Leprosy Diagnosis and Treatment

Introduction to Leprosy

Leprosy is a chronic bacterial infection caused by Mycobacterium leprae that primarily affects the skin, peripheral nerves, and upper respiratory mucosa, with transmission occurring through prolonged close contact via respiratory droplets, though it has low pathogenicity and low virulence despite being highly infective 1, 2, 3

The disease manifests as a spectrum based on the host's cellular immune response to M. leprae, ranging from tuberculoid (strong cell-mediated immunity) to lepromatous (weak cell-mediated immunity) forms 1, 2, 4
Skin lesions in the tuberculoid form are characterized by one or a few well-demarcated, hypopigmented, and anesthetic skin lesions with active spreading edges and clearing centers 1, 2, 4
The lepromatous form is characterized by multiple erythematous papules and nodules or infiltration of the face, hands, and feet with bilateral and symmetrical distribution that progresses to skin thickening 1, 2, 4

The gold standard for diagnosis is the demonstration of acid-fast bacilli in skin or dermal nerve, obtained from full-thickness skin biopsy of a lepromatous lesion 1, 2, 3, 4

The World Health Organization recommends multidrug therapy (MDT) regimens for the treatment of leprosy, which includes rifampin, clofazimine, and dapsone for multibacillary leprosy, and rifampin and dapsone for paucibacillary leprosy 5, 6
G6PD deficiency screening is mandatory before initiating dapsone due to the risk of hemolytic anemia and methemoglobinemia 5, 6
Baseline ECG is required before clofazimine due to the risk of QT interval prolongation 5, 6
Regular monitoring of complete blood count and liver function tests is necessary during dapsone therapy 5, 6

Treatment should be continued during pregnancy as benefits outweigh risks, with close monitoring required 6
Clofazimine has been well-tolerated in pediatric leprosy trials at 1-2 mg/kg/day (maximum 100 mg) 6

Treatment should not be interrupted due to skin complications or wound healing 5
Leprosy reactions (Type 1 reversal reactions, Type 2 erythema nodosum leprosum) require anti-inflammatory management but continuation of MDT 5, 6
Type 1 reversal reactions should be treated with corticosteroids while continuing MDT 5

Premature treatment discontinuation due to leprosy reactions worsens outcomes; reactions require anti-inflammatory therapy while continuing MDT 5, 6
Inadequate monitoring, such as failure to screen for G6PD deficiency before dapsone or monitor QT interval with clofazimine, can lead to serious adverse events 5, 6

The World Health Organization recommends considering other granulomatous diseases, such as tuberculosis, sarcoidosis, cutaneous leishmaniasis, and systemic mycoses, in the differential diagnosis of leprosy, as they can present with similar skin lesions and peripheral neuropathy 7

Sarcoidosis manifests with nodular skin lesions and can involve peripheral nerves, but demonstrates negative acid-fast bacilli on skin smears, elevated serum angiotensin-converting enzyme (sensitivity 60%, specificity 70%), and shows non-caseating granulomas on biopsy without nerve predilection 7
Cutaneous leishmaniasis produces ulcerative or nodular lesions that may mimic lepromatous nodules, but lesions are typically painful, lack sensory loss, and demonstrate Leishmania organisms on tissue smear or biopsy rather than acid-fast bacilli 8

Lymphomas (cutaneous T-cell lymphoma) can produce nodular or infiltrative skin lesions mimicking lepromatous leprosy, but histopathology reveals atypical lymphocytes rather than granulomas with acid-fast bacilli 7