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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
Biopsy of skin lesions and skin smear tests are important for the diagnosis of leprosy in patients whose clinical examination is suspicious of the disease.
Other Diagnostic Studies
Smear test
May be obtained from any skin lesion, nasal mucosa and/or ear lobe.
This test has sensitivity of 50% and specificity of 100%. After collection of the specimen, to visualize the bacteria, the Ziehl-Neelsen stain should be used. Developing countries with low resources and innovative techniques should base the diagnosis on clinical signs, and results from the smear test.[1][2][3][4]
Skin Biopsy
A biopsy of the skin lesion should be performed and stained according to the Fite-Faraco technique (a especially designed protocol for staining the leprosy bacilli). [1]
Lepromin Test
Although not a diagnostic test, the lepromin skin test is used to classify and determine the prognosis of the condition. For this test it is used the inactivated form of Mycobacterium leprae, extracted from lepromas, as follows:[1]
- Intradermal injection of lepromin (the antigen) on the forearm
- The result will then be interpreted at 2 moments:
- 1. Early reaction (Fernandez reaction):
- Good sensitivity
- Cross reactivity with other mycobacteria
- May be read at 24 or 48h
- 2. Later reaction (Mitsuda reaction):
- Read at the 21st day
- Positive result is expressed by a nodule measuring more than 5 mm
- Indicative of resistance to the mycobacterium leprae
Serology
The serology test using the PGL-1 antibody titer (Phenolic Glycolipid 1) is a useful diagnostic tool, particularly for multibacillary cases. Yet, it is not a good test for paucibacillary leprosy. Due to its lack of sensitivity, the test is not available in the United States.[1][5][6][7][8]
Polymerase Chain Reaction
The detection of the bacillus with PCR has high sensitivity and specificity. It is an important tool, particularly when histologic features are inconclusive. However, the cost limits its use in developing countries with very little resources and infrastructures.[1]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 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.
- ↑ Hatta M, van Beers SM, Madjid B, Djumadi A, de Wit MY, Klatser PR (1995). "Distribution and persistence of Mycobacterium leprae nasal carriage among a population in which leprosy is endemic in Indonesia". Trans R Soc Trop Med Hyg. 89 (4): 381–5. PMID 7570870.
- ↑ Aggarwal A, Pandey A (2010). "Inverse sampling to study disease burden of leprosy". Indian J Med Res. 132: 438–41. PMID 20966523.
- ↑ Ramaprasad P, Fernando A, Madhale S, Rao JR, Edward VK, Samson PD; et al. (1997). "Transmission and protection in leprosy: indications of the role of mucosal immunity". Lepr Rev. 68 (4): 301–15. PMID 9503866.
- ↑ Silva EA, Iyer A, Ura S, Lauris JR, Naafs B, Das PK; et al. (2007). "Utility of measuring serum levels of anti-PGL-I antibody, neopterin and C-reactive protein in monitoring leprosy patients during multi-drug treatment and reactions". Trop Med Int Health. 12 (12): 1450–8. doi:10.1111/j.1365-3156.2007.01951.x. PMID 18076551.
- ↑ Banerjee S, Sarkar K, Gupta S, Mahapatra PS, Gupta S, Guha S; et al. (2010). "Multiplex PCR technique could be an alternative approach for early detection of leprosy among close contacts--a pilot study from India". BMC Infect Dis. 10: 252. doi:10.1186/1471-2334-10-252. PMC 2942881. PMID 20735843.
- ↑ Martins AC, Miranda A, Oliveira ML, Bührer-Sékula S, Martinez A (2010). "Nasal mucosa study of leprosy contacts with positive serology for the phenolic glycolipid 1 antigen". Braz J Otorhinolaryngol. 76 (5): 579–87. PMID 20963340.
- ↑ Butlin CR, Soares D, Neupane KD, Failbus SS, Roche PW (1997). "IgM anti-phenolic glycolipid-I antibody measurements from skin-smear sites: correlation with venous antibody levels and the bacterial index". Int J Lepr Other Mycobact Dis. 65 (4): 465–8. PMID 9465156.