Authors: Dr Elise Ouedraogo, Dermatology Registrar, University Paris VI, Paris, France; Prof Pierre Couppie, Dermatologist, University of the Antilles and Guyane, Cayenne, French Guiana. DermNet NZ Editor in Chief: Adjunct A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand. Copy edited by Maria McGivern/Gus Mitchell. March 2017.
Leprosy is a bacterial infectious disease that mainly affects people in developing countries, including Brazil, Bangladesh, India, the Democratic Republic of Congo, and Nigeria.
The type 1 lepra reaction is a delayed type of hypersensitivity to M. leprae antigens. It is also called a lepra 1 reaction.
The lepra 1 reaction is unpredictable. It occurs in patients with borderline disease; that is, the transition between tuberculoid leprosy and lepromatous leprosy.
The classification of borderline leprosy includes:
Type 1 lepra reactions typically affect the skin and nerves, and there are no systemic symptoms. The reaction is classified as mild or severe.
Skin signs of type 1 lepra reaction include:
Nerve involvement in type 1 lepra reaction, and:
A mild type 1 lepra reaction is characterised by a few inflamed plaques and no nerve impairment. A severe type 1 lepra reaction is characterised by many inflamed plaques and nerve impairment.
A type 1 lepra reaction is clinically suspected in a patient with borderline leprosy that develops symptoms within a few months of starting treatment.
There are no routine laboratory tests. A skin biopsy may reveal:
There is no increase of polymorphonuclear neutrophils in the patient's blood count or a change in C-reactive protein (CRP) levels. Type 1 lepra reactions have been associated with elevated levels of serum chemokine 10.
A mild lepra 1 reaction requires supportive care. This involves:
A severe type 1 lepra reaction with nerve impairment requires prompt treatment.
The natural course of an untreated type 1 lepra reaction is for it to persist for several months.
A type 2 lepra reaction is characterised by an acute immune complex vasculitis affecting the skin and other organs. It is poorly understood. It is also called lepra 2 reaction or erythema nodosum leprosum.
The type 2 lepra reaction occurs in patients with:
Type 2 lepra reaction is commonly associated with:
The clinical features of lepra 2 reactions depend on its severity and which organs are affected.
In type 2 lepra reaction, the skin may show:
Other clinical features of type 2 lepra reaction may include:
A type 2 lepra reaction is clinically suspected if a patient with lepromatous leprosy or borderline lepromatous leprosy complains of fever and fatigue and has multiple painful red skin nodules, whether or not they have received treatment.
Blood tests show high inflammatory markers. These include:
Pathology is essential to confirm type 2 lepra reaction. A biopsy of a new red nodule less than 24 hours old shows:
Treatment depends on the severity of the type 2 lepra reaction as assessed clinically and supported by laboratory tests. A mild cutaneous reaction without other organ impairment can be managed by supportive care. This includes:
Treatment for severe type 2 lepra reactions may include:
Without treatment, type 2 lepra reactions continue for about 2 weeks then settle down. Recurrences are frequent.
Untreated type 2 lepra reactions can result in renal failure requiring dialysis, liver failure requiring transplantation, blindness, and/or long-term inflammation of the testicles.
Lucio phenomenon is a very rare, acute, and severe complication of longstanding and untreated lepromatous leprosy. It may be life-threatening.
Lucio phenomenon is treated intensively with systemic steroids.
Scollard D, Stryjewska B. Epidemiology, microbiology, clinical manifestations, and diagnosis of leprosy. UpToDate. Updated 1 December 2016. Available at: www.uptodate.com/contents/epidemiology-microbiology-clinical-manifestations-and-diagnosis-of-leprosy (accessed March 2017).
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