Editing Leprosy (section)

== Diagnosis ==
[[File:Monofilament testing.jpg|alt=|thumb|right|Testing for loss of sensation with monofilament]]
In countries where people are frequently infected, a person is considered to have leprosy if they have one of the following two signs:
* Skin lesion consistent with leprosy and with definite sensory loss.<ref name="WHO Fact Sheet" />
* Positive skin smears.<ref name="WHO Fact Sheet" />

Skin lesions can be single or many, and usually [[Hypopigmentation|hypopigmented]], although occasionally reddish or copper-colored.<ref name="WHO Fact Sheet" /> The lesions may be flat ([[macule]]s), raised ([[papule]]s), or solid elevated areas ([[nodule (medicine)|nodular]]).<ref name="WHO Fact Sheet" /> Experiencing sensory loss at the skin lesion is a feature that can help determine if the lesion is caused by leprosy or by another disorder such as [[tinea versicolor]].<ref name="WHO Fact Sheet" /><ref>{{Cite web |url=https://www.internationaltextbookofleprosy.org/sites/default/files/ITL_2_3%20FINAL.pdf |title=International Textbook of Leprosy |vauthors=Moschella SL, Garcia-Albea V |date=September 2016 |website=Differential Diagnosis of Leprosy |page=3, Section 2.3 |access-date=4 July 2019 |archive-date=16 July 2020 |archive-url=https://web.archive.org/web/20200716191216/https://www.internationaltextbookofleprosy.org/sites/default/files/ITL_2_3%20FINAL.pdf |url-status=live }}</ref> Thickened nerves are associated with leprosy and can be accompanied by loss of sensation or muscle weakness, but muscle weakness without the characteristic skin lesion and sensory loss is not considered a reliable sign of leprosy.<ref name="WHO Fact Sheet" /> In some cases, the presence of [[Acid-fastness|acid-fast]] leprosy [[bacilli]] in skin smears is considered diagnostic; however, the diagnosis is typically made without laboratory tests, based on symptoms.<ref name="WHO Fact Sheet" /> If a person has a new leprosy diagnosis and already has a visible disability caused by leprosy, the diagnosis is considered late.<ref name="Rei2019" />

In countries or areas where leprosy is uncommon, such as the United States, diagnosis of leprosy is often delayed because healthcare providers are unaware of leprosy and its symptoms.<ref name="hrsa.gov" /> Early diagnosis and treatment prevent nerve involvement, the hallmark of leprosy, and the disability it causes.<ref name="WHO Fact Sheet" /><ref name="hrsa.gov">U.S. Department of Health and Human Services, Health Resources and Services Administration. (n.d.). National Hansen's disease (leprosy) program Retrieved from {{cite web |url=http://www.hrsa.gov/hansens/ |title=National Hansen's Disease (Leprosy) Program |access-date=12 May 2013 |url-status=dead |archive-url=https://web.archive.org/web/20110210202131/http://www.hrsa.gov/hansens/ |archive-date=10 February 2011 }}</ref> There is no recommended test to diagnose latent leprosy in people without symptoms.<ref name="WHO2018Tx" /> Few people with latent leprosy test positive for anti PGL-1.<ref name="Penna-2016" /> The presence of ''M. leprae'' bacterial [[DNA]] can be identified using a [[polymerase chain reaction]] (PCR)-based technique.<ref name="Martinez-2014">{{cite journal | vauthors = Martinez AN, Talhari C, Moraes MO, Talhari S | title = PCR-based techniques for leprosy diagnosis: from the laboratory to the clinic | journal = PLOS Neglected Tropical Diseases | volume = 8 | issue = 4 | pages = e2655 | date = April 2014 | pmid = 24722358 | pmc = 3983108 | doi = 10.1371/journal.pntd.0002655 | doi-access = free }}</ref> This molecular test alone is not sufficient to diagnose a person, but this approach may be used to identify someone who is at high risk of developing or transmitting leprosy such as those with few lesions or an atypical clinical presentation.<ref name="Martinez-2014" /><ref>{{cite journal | vauthors = Tatipally S, Srikantam A, Kasetty S | title = Polymerase Chain Reaction (PCR) as a Potential Point of Care Laboratory Test for Leprosy Diagnosis-A Systematic Review | journal = Tropical Medicine and Infectious Disease | volume = 3 | issue = 4 | pages = 107 | date = October 2018 | pmid = 30275432 | pmc = 6306935 | doi = 10.3390/tropicalmed3040107 | doi-access = free }}</ref> New approaches propose tools to diagnose leprosy through artificial intelligence.<ref>{{Cite journal |last1=Quilter |first1=Emily E. V. |last2=Butlin |first2=Cynthia Ruth |last3=Carrion |first3=Carme |last4=Ruiz-Postigo |first4=Jose-Antonio |date=1 June 2024 |title=The WHO Skin NTD mobile application – a paradigm shift in leprosy diagnosis through Artificial Intelligence? |url=https://leprosyreview.org/article/95/2/20-24030 |journal=Leprosy Review |volume=95 |issue=2 |pages=1–3 |doi=10.47276/lr.95.2.2024030 |issn=2162-8807 |access-date=27 May 2024 |archive-date=28 May 2024 |archive-url=https://web.archive.org/web/20240528055811/https://leprosyreview.org/article/95/2/20-24030 |url-status=live |doi-access=free }}</ref>

=== Classification ===
Several different approaches for classifying leprosy exist. There are similarities between the classification approaches.
* The World Health Organization (WHO) system distinguishes patients with 5 or fewer skin lesions and no bacilli in a skin smear as "paucibacillary" ("[[wikt:paucus#Latin|pauci]]-" refers to a small quantity) from patients with more lesions or detected bacilli as "multibacillary".<ref name="who-leprosy-factsheet-2025">{{Cite web |title=Leprosy |url=https://www.who.int/news-room/fact-sheets/detail/leprosy |access-date=2025-02-13 |website=www.who.int |language=en}}</ref> 
* The Ridley-Jopling scale provides five gradations.<ref name="pm hippopotamus id15176024">{{cite journal | vauthors = Singh N, Manucha V, Bhattacharya SN, Arora VK, Bhatia A | title = Pitfalls in the cytological classification of borderline leprosy in the Ridley-Jopling scale | journal = Diagnostic Cytopathology | volume = 30 | issue = 6 | pages = 386–388 | date = June 2004 | pmid = 15176024 | doi = 10.1002/dc.20012 | s2cid = 29757876 }}</ref><ref name="pmid5950347">{{cite journal | vauthors = Ridley DS, Jopling WH | title = Classification of leprosy according to immunity. A five-group system | journal = International Journal of Leprosy and Other Mycobacterial Diseases | volume = 34 | issue = 3 | pages = 255–273 | year = 1966 | pmid = 5950347 }}</ref><ref name="Andrews">{{cite book|title=Andrews' Diseases of the Skin: clinical Dermatology|url=https://archive.org/details/andrewsdiseasess00mdwi_659|url-access=limited| vauthors = James WD, Berger TG, Elston DM, Odom RB |publisher=Saunders Elsevier|year=2006|isbn=978-0-7216-2921-6|pages=[https://archive.org/details/andrewsdiseasess00mdwi_659/page/n354 344]–46}}</ref>
* The [[ICD-10]], though developed by the WHO, uses Ridley-Jopling and not the WHO system. It also adds an indeterminate ("I") entry.<ref name="news-medical">"What Is Leprosy?"| from News-Medical.Net – Latest Medical News and Research from Around the World. Web. 20 November 2010. {{cite news |url=http://www.news-medical.net/health/What-is-Leprosy.aspx |title=What is Leprosy? |newspaper=News-Medical.net |access-date=14 May 2013 |url-status=live |archive-url=https://web.archive.org/web/20130606033328/http://www.news-medical.net/health/What-is-Leprosy.aspx |archive-date=6 June 2013 |date=18 November 2009 }}.</ref>
* In [[Medical Subject Headings|MeSH]], three groupings are used.
{{Clear}}
{| class="wikitable"
|-
! WHO
! Ridley-Jopling
! [[ICD-10]]
! [[Medical Subject Headings|MeSH]]
! Description
! [[Lepromin]] test
|-
| Paucibacillary
| tuberculoid ("TT"),<br />borderline<br />tuberculoid ("BT")
| style="white-space:nowrap;"| A30.1, A30.2
| Tuberculoid
| It is characterized by one or more [[Hypopigmentation|hypopigmented]] skin macules and patches where skin sensations are lost because of damaged peripheral nerves that have been attacked by the human host's immune cells. TT is characterized by the formation of [[epithelioid cell]] granulomas with a large number of [[epithelioid cell]]s. In this form of leprosy, ''Mycobacterium leprae'' are either absent from the lesion or occur in very small numbers. This type of leprosy is most benign.<ref name="pmid22988457"/><ref name="pmid24937811">{{cite journal | vauthors = Lastória JC, Abreu MA | title = Leprosy: a review of laboratory and therapeutic aspects--part 2 | journal = Anais Brasileiros de Dermatologia | volume = 89 | issue = 3 | pages = 389–401 | date = 2014 | pmid = 24937811 | pmc = 4056695 | doi = 10.1590/abd1806-4841.20142460 | doi-access = free }}</ref>

| Positive
|-
| Multibacillary
| style="white-space:nowrap;"|midborderline<br />or<br />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.{{citation needed|date=May 2021}}
|Negative
|-
| Multibacillary
| borderline lepromatous ("BL"),<br />and lepromatous ("LL")
| A30.4, A30.5
| Lepromatous
| It is associated with symmetric skin [[lesion]]s, [[Nodule (medicine)|nodules]], [[Plaque (dermatology)|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. Loss of eyebrows and lashes can be seen in advanced disease.<ref>{{Cite web|url=https://internationaltextbookofleprosy.org/chapter/diagnosis-leprosy|title=Clinical Diagnosis of Leprosy|author1=Kumar, Bhushan|author2=Uprety, Shraddha|author3=Dogra, Sunil|date=11 February 2016|website=International Textbook of Leprosy|access-date=12 February 2019|archive-date=13 February 2019|archive-url=https://web.archive.org/web/20190213064205/https://internationaltextbookofleprosy.org/chapter/diagnosis-leprosy|url-status=live}}</ref> LL is characterized by the absence of [[epithelioid cell]]s in the lesions. In this form of leprosy, ''Mycobacteria leprae'' are found in lesions in large numbers. This is the most unfavorable clinical variant of leprosy, which occurs with a generalized lesion of the skin, mucous membranes, eyes, peripheral nerves, lymph nodes, and internal organs.<ref name="pmid22988457" /><ref name="pmid24937811" /> [[Histoid leprosy]] is a rare variation of multibacillary, lepromatous leprosy.
| Negative
|}

Leprosy may also occur with only neural involvement, without skin lesions.<ref name="WHO Fact Sheet" /><ref name="pmid12883921">{{cite journal | vauthors = Jardim MR, Antunes SL, Santos AR, Nascimento OJ, Nery JA, Sales AM, Illarramendi X, Duppre N, Chimelli L, Sampaio EP, Sarno EP | title = Criteria for diagnosis of pure neural leprosy | journal = Journal of Neurology | volume = 250 | issue = 7 | pages = 806–809 | date = July 2003 | pmid = 12883921 | doi = 10.1007/s00415-003-1081-5 | s2cid = 20070335 }}</ref><ref name="pmid17120509">{{cite journal | vauthors = Mendiratta V, Khan A, Jain A | title = Primary neuritic leprosy: a reappraisal at a tertiary care hospital | journal = Indian Journal of Leprosy | volume = 78 | issue = 3 | pages = 261–267 | year = 2006 | pmid = 17120509 }}</ref><ref name="pmid10979277">{{cite journal | vauthors = Ishida Y, Pecorini L, Guglielmelli E | title = Three cases of pure neuritic (PN) leprosy at detection in which skin lesions became visible during their course | journal = Nihon Hansenbyo Gakkai Zasshi = Japanese Journal of Leprosy | volume = 69 | issue = 2 | pages = 101–106 | date = July 2000 | pmid = 10979277 | doi = 10.5025/hansen.69.101 | doi-access = free }}</ref><ref name="pmid8711979">{{cite journal | vauthors = Mishra B, Mukherjee A, Girdhar A, Husain S, Malaviya GN, Girdhar BK | title = Neuritic leprosy: further progression and significance | journal = Acta Leprologica | volume = 9 | issue = 4 | pages = 187–194 | year = 1995 | pmid = 8711979 }}</ref><ref name="pmid1406021">{{cite journal | vauthors = Talwar S, Jha PK, Tiwari VD | title = Neuritic leprosy: epidemiology and therapeutic responsiveness | journal = Leprosy Review | volume = 63 | issue = 3 | pages = 263–268 | date = September 1992 | pmid = 1406021 | doi = 10.5935/0305-7518.19920031 | doi-access = free }}</ref>