Leprosy (cont.)
Are there different forms (classifications) of leprosy?
There are multiple forms of leprosy described in the literature. The forms of
leprosy are based on the person's immune response to M. leprae. A good immune
response can produce the so-called tuberculoid form of the disease, with limited
skin lesions and some asymmetric nerve involvement. A poor immune response can
result in the lepromatous form, characterized by extensive skin and symmetric
nerve involvement. Some patients may have aspects of both forms. Currently, two
classification systems exist in the medical literature: the WHO system and the
Ridley-Jopling system. The Ridley-Jopling system is composed of six forms or
classifications, listed below according to increasing severity of symptoms:
- Indeterminate leprosy: a few hypopigmented macules; can heal spontaneously,
persists or advances to other forms
- Tuberculoid leprosy: a few hypopigmented macules, some are large and some
become anesthetic (lose pain sensation); some neural involvement in which nerves
become enlarged; spontaneous resolution in a few years, persists or advances to
other forms
- Borderline tuberculoid leprosy: lesions like tuberculoid leprosy but smaller
and more numerous with less nerve enlargement; this form may persist, revert to
tuberculoid leprosy, or advance to other forms
- Mid-borderline leprosy: many reddish plaques that are asymmetrically
distributed, moderately anesthetic, with regional adenopathy (swollen lymph
nodes); the form may persist, regress to another form, or progress
- Borderline lepromatous leprosy: many skin lesions with macules (flat lesions)
papules (raised bumps), plaques, and nodules, sometimes with or without
anesthesia; the form may persist, regress or progress to lepromatous leprosy
- Lepromatous leprosy: Early lesions are pale macules (flat areas) that are
diffuse and symmetric; later many M. leprae organisms can be found in them.
Alopecia (hair loss) occurs; often patients have no eyebrows or eyelashes; as
the disease progresses, nerve involvement leads to anesthetic areas and limb
weakness; progression leads to aseptic necrosis (tissue death from lack of blood
to area), lepromas (skin nodules), and disfigurement of many areas including the
face; the lepromatous form does not regress to the other less severe forms.
The Ridley-Jopling classification is used globally in evaluating patients in
clinical studies. However, the WHO classification system is more widely used; it
has only two forms or classifications of leprosy. The 2009 WHO classifications
are simply based on the number of skin lesions as follows:
- Paucibacillary leprosy: skin lesions with no bacilli (M. leprae) seen in a
skin smear
- Multibacillary leprosy: skin lesions with bacilli (M. leprae) seen in a skin
smear
However, the WHO further modifies these two classifications with clinical
criteria because "…of the non-availability or non-dependability of the
skin-smear services. The clinical system of classification for the purpose of
treatment includes the use of number of skin lesions and nerves involved as the
basis for grouping leprosy patients into multibacillary (MB) and paucibacillary
(PB) leprosy." Investigators state that up to about four to five skin lesions constitutes
paucibacillary leprosy, while about five or more constitutes multibacillary
leprosy.
Mulitdrug therapy (MDT) with three antibiotics (dapsone, rifampicin, and clofazimine)
is used for multibacillary leprosy, while a modified MDT with two antibiotics (dapsone
and rifampicin) is recommended for paucibacillary leprosy. Paucibacillary
leprosy usually includes indeterminate, tuberculoid, and borderline tuberculoid
leprosy from the Ridley-Jopling classification, while multibacillary leprosy
usually includes the double (mid-) borderline, borderline lepromatous, and
lepromatous leprosy.
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