Leprosy diagnostic criteria
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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 is a disease with very different clinical presentations, depending on the immune response provided by the host. Therefore it is important to consider the different conditions that may mimic leprosy's presentation, particularly since the diagnosis of leprosy has a very serious psychological and social impact in a someone's life. To minimize the risk of reaching an erroneous diagnosis and inflicting stress and concern in the patient, criteria were developed to guide the diagnosis, which should only be communicated to the patient when a reasonable degree of certainty is present.
Diagnostic Criteria
Attending to the historic and social impact of leprosy in the population, a careful assessment of the patient should be made, before advancing the definitive diagnosis of leprosy. Even when suspected in the differential diagnosis, a reasonable degree of certainty is required, before communicating this to the patient.[1]
According to the WHO, for the diagnosis of leprosy, at least one of the following signs should be present:[1]
- Confirmed loss of sensation of a hypopigmented or erythematous skin patch. At this point is also important to count the number of skin lesions, in order to classify the type of leprosy, so that adequate therapy regimen may be started.
- A thickened peripheral nerve, with concomitant loss of sensation and/or weakness of the muscles it stimulates.
- Confirmation of acid-fast bacilli in the skin smear, although most people with leprosy will have a negative smear.
In the case of presence of all 3 criteria, then the sensitivity of the diagnosis has been reported to be around 97%.[2][3] When the patient does not fill the above criteria for the diagnosis, three options are available:[1]
- Discuss the case with colleagues specialized in leprosy and refer these cases to a healthcare center specialized in the condition.
- Reevaluate the diagnosis, considering the possibility of another skin disease.
- Reevaluate within 3 to 6 months. In case of leprosy, loss of sensation will then be observed and multi drug therapy would be initiated.
In case of absence of loss of sensation in the skin lesions and absence of enlarged nerves, but with suspicious signs, such as nodules or swellings on the face and/or earlobes, a skin smear test should be requested. A positive skin smear will confirm the diagnosis of leprosy, while a negative result, without other cardinal signs, would decrease the probability of leprosy diagnosis, in which case an alternative diagnosis should then be considered.[1]
References
- ↑ 1.0 1.1 1.2 1.3 "Enhanced global strategy for further reducing the disease burden due to leprosy (2011-2015)" (PDF).
- ↑ 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.
- ↑ Moschella SL (2004). "An update on the diagnosis and treatment of leprosy". J Am Acad Dermatol. 51 (3): 417–26. doi:10.1016/j.jaad.2003.11.072. PMID 15337986.