Signs and Symptoms of Leprosy (Hansen Disease)
Cardinal Clinical Features
Leprosy diagnosis requires one or more of three cardinal signs: hypopigmented or erythematous skin patches with definite loss of sensation, thickened peripheral nerves, and acid-fast bacilli on skin smears or biopsy. 1
Skin Manifestations
Tuberculoid (Paucibacillary) Form
- One or few well-demarcated, hypopigmented skin lesions with active spreading edges and clearing centers 2, 3
- Lesions demonstrate complete anesthesia (loss of sensation) which is pathognomonic for leprosy 4
- Peripheral nerve swelling may be palpable near affected skin areas 3
Lepromatous (Multibacillary) Form
- Multiple erythematous papules and nodules with bilateral and symmetrical distribution affecting face, hands, and feet 2, 4
- Diffuse skin infiltration progressing to skin thickening with loss of normal skin architecture 4
- Nodules (lepromas) develop and may ulcerate 4
- Lesions range from porcelain-white to erythematous coloration 4
Neurological Manifestations
- Peripheral nerve damage is the hallmark complication, with M. leprae primarily infecting Schwann cells 1
- Thickened peripheral nerves are palpable on examination 3, 1
- Sensory loss in affected skin areas, particularly in hands and feet 5
- Weakness and numbness in extremities 5
- "Silent neuropathy" may occur where nerves are functionally impaired before obvious symptoms develop 6
Upper Respiratory Involvement
- Nasal symptoms from upper respiratory mucosa involvement 3
- Nasal stuffiness or epistaxis may occur in lepromatous disease 2
Ocular Manifestations
- Eye pain or loss of vision from direct ocular involvement 5
- Lagophthalmos (inability to close eyelids) from facial nerve damage 6
Disease Spectrum Characteristics
The clinical presentation exists on a spectrum based on host T-cell-mediated immune response to M. leprae 2, 6:
- Tuberculoid pole: Strong cellular immunity, few lesions, low bacterial load 2
- Lepromatous pole: Weak cellular immunity, multiple lesions, high bacterial load 2
- Borderline forms: Intermediate presentations between the two poles 3
Critical Diagnostic Pitfalls
- In non-endemic areas, leprosy is frequently misdiagnosed as tinea versicolor, vitiligo, or other common dermatoses because clinicians fail to consider it 7
- Anesthesia in skin lesions distinguishes leprosy from most mimics and must be actively tested 4
- Early recognition is crucial as nerve damage is irreversible once established 8
- Patients from endemic areas (Brazil, India, Southeast Asia, Africa) presenting with hypopigmented patches warrant high suspicion 7
Immunologic Reactions
- Type 1 reversal reactions: Acute inflammation in existing lesions with increased erythema and edema 6, 5
- Type 2 reactions (erythema nodosum leprosum): Painful subcutaneous nodules, fever, and systemic symptoms 6, 5
- These reactions can occur before, during, or after treatment and represent immune-mediated exacerbations requiring prompt corticosteroid therapy while continuing antibacterial treatment 5