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
Leprosy may be divided according to different systems of classification, from which two of them, the Ridley Jopling classification and the WHO classification are the most broadly used. These classifications are based on clinical, bacteriological and histopathological features presented by the patient and help to identify the class of leprosy, thereby determining the prognosis and the treatment regimen to give to that particular patient.[1][2][3]
Classification
Leprosy may present among different patients, or even in one single patient throughout the course of the disease, with a multitude of clinical, histopathological and bacterial states. By attributing a class to a certain manifestation of the disease in one patient, it is possible to determine his prognosis, infectivity rate and the type of treatment to administrate in that patient. [1]
There are several different approaches for classifying leprosy however, some similarities do exist:
- The World Health Organization system distinguishes "paucibacillary" and "multibacillary" based upon the proliferation of bacteria[4]
- The SHAY scale provides five gradations.[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, three groupings are used.
| 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) |
However, the two most common classifications include:
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 hipopigmented 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]
- Cutaneous
- Neurological
- Biopsy findings
- Immunological status
- Sum of acid-fast bacilli in the dermis.
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]
- In case of progression towards the tuberculoid pole, it means the patient's cell-mediated immunity is increasing, thereby being associated with inflammation of the nerves and skin.
- in case of progression towards the lepromatous pole, usually occurring before treatment is initiated and is compatible with loss of cell-mediated immunity.
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 defined a more simple and straightforward classification, according to the number of skin lesions present. This classification is due to be used there is lack of laboratory support of clinical expertise, in which case, the disease will be classified as paucibacillary leprosy, when five or less skin lesions are present but no bacilli is present on skin smears; or multibacillary leprosy, when more than six skin lesions are present, with a possibly positive skin smear. However, despite useful in certain occasions, this method may lead to misclassification of some patients, resulting in undertreatment of some cases.[8]
References
- ↑ 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.
- ↑ 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.
- ↑ 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.
- ↑ Smith DS (2008-08-19). "Leprosy: Overview". eMedicine Infectious Diseases. Retrieved 2010-02-01.
- ↑ 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) - ↑ 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.
- ↑ "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>.
- ↑ 8.0 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.