Leprosy other diagnostic studies
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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
Studies such as biopsy of skin lesions and skin smear tests have an important contribution 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, from the nasal mucosa and/or the ear lobe. This test has a sensitivity of 50% and a specificity of 100%. After collection of the [Laboratory specimen|specimen]], in order to visualize the bacteria, the Ziehl-Neelsen stain should be used. According to the Global Initiative from the WHO, in countries where leprosy is endemic, the diagnosis should be made based on the clinical signs and the results of the smear test, despite the availability of more sophisticated tests, such as serology tests.[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). According to the pole of leprosy in that patient, typical findings include:[1]
- Tuberculoid pole:
- Bacilli are commonly not observed.
- Granulomas commonly found, containing:
- Differentiated macrophages.
- Epithelioid cells.
- Giant cells.
- Lymphocytic infiltrate, with predominance of CD4+ T cells.
- Langerhans cells.
- Common nerve involvement.
- Absence of granuloma.
- Abundant Bacilli observed.
- Inflammatory infiltrate, with predominance of CD8+ T cells.
- Virchow cells loaded with bacilli.
- Loss of adnexal structures.
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. However, it is not a good test for paucibacillary cases. Due to its lack of sensitivity, the test is not in the United States.[1][7][8][9][10]
Polymerase Chain Reaction
The detection of the bacillus with PCR has high sensitivity and specificity. It is an important tool, particularly when histological features are inconclusive. However, it is a very expensive test, which limits its use, particularly 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.
- ↑ 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.
- ↑ Van Voorhis WC, Kaplan G, Sarno EN, Horwitz MA, Steinman RM, Levis WR; et al. (1982). "The cutaneous infiltrates of leprosy: cellular characteristics and the predominant T-cell phenotypes". N Engl J Med. 307 (26): 1593–7. doi:10.1056/NEJM198212233072601. PMID 6216407.
- ↑ 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.