Leprosy is a disease, which is more common in endemics areas and developing countries. Because of increase travel in today’s world, it is possible that we may come across with leprosy patient in non-endemic areas. It is important to be updated about different manifestation of leprosy in order to avoid unnecessary diagnostic tests and to start proper and early treatment.
Exact pathogenesis of joint involvement in leprosy is still not fully elucidated. Lepra reactions (Graham et al. 2010; Bhat and Prakash 2012; Wakhlu and Agarwal 2010) (Types I and II lepra reaction), and direct infiltration (Wakhlu and Agarwal 2010) of the synovium by mycobacterium leprea are thought to be the underlying pathogenesis mechanisms for joint involvement. Peripheral sensory neuropathy (Wakhlu and Agarwal 2010) can also lead to Charcot’s neuropathy.
There are two types of immunologic reactions to mycobacterium leprae antigens. These immunologic reactions can occur before, during or after the treatment of leprosy.
Type 1 Lepra (Graham et al. 2010; Bhat and Prakash 2012) reaction is a delayed hypersensitivity reaction. It is cell mediated immune response to M. leprae antigenic determinants and is characterized by acute inflammation of pre-existing skin lesions or by the appearance of new lesions and/or neuritis. Systemic involvement does not occur in type 1 reation.
Type 2 lepra (Graham et al. 2010; Bhat and Prakash 2012) reaction also termed as Erythema nodosum leprosum (ENL) is an immune complex mediated (type 3 hypersensitivity) response to M.leprae antigenic determinants. It results in severe painful skin lesion, nerve damage, fever and systemic manifestation. Systemic involvement can lead to arthritis, dactyltis, orchtitis, uveitis, lymphadenitis, glomerulonephritis, protienuria and hepatitis. It occurs mostly during the fist year of leprosy treatment. Recurrence of type 2 reaction is also common during treatment.
Chauhan et al (Wakhlu and Agarwal 2010) classify the arthritis in leprosy into the following groups: (1) Charcot’s arthropathy secondary to peripheral sensory neuropathy; (2) swollen hands and feet syndrome; (3) acute polyarthritis of lepra reaction; and (4) chronic arthritis from direct infiltration of the synovium by lepra bacilli.
Shiva PRASAD (Prasad et al. 2012) and his team conducted retrospective case series study of leprosy patients. Forty-four cases with leprosy were identified. Musculoskeletal manifestations included arthritis (n = 22), swollen hands and feet syndrome (n = 11), tenosynovitis (n = 9), painful swollen feet (n = 9), arthralgia (n = 7) and vasculitis (n = 1). Arthritis and tenosynovitis were part of spontaneous onset lepra reaction in 28 cases.
S L Atkin et al. (Atkin et al. 1990) conducted a study in seventy-seven patients with leprosy. Study showed that ten patients had generalized enthesitis and twenty patients had leprosy with manifestations of arthritis.
Another study, conducted by S L Atkin (Atkin et al. 1987) in patients with leprosy in Papua New Guinea, showed that 31 patients out of 55 had peripheral symmetrical inflammatory arthritis.
Hence it is important to include leprosy in list of possible differential diagnosis of arthritis, mainly in those countries where leprosy is prevalent or those patients who travelled from endemic areas.
Our patient’s presentation with peculiar skin lesion combined with acute polyarthritis leads to diagnosis of leprosy.
Our patient presented with an acute onset of symmetrical polyarthritis and high-grade fever. High inflammatory markers, leukocytosis (Legendre et al. 2012) negative blood and urine cultures are supporting evidence for type 2 lepra reaction. Acute arthritis as well as enthesitis and tenosynovitis improved within a week after initiation of treatment.
Sometime, it is difficult to differentiate symmetrical polyarthritis due to leprosy from rheumatoid arthritis as in our patient. This question was entertained upon initial presentation of our patient with symmetrical polyarthritis. Absence of rheumatoid nodule, extra articular manifestation, patient being male, good response to anti leprosy treatment, and absence of Rheumatoid factor and anti-ccp are the clinical distinguishing features from rheumatoid arthritis in our patient.
At presentation patient also had acute renal impairment, which improved with hydration. Wide variety of renal involvement (Ahsan et al. 1995; Aggarwal et al. 2004) occurs in leprosy. Glomerular and interstitial lesions both can happen in leprosy. Glomerulonephritis, acute interstitial nephritis, tubulointerstitial nephritis, acute tubular necrosis and amyloidosis are important renal manifestation of leprosy.
Clinical feature of glomerulonephritis due to leprosy consist of asymptomatic hematuria and proteinuria. In some cases patient can also present with nephritic clinical picture. Immune complex mediated glomerulonephritis is the most common form of glomerulonephritis. ENL type 2 lepra (Ahsan et al. 1995; Aggarwal et al. 2004; Singhal et al. 1977) reaction is immune complex type 3 hypersensitivity reaction which can lead to immune complex mediated glomerulonephritis in leprosy.
Our patient had mild acute renal impairment with transient hematuria and proteinuria. In the presence of systemic manifestation, transient renal impairment was most likely secondary to type 2 lepra reaction.
The other interesting part in our case was second presentation, which was acute in onset. In spite on multidrug treatment and low dose steroid, patient developed this acute presentation. Patient developed new skin lesions, fever and polyarthritis. Laboratory investigation showed leukocytosis and raised liver enzyme. Question was raised whether patient has recurrence of leprosy disease or simply a lepra reaction. Possibility of drug induced liver injury was also entertained. It is interesting to note that recurrence (Graham et al. 2010; Bhat and Prakash 2012) of type 2 lepra can happen while patient on treatment. Type 2-lepra reaction can present with all these systemic manifestation including raised liver enzymes. Patient was managed as having type 2 lepra reaction and responded well.