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Hansen's Disease / Leprosy (Mycobacterium leprae)
2013 Case Definition

CSTE Position Statement(s)

  • 12-ID-01

Clinical Criteria

A chronic bacterial disease characterized by the involvement primarily of skin as well as peripheral nerves and the mucosa of the upper airway. Clinical forms of Hansen"s disease represent a spectrum reflecting the cellular immune response to Mycobacterium leprae. The following characteristics are typical of the major forms of the disease, though these classifications are assigned after a case has been laboratory confirmed.

  • Tuberculoid: one or a few well-demarcated, hypopigmented, and hypoesthetic or anesthetic skin lesions, frequently with active, spreading edges and a clearing center; peripheral nerve swelling or thickening also may occur
  • Lepromatous: a number of erythematous papules and nodules or an infiltration of the face, hands, and feet with lesions in a bilateral and symmetrical distribution that progress to thickening of the skin, possibly with reduced sensation.
  • Borderline (dimorphous): skin lesions characteristic of both the tuberculoid and lepromatous forms
  • Indeterminate: early lesions, usually hypopigmented macules, without developed tuberculoid or lepromatous features but with definite identification of acid-fast bacilli in Fite stained sections

Laboratory Criteria for Diagnosis


  • Demonstration of acid fast bacilli in skin or dermal nerve from a biopsy of a skin lesion using Fite stain, without growth of mycobacteria on conventional media (if done)
  • Identification of noncaseating granulomas with peripheral nerve involvement, without growth of mycobacteria on conventional media (if done)

Case Classification


A clinically compatible illness with confirmatory laboratory results.