eMedicine Specialties > Infectious Diseases > Skin and Soft-Tissue Infections
Leprosy: Differential Diagnoses & Workup
Updated: Aug 19, 2008
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
- Multimedia
Differential Diagnoses
Other Problems to Be Considered
Sensory loss (hypoesthesia) or neuropathy
Amyloidosis
Diabetic neuropathy
Neuropathies due to medications (ie, stavudine, didanosine, acetazolamide, vincristine, gabapentin [Neurontin], isoniazid)
Refsum disease
Sarcoidosis
Vitamin B-12 or folate deficiency
Skin lesions - Flat and hypopigmented
Contact dermatitis
Localized scleroderma
Nevus depigmentosus (congenital lesion)
Onchocerciasis
Pityriasis alba
Pityriasis versicolor
Post–kala-azar dermal leishmaniasis
Seborrheic dermatitis
Tinea corporis (and all dermatophytes)
Vitiligo
Yaws
Skin lesions - Raised and pigmented
Atypical necrobiosis of the face
Cutaneous leishmaniasis
Cutaneous tuberculosis
Follicular mucinosis
Generalized thickening of skin
Granuloma annulare
Granuloma multiforme
Kaposi sarcoma
Lupus erythematosus
Lupus vulgaris
Mycobacterium marinum infection
Myxoedema
Neurofibromatosis
Pachydermoperiostitis
Pityriasis rosea
Psoriasis
Scleroderma
Syphilis
Wegener granulomatosis
Workup
Laboratory Studies
The WHO case definition of leprosy is M leprae infection in an individual who has not completed a course of treatment and has one or more of the following:
- Hypopigmented or reddish skin lesions with loss of sensation
- Involvement of the peripheral nerves as demonstrated by their thickening and associated loss of sensation
- Skin smear positive for acid-fast bacilli
- Skin biopsy, nasal smears, or both are used to assess for acid-fast bacilli using Fite stain. Biopsies should be full dermal thickness taken from an edge of the lesion that appears most active.7
- Serologic assays can be used to detect phenolic glycolipid-1 (specific for M leprae) and lipoarabinomannan (commonly seen in mycobacteria).7
- Molecular probes detect 40-50% of cases missed on prior histologic evaluation. Since probes require a minimum amount of genetic material (ie, 104 DNA copies), they can fail to identify paucibacillary leprosy.
Laboratory tests related to drug treatment follow-up include the following:
- CBC count
- Creatinine level
- Liver function tests
Other Tests
- Immunologic tests include the following:
- Lepromin skin test (not available in the United States): Although not diagnostic of exposure to or infection with M leprae, this test assesses a patient's ability to mount a granulomatous response against a skin injection of killed M leprae. Patients with tuberculoid leprosy or borderline lepromatous leprosy typically have a positive response (>5 mm). Patients with lepromatous leprosy typically have no response.
- Phenolic glycolipid-1: This is a specific serologic test based on the detection of antibodies to phenolic glycolipid-1. This test yields a sensitivity of 95% for the detection of lepromatous leprosy but only 30% for tuberculoid leprosy.
- Polymerase chain reaction (PCR): PCR and recombinant DNA technology have allowed for the development of gene probes with M leprae –specific sequences. This technology can be used to identify the mycobacterium in biopsy samples, skin and nasal smears, and blood and tissue sections.
- Lymphocyte migration inhibition test (LMIT): As determined by a lymphocyte transformation and LMIT, cell-mediated immunity to M leprae is absent in patients with lepromatous leprosy but present in those with tuberculoid leprosy.
- Contact or family screening for history of leprosy
Procedures
- Skin biopsy samples stained with hematoxylin-eosin and Fite-Faraco are the primary basis for laboratory diagnosis and categorization. A full-thickness skin biopsy sample should be taken from an advancing border of an active lesion and should include dermis and epidermis. Skin smears that demonstrate acid-fast bacilli strongly suggest a diagnosis of leprosy, but the bacilli may not be demonstrable in tuberculoid (paucibacillary) leprosy.
- A nerve biopsy can be beneficial in ruling out diseases such as hereditary neuropathies or polyarteritis nodosa. Nerve biopsies may also help identify abnormalities in patients with subclinical leprosy and may be the only way to definitively diagnose completely neuropathic forms of leprosy. If a nerve biopsy is needed to confirm diagnosis, a purely sensory nerve (eg, sural or radial cutaneous nerve) should be used. This procedure is rarely necessary.6
Histologic Findings
Findings vary but can include dermatitis, giant cells, infiltration of nerve bundles with mononuclear cells, and granulomas. Lepromatous lesions generally contain numerous acid-fast bacilli and fat-laden macrophages with a paucity of lymphocytes (see Image 8). In contrast, tuberculoid lesions contain few-to-no acid-fast bacilli but manifest granulomatous changes with epithelial cells and lymphocytes. The immunopathologic spectrum of leprosy has been delineated in the Leprosy topic in eMedicine's Neurology volume.
Staging
Leprosy is staged or graded based on microscopy findings to classify cases as paucibacillary or multibacillary so that duration and type of drug therapy can be determined.
More on Leprosy |
| Overview: Leprosy |
 Differential Diagnoses & Workup: Leprosy |
| Treatment & Medication: Leprosy |
| Follow-up: Leprosy |
| Multimedia: Leprosy |
| References |
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References
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Scollard DM, Adams LB, Gillis TP, et al. The continuing challenges of leprosy. Clin Microbiol Rev. Apr 2006;19(2):338-81. [Medline].
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[Best Evidence] Van Veen NH, Nicholls PG, Smith WC, Richardus JH. Corticosteroids for treating nerve damage in leprosy. Cochrane Database Syst Rev. Apr 18 2007;CD005491. [Medline].
Bakker MI, Hatta M, Kwenang A, et al. Risk factors for developing leprosy--a population-based cohort study in Indonesia. Lepr Rev. Mar 2006;77(1):48-61. [Medline].
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Deps PD, Guedes BV, Bucker Filho J, Andreatta MK, Marcari RS, Rodrigues LC. Characteristics of known leprosy contact in a high endemic area in Brazil. Lepr Rev. Mar 2006;77(1):34-40. [Medline].
Jacobson RR, Krahenbuhl JL, Yoder L. Overview of Leprosy. UpToDate. 2006.
Leprosy. World Health Organization. Available at www.who.org.
Moschella SL. An update on the diagnosis and treatment of leprosy. J Am Acad Dermatol. Sep 2004;51(3):417-26. [Medline].
Rao PS, Sugamaran DS, Richard J, et al. Multi-centre, double blind, randomized trial of three steroid regimens in the treatment of type-1 reactions in leprosy. Lepr Rev. Mar 2006;77(1):25-33. [Medline].
Sridharan R, Lorenzo N, Narasimhan L. Leprosy. eMedicine. 2005.
van Beers SM, Hatta M, Klatser PR. Patient contact is the major determinant in incident leprosy: implications for future control. Int J Lepr Other Mycobact Dis. Jun 1999;67(2):119-28. [Medline].
Further Reading
Keywords
leprosy, Hansen's disease, Hansen disease, Mycobacterium leprae, M leprae, tuberculoid leprosy, TT leprosy, lepromatous leprosy, LL leprosy, BT leprosy, midborderline leprosy, BB leprosy, borderline lepromatous leprosy, BL leprosy, paucibacillary leprosy, PB leprosy, multibacillary leprosy, MB leprosy, indeterminate leprosy, borderline leprosy
