The physician tests the sensation to pinprick over this area and finds that there is no perception of the pin over the involved skin.

• A punch biopsy of the plaque reveals confluent granulomas, but the acid-fast stain is negative.

Questions:

1. Why are there no acid-fast bacteria seen in the biopsy of this lesion?
2. What would you expect to isolate if you culture this biopsy for mycobacteria?
3. If the patient were given an intradermal skin test with an extract of proteins from Mycobacterium leprae, what reaction would you expect to see at the injection site after 48 hours?
4. With which antimicrobial agents should this patient be treated?

CASE 2

• A 43 year old man is admitted to the hospital after sustaining second and third degree burns to his right hand. The burn occurred while he was grilling kebabs over an open fire. One of the kebabs fell through the grill into the fire, and the patient reached in to retrieve it. During the next hour, he realized that his hand was swelling and blistering.

• An astute surgeon who treated the burn in the emergency department referred the patient for an evaluation in Internal Medicine for possible leprosy.

• On physical examination, the vital signs were normal. The patient had generalized thickening of the skin, particularly notable on the face. There was loss of the lateral eyebrows. Neurological examination revealed a generalized and symmetric loss of sensation but normal motor function. There was palpable swelling of the greater auricular nerves, radial and ulnar nerves, bilaterally.

• Smears were made from a nasal swab and from a swab of a superficial skin slit (made with a scalpel over the right posterior shoulder. The image below shows the acid stain from the nasal smear. The smear from the skin slit was similar.

Questions:

1. Why is this case difference from Case #1?
2. What would you expect to isolate if you culture the nasal swab for mycobacteria??
3. If the patient were given an intradermal skin test with an extract of proteins from Mycobacterium leprae, what reaction would you expect to see at the injection site after 48 hours?
4. How should this patient be treated?
5. Should the patient be isolated to prevent transmission to others?