Leprosy classification

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: João André Alves Silva, M.D. [2]

Overview

The Ridley Jopling classification and the WHO classification are the two most widely used systems to classify Leprosy. These classification systems are based on clinical, microbiologic and histopathological features, and are used to determine the patient's prognosis and the treatment regimen.[1][2][3]

Classification

Leprosy may present among different patients, or even in one single patient throughout the course of the disease, with a variety of clinical, histopathological and bacterial manifestations. Subclassification of Leprosy type determins prognosis, infectivity rate and the appropriate treatment. [1] The two most common classifications include the WHO and the Ridley-Jopling classification.

There are several subclassification schemes for the diagnosis of Leprosy:

  • The World Health Organization system distinguishes "paucibacillary" and "multibacillary" based upon the proliferation of bacteria[4]
  • The SHAY scale provides five subclassifications.[5][6]
  • The ICD-10, though developed by the WHO, uses Ridley-Jopling and not the WHO system. It also adds an indeterminate ("I") entry.[7]
  • In MeSH, there are three sublclasses.
WHO Ridley-Jopling ICD-10 MeSH Description Lepromin test Immune target
Paucibacillary tuberculoid ("TT"), borderline tuberculoid ("BT") A30.1, A30.2 Tuberculoid It is characterized by one or more hypopigmented skin macules and anaesthetic patches, where skin sensations are lost because of damaged peripheral nerves that have been attacked by the human host's immune cells. Positive bacillus (Th1)
Multibacillary midborderline or borderline ("BB") A30.3 Borderline Borderline leprosy is of intermediate severity and is the most common form. Skin lesions resemble tuberculoid leprosy but are more numerous and irregular; large patches may affect a whole limb, and peripheral nerve involvement with weakness and loss of sensation is common. This type is unstable and may become more like lepromatous leprosy or may undergo a reversal reaction, becoming more like the tuberculoid form.
Multibacillary borderline lepromatous ("BL"), and lepromatous ("LL") A30.4, A30.5 Lepromatous It is associated with symmetric skin lesions, nodules, plaques, thickened dermis, and frequent involvement of the nasal mucosa resulting in nasal congestion and epistaxis (nose bleeds), but, typically, detectable nerve damage is late. Negative plasmid inside bacillus (Th2)


Ridley Jopling classification

This classification provides an optimal organization of the different presentations of the disease, being able to include clinic, histopathology and bacterial index in each category, thereby providing an insight of the patient's immune response to the disease. [1] The status of disease will range from the tuberculoid or pauci-bacillary pole, in which is present 1 to 3 well-defined lesions with a central hypopigmented area, with hipoesthesia, a well-developed immune response from the patient, with evidence of an adequate granulomatous inflammation and presence of very few acid-fast bacilli; to the lepromatous or multi-bacillary pole, in which patients presents with numerous undefined nodular lesions throughout the body, with a weak immune response towards the bacteria, histological evidence of foamy macrophages in dermis filled with a great number of mycobacteria. On this last pole, it is important to notice that even though the immune system is not capable of mounting an immune response towards the bacilli, patients are still immunocompetent for other diseases. For this classification contribute the following elements:[8]

Between these two poles, there is also the intermediate, dimorphous or borderline state. This last category is subdivided into 3 subcategories, depending on the pole each subcategory has more similarities with, which include:

  • Borderline Tuberculoid, or BT
  • Mid-Borderline, Borderline-Borderline, or BB
  • Borderline Lepromatous, or BL

This intermediate category is considered to be the one where the disease usually begins. It will then progress to one of the poles: [1]

Some patients show evidence of early unspecific lesions and nerve infiltrates, lacking the required criteria for being classified as above mentioned. These patients are included in a specific category called indeterminate. This category should only be used when there is diagnostic proof of leprosy, from a biopsy sample showing evidence of mycobacteria leprae and perineural infiltrates, but the disease is not advanced enough to show the clear patient position in the leprosy classification.

WHO classification

The WHO organization has defined a more simple and straightforward classification, according to the number of skin lesions present. This classification is due to be used when there is lack of laboratory support or clinical expertise, in which case, the disease will be classified as paucibacillary leprosy or multibacillary leprosy. However, despite useful in certain occasions, this method may lead to misclassification of some patients, resulting in undertreatment of some cases.[8]

This classification allows, however, for a rapid diagnosis, selection and initiation of treatment, according to the class of leprosy:[9]

Paucibacillary or PB

Multibacillary or MB

If a skin smear is done and shows a positive result, then that patient will immediately be classified as a multibacillary patient, irrespective of the number of skin lesions identified on physical examination.

References

  1. 1.0 1.1 1.2 1.3 Walker, Stephen L.; Lockwood, Dina N.J. (2007). "Leprosy". Clinics in Dermatology. 25 (2): 165–172. doi:10.1016/j.clindermatol.2006.05.012. ISSN 0738-081X.
  2. Eichelmann, K.; González González, S.E.; Salas-Alanis, J.C.; Ocampo-Candiani, J. (2013). "Leprosy. An Update: Definition, Pathogenesis, Classification, Diagnosis, and Treatment". Actas Dermo-Sifiliográficas (English Edition). 104 (7): 554–563. doi:10.1016/j.adengl.2012.03.028. ISSN 1578-2190.
  3. Bhat, Ramesh Marne; Prakash, Chaitra (2012). "Leprosy: An Overview of Pathophysiology". Interdisciplinary Perspectives on Infectious Diseases. 2012: 1–6. doi:10.1155/2012/181089. ISSN 1687-708X.
  4. Smith DS (2008-08-19). "Leprosy: Overview". eMedicine Infectious Diseases. Retrieved 2010-02-01.
  5. Singh N, Manucha V, Bhattacharya SN, Arora VK, Bhatia A (2004). "Pitfalls in the cytological classification of borderline leprosy in the Ridley-Jopling scale". Diagn. Cytopathol. 30 (6): 386–8. doi:10.1002/dc.20012. PMID 15176024. Unknown parameter |month= ignored (help)
  6. Ridley DS, Jopling WH (1966). "Classification of leprosy according to immunity. A five-group system". Int. J. Lepr. Other Mycobact. Dis. 34 (3): 255–73. PMID 5950347.
  7. "What Is Leprosy?" THE MEDICAL NEWS | from News-Medical.Net - Latest Medical News and Research from Around the World. Web. 20 Nov. 2010. <http://www.news-medical.net/health/What-is-Leprosy.aspx>.
  8. 8.0 8.1 Pardillo FE, Fajardo TT, Abalos RM, Scollard D, Gelber RH (2007). "Methods for the classification of leprosy for treatment purposes". Clin Infect Dis. 44 (8): 1096–9. doi:10.1086/512809. PMID 17366457.
  9. "Enhanced global strategy for further reducing the disease burden due to leprosy (2011-2015)" (PDF).


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