Lupus Peripheral Neuropathy Masquerading as Leprosy

Sir, A 12-year-old boy presented with progressive clawing of the fingers of the right hand, associated with reduced pain and temperature sensation for the last two years. Later, he developed moderate to high-grade fever over the last 2 months. He was being treated for leprosy with a multi-drug therapy regimen, including dapsone, clofazimine, and rifampicin, elsewhere, but his symptoms continued to worsen. The slit skin smear for Mycobacterium leprae, prior to starting muti-drug therapy (MDT), was negative. Examination revealed severe pallor, alopecia, and a hypopigmented macule over the left cheek with intact sensation. Neurological examination revealed right-hand palmar atrophy and clawing of the fingers [Figure 1a and b]. No peripheral nerve thickening, beading, or tenderness was noted. Weakness of right-sided thumb adduction (positive Froment sign), right abductor digiti minima, flexor digiti minima brevis, opponents digiti minima, and palmar and dorsal interossei was noted. Additionally, the right thumb abduction, flexion, and opposition were weak. The pain and temperature sensation were impaired over the right ulnar nerve innervation, while touch, pressure, and proprioception were intact. Laboratory investigations revealed reduced hemoglobin, normal white cell count, low platelet count, increased erythrocyte sedimentation rate, and normal C-reactive protein. Peripheral blood smear showed evidence of hemolysis, lactate dehydrogenase level was elevated and direct Coomb’s test was positive. Both C3 and C4 complement levels were low. The anti-nuclear antibody profile was positive for anti-SmD1 and dsDNA antibodies. Nerve conduction study revealed reduced compound muscle action potential (CMAP) amplitude in the right median nerve with increased latency and reduced velocity, an inexcitable right ulnar nerve, reduced CMAP amplitude with increased distal latency and reduced velocity in the right median nerve, and reduced conduction velocity in the bilateral peroneal and left tibial nerves. Minimal latency of the F-waves was prolonged in the right median, bilateral tibial, and bilateral peroneal nerves. The F-wave was not elicitable in the right ulnar nerve. The electrophysiological study was suggestive of asymmetric demyelinating motor neuropathy [Figure 1c].Figure 1: Photograph of the right hand shows atrophy of the thenar and hypothenar muscles muscles and clawing of the fourth and fifth digits (a and b). Nerve conduction study (c) shows reduced CMAP amplitude in the right median nerve with increased latency and reduced velocity, an inexcitable right ulnar nerve, increased distal latency with reduced CMAP amplitude and velocity in the right median nerve, and reduced conduction velocity in bilateral peroneal and left tibial nerves. Minimal latency of the F-waves was prolonged in the right median, bilateral tibial, and bilateral peroneal nerves. The F-wave was not elicitable in the right ulnar nerveThe diagnosis of systemic lupus erythematosis (SLE) with peripheral nerve involvement and hemolytic anemia was made based on the clinical features and laboratory parameters.[1] Multidrug therapy for leprosy was stopped, and he received pulse methylprednisolone 30 mg/kg for 3 days, followed by oral prednisolone. After an ophthalmological evaluation, hydroxychloroquine (HCQ) was added. He received cyclophosphamide 500 mg/m² for six doses, 4 weeks apart. Rehabilitative measures for the claw hand were initiated, and he is doing well at the last follow-up. The exact incidence of peripheral neuropathy in childhood lupus is unknown. While many reports of leprosy mimicking SLE have been documented, to our knowledge, this is the first report of SLE masquerading as leprosy in children. In one of the largest cohorts from Canada, which included 91 cases of childhood SLE, only 2 patients had peripheral neuropathy.[2] Similarly, in a report from Israel involving a cohort of 35 children, only 4 children had peripheral neuropathy.[3] Differentiating lupus-associated peripheral neuropathy from neurotic leprosy can be challenging. It is necessary to perform a complete blood count, erythrocyte sedimentation rate, C-reactive protein, direct Coombs test, antinuclear antibody (ANA) profile, C3 and C4 levels, and antiphospholipid antibodies testing when features such as fever, hematological involvement, or involvement of other systems are present, which cannot be explained by leprosy alone. Additionally, this case highlights that peripheral neuropathy alone may be the presenting feature of lupus, with systemic features appearing much later in the course of the illness. Treatment of peripheral neuropathy in SLE is guided by observational studies due to lack of randomized trials. Glucocorticoids, cyclophosphamide, azathioprine, plasmapheresis, rituximab, mycophenolate mofetil, and intravenous immunoglobulin are the commonly used immunosuppressive agents. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

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