Pediatric Leprosy Workup

Updated: Aug 02, 2018
  • Author: Benjamin Estrada, MD; Chief Editor: Russell W Steele, MD  more...
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Workup

Laboratory Studies

While in contact with patients with leprosy, healthcare workers should employ standard precautions. It has been suggested that M leprae is sensitive to ultraviolet light, and this sensitivity may be useful in sterilization and disinfection practices. [15]

M leprae cannot be cultured in vivo; however, some laboratory studies are available that can be useful in the diagnosis of leprosy. Measurement of phenolic glycolipid-1 antibodies may be helpful in epidemiologic studies and follow-up treatment.

Detection of M leprae by polymerase chain reaction (PCR) is promising; however, PCR detection is not widely available and has not been standardized. [16] RNA gene probes have been used to assist in the diagnosis and response to treatment among patients with paucibacillary (PB) and multibacillary (MB) disease. The absence of M leprae rRNA in skin samples of previously diagnosed patients correlates with response to treatment. Probes targeting 16S rRNA and 16S rDNA have been used in the diagnosis of smear-negative MB disease. [17, 18, 19, 20]

Drug resistance can be tested in vivo by inoculation of mouse footpad. This type of test is not widely accessible, and results are not usually available until 6 months after inoculation. [21]

Lepromin testing is an intradermal skin test that contains heat-killed M leprae. Patients with PB leprosy and individuals who are asymptomatic but live in endemic areas usually present an area of induration after the antigen administration; however, patients with MB leprosy rarely react to the administration of this antigen. The use of this test has no practical diagnostic value and has recently been discouraged.

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Tissue Analysis and Histologic Findings

Skin biopsies and smears are helpful not only in establishing the diagnosis of leprosy but also in the process of establishing the difference between PB and MB disease. Skin biopsy specimens obtained from patients with leprosy should always be stained with hematoxylin and eosin (H&E) and an acid-fast stain.

In PB leprosy, giant cells in skin and nerves may accompany accumulation of epithelioid-lymphocyte granulomas. Bacilli are rare in this type of leprosy, and they are not present in nerves. In LL leprosy, bacilli are abundant; they can be observed in the areas surrounding blood vessels and are also present in nerves.

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