Leprosy (Hansen's Disease)
The clinical presentation of non-pruritic skin lesions on the cheeks, elbows, and tibial shin with associated numbness over the lesions is pathognomonic for leprosy (Hansen's disease), and the patient requires immediate referral to a specialized leprosy treatment center for multidrug therapy with dapsone, rifampin, and clofazimine. 1, 2
Diagnostic Features
The combination of hypopigmented or erythematous plaques with loss of sensation is virtually diagnostic of leprosy and distinguishes it from all other dermatologic conditions:
- Sensory loss over skin lesions is the hallmark feature that differentiates leprosy from other hypopigmented or erythematous disorders 3, 2
- The distribution on cheeks, elbows, and tibial shin (cooler body areas) is characteristic, as Mycobacterium leprae preferentially affects these sites 3, 2
- Absence of pruritus is typical for leprosy lesions, unlike eczematous or allergic conditions 2
- Lesions may appear as hypopigmented or erythematous patches and plaques, occasionally with minimal scaling 3, 2
Critical Examination Steps
Perform these specific assessments immediately:
- Test sensation within each lesion using light touch and pinprick to document anesthesia 2
- Palpate peripheral nerves (ulnar, radial cutaneous, common peroneal, posterior tibial) for thickening or tenderness 1
- Examine the entire body for additional lesions, particularly on cooler areas (face, ears, extensor surfaces) 3
- Assess for nerve function deficits including weakness in hands or feet, which indicates neuritis requiring urgent treatment 1
Differential Diagnosis Exclusions
While other conditions may superficially resemble these lesions, the presence of numbness excludes them:
- Pityriasis alba presents with hypopigmented patches but maintains normal sensation and occurs primarily in children 4
- Lichen planus can present with hypopigmented lesions but is typically pruritic and lacks sensory changes 5, 6
- Psoriasis presents with erythematous plaques on elbows but has thick silvery scale, is pruritic, and has normal sensation 7, 8
- Lyme disease erythema migrans is expanding, typically >5 cm, and lacks sensory loss 7
Immediate Management Algorithm
Step 1: Confirm diagnosis
- Perform slit-skin smear from lesion edges and earlobes for acid-fast bacilli 2
- Obtain punch biopsy showing granulomatous inflammation with perineural infiltration 3, 2
Step 2: Classify disease type
- Paucibacillary (tuberculoid): Few lesions (<5), negative skin smears, requires 6 months treatment 1
- Multibacillary (lepromatous/borderline): Multiple lesions (≥5), positive smears, requires 12 months treatment 1
Step 3: Initiate multidrug therapy immediately
- Contact specialized leprosy treatment center (USPHS Carville, LA in United States) for treatment protocols 1
- Standard regimen combines dapsone, rifampin, and clofazimine 1
Critical Management Pitfalls
Monitor for reactional states during treatment:
- Type 1 reversal reaction: Swelling of existing lesions with neuritis occurring soon after treatment initiation requires high-dose corticosteroids to prevent permanent nerve damage 1
- Type 2 reaction (erythema nodosum leprosum): Fever with tender erythematous nodules occurs in ~50% of lepromatous patients in first year, requiring hospitalization if severe 1
- Neuritis is a medical emergency: Any nerve pain, tenderness, or new weakness requires immediate corticosteroid therapy and possible surgical decompression to prevent irreversible disability 1
Continue anti-leprosy treatment throughout reactional states unless specifically contraindicated, as stopping therapy worsens outcomes 1