Sean Klepper M.D.
Stephen Lyle, M.D., ...
Also known as: Hansen's disease
- Caused by Mycobacterium leprae
- Rare in the United States, although some cases are seen sporadically in Louisiana and Texas secondary to exposure to armadilloes
- Divided into several clinical forms: lepromatous, tuberculoid, borderline and indeterminate. Which form the disease takes in a particular patient is determined by the patient's immune status. This discussion will focus on tuberculoid leprosy, since it is the form that shows tuberculoid granulomas.
- The tuberculoid form of leprosy affects patients who are capable of mounting an effective cellular immune response against the organism. It presents with one to a few hypoesthetic, often scaly, annular patches or plaques, which are often hypopigmented, and frequently also with palpable peripheral nerves.
- Tuberculoid granulomas (defined as granulomas surrounded by a rim of lymphocytes)
- The granulomas may be linear, following the course of a peripheral nerve.
- No grenz zone, in contrast to lepromatous leprosy
- Few to no acid-fast bacteria on Fite stain (preferred to Ziehl-Neelson for M. leprae), as opposed to lepromatous leprosy, in which they are numerous. Immunohistochemical staining for AFB may be more fruitful in some cases.