Is Perls Prussian Blue Stain for Hemosiderin a Useful Adjunct in the Diagnosis of Vasculitic Neuropathies?

BACKGROUND: Perls Prussian blue stain (PPB) for hemosiderin, a marker of vascular injury is often employed as an adjunct in the diagnosis of vasculitic neuropathies. However, inflammation/vascular injury is also seen in leprosy, immune mediated, paraproteinemic, diabetic neuropathies, etc. The frequency of detection of hemosiderin in these neuropathies and its utility in diagnosis of vasculitis has not been explored. OBJECTIVE: We evaluated 208 peripheral nerve biopsies for hemosiderin deposits by PPB stain in vasculitis (78) and compared with inflammatory/immune neuropathies [leprous neuritis-32, chronic inflammatory demyelinating polyneuropathy (CIDP)-15, paraproteinemic neuropathies (POEMS)-12, diabetic neuropathy-37] and nonimmune neuropathies [Charcot-Marie-Tooth (CMT) disease-15, vitamin B12 deficiency-7, and ischemic neuropathy in aged-12)]. RESULTS: Hemosiderin deposits were most frequent in vasculitis (48.72%) [59.2% in systemic; 43.1% in nonsystemic vasculitides] and enhanced the sensitivity of diagnosis in "probable" vasculitis (34.48%) that lacked transmural inflammation. Hemosiderin was also detected in infectious/immune-mediated neuropathies (leprous neuritis-56%, POEMS-33.3%, diabetes-18.9%) but absent in CMT, B12 deficiency, and ischemic neuropathy. Hemosiderin deposits involved epineurium in vasculitis, compared to endoneurial/perineurial location in leprosy and perineurial in POEMS and diabetic neuropathy. The sensitivity of detection was high in vasculitic neuropathy (49.35%) compared to other inflammatory neuropathies (22.3%) (P < 0.05) with high specificity (77.69% [positive predictive value (PPV)-56.71%; negative predictive value (NPV)-71.6%]. The specificity increased to 89% if leprous neuropathy was excluded, with PPV-77.5% while NPV dropped to 68.5%. CONCLUSION: These findings suggest that PPB stain for detection of hemosiderin is a useful adjunct in diagnosis of vasculitic neuropathy with high specificity but low sensitivity.

Appropriately Selected Nerve in Suspected Leprous Neuropathy Yields High Positive Results for Mycobacterium leprae DNA by Polymerase Chain Reaction Method.

Identification of Mycobacterium leprae DNA by polymerase chain reaction (PCR) is a reliable and an affordable method to confirm leprosy. DNA from 87 nerve samples (61 from paraffin blocks and 26 fresh samples) was extracted. Mycobacterium leprae DNA was amplified by PCR from 80/87 (92%) specimens. Patients were seen over a period of 11 years (2007-2019), and leprosy was diagnosed based on clinical and characteristic histopathology findings. The clinical diagnostic possibilities were as follows: leprous neuropathy in 73/80 (91.3%), mononeuritis multiplex of unknown etiology in four (5.0%), vasculitic neuropathy in two (2.5%), and distal symmetric sensory motor neuropathy in one (1.3%). The biopsied nerves were as follows: superficial radial = 34 (42.6%), dorsal cutaneous branch of ulnar = 19 (23.8%), sural = 18 (22.5%), and superficial peroneal = 9 (11.3%), and corresponding neurological deficits were recorded in 77 (96.3%) cases. The histopathological diagnoses in total group were as follows: (borderline tuberculoid (BT) = 52, tuberculoid (TT) = 8, borderline lepromatous (BL) = 8, borderline borderline (BB) = 3, nonspecific inflammation = 3, healed/fibrosed = 4, and axonopathy = 2). Acid fast bacilli (AFB) was demonstrated in 11 (13.7%) samples. For comparison, 31 clinically and histopathologically defined non-leprous disease control nerves (inherited neuropathy = 20, vasculitis = 8, and nutritional neuropathy = 3) subjected to PCR were negative for M. leprae DNA. In most instances, there are multiple thickened peripheral nerves in suspected cases of leprosy, but neurological deficits pertaining to the thickened nerve are not as widespread. The current findings emphasize the importance of selecting the most appropriate nerve for biopsy to obtain a positive PCR result. We infer that clinical, histopathological, and PCR tests complement each other to help achieve a definitive diagnosis of leprosy particularly in pure neuritic leprosy and in leprous neuropathy with negative skin smears/biopsy.

Evidence for Mycobacterium leprae Drug Resistance in a Large Cohort of Leprous Neuropathy Patients from India.

Resistance to anti-leprosy drugs is on the rise. Several studies have documented resistance to rifampicin, dapsone, and ofloxacin in patients with leprosy. We looked for point mutations within the folP1, rpoB, and gyrA gene regions of the Mycobacterium leprae genome predominantly in the neural form of leprosy. DNA samples from 77 nerve tissue samples were polymerase chain reaction (PCR)-amplified for M leprae DNA and sequenced for drug resistance-determining regions of genes rpoB, folP1, and gyrA. The mean age at presentation and onset was 38.2 ± 13.4 (range 14-71) years and 34.9 ± 12.6 years (range 10-63) years, respectively. The majority had borderline tuberculoid leprosy (53 [68.8%]). Mutations associated with resistance were identified in 6/77 (7.8%) specimens. Mutations seen were those associated with resistance to rifampicin, ofloxacin, and dapsone. All the six patients were drug-naive. The clinical and pathological manifestations in this group did not differ from the drug-sensitive group. This study highlights the occurrence of resistance to the standard multidrug therapy and ofloxacin in leprosy. Among the entire cohort, 1/77 (1.3%) showed resistance to rifampicin, 2/77 (2.6%) to dapsone, and 5/77 (6.4%) to ofloxacin. Six new patients showing infection by mutant strains indicated the emergence of primary resistance. Resistance to ofloxacin could be due to frequent use of quinolones for many bacterial infections. The results of the study indicate the need for development of a robust and strict surveillance system for detecting drug resistance in leprosy in India.

Brain and Spinal Cord Lesions in Leprosy: A Magnetic Resonance Imaging-Based Study.

Neurotropism and infiltration by Mycobacterium leprae of peripheral nerves causing neuropathy are well established, but reports of central nervous system (CNS) damage are exceptional. We report CNS magnetic resonance imaging (MRI) abnormalities of the brain and spinal cord as well as lesions in nerve roots and plexus in leprosy patients. Eight patients aged between 17 and 41 years underwent detailed clinical, histopathological, and MRI evaluation. All had prominent sensory-motor deficits with hypopigmented and hypo/anesthetic skin patches and thickened peripheral nerves. All demonstrated M. Leprae DNA in affected peripheral nerve tissue. All received multidrug therapy (MDT). Two patients had brainstem lesions with enhancing facial nuclei and nerves, and one patient had a lesion in the nucleus ambiguus. Two patients had enhancing spinal cord lesions. Follow-up MRI performed in four cases showed resolution of brainstem and cord lesions after starting on MDT. Thickened brachial and lumbosacral plexus nerves were observed in six and two patients, respectively, which partially resolved on follow-up MRI in the two cases who had reimaging. The site and side of the MRI lesions corresponded with the location and side of neurological deficits. This precise clinico-radiological correlation of proximal lesions could be explained by an immune reaction in the gray matter corresponding to the involved peripheral nerves, retrograde axonal and gray matter changes, or infection of the CNS and plexus by lepra bacilli. Further study of the CNS in patients with leprous neuropathy is needed to establish the exact nature of these CNS MRI findings.

Tangier's disease: An uncommon cause of facial weakness and non-length dependent demyelinating neuropathy.

Tangier disease is an autosomal recessive disorder characterized by an abnormal accumulation of cholesterol esters in various organs secondary to adenotriphosphate binding cassette transporter A-1 (ABCA-1) transporter deficiency and disrupted reverse cholesterol transport. It causes neuropathy in half of the affected individuals. We present the clinical, electrophysiological, and histopathological findings in a middle aged gentleman of Tangier disease who was initially misdiagnosed leprosy and treated with antileprosy drugs. The presence of a demyelinating neuropathy on electrophysiology in a patient with predominant upper limb involvement and facial diplegia should raise the suspicion of Tangier disease. The characteristic lipid profile of Tangier disease was noted in this patient viz. extremely low high density lipoprotein (HDL), elevated triglyceride (TG), and reduced apolipoprotein A1. Estimation of serum lipids should form a part of routine evaluation in order to avoid misdiagnosis.

An uncommon cause of bifacial weakness and non-length-dependent demyelinating neuropathy.

Tangier disease is a rare metabolic disorder that causes neuropathy in half of the affected individuals. We present the clinical, electrophysiological, and histopathological findings in a middle-aged gentleman of Tangier disease who was initially diagnosed as leprosy and treated with antileprosy drugs. The presence of a demyelinating electrophysiology in a patient with predominant upper limb involvement and facial diplegia should raise the suspicion of Tangier disease. Estimation of serum lipids should form a part of routine evaluation in order to avoid misdiagnosis.

Neuropathy in elderly: lessons learnt from nerve biopsy.

OBJECTIVE: To study the utility of nerve biopsy in providing diagnostic, therapeutic or prognostic information that aid in clinical management in elderly subjects with peripheral neuropathy. METHODS: Clinico-pathological data of 100 elderly subjects aged 65 and above with peripheral neuropathy who underwent nerve biopsy in the last decade (2002-2011) was reviewed. RESULTS: The study included 100 subjects (M:F 78:22). Mean age at biopsy and symptom duration was 69.62±4.8 years and 24.17±40.4 months, respectively. The most common pattern of was distal symmetric sensorimotor polyneuropathy (35%), followed by multiple mononeuropathy (29%) and asymmetric sensorimotor neuropathy (15%). The nerve biopsy was 'diagnostic' in 24%, (definite vasculitis in 12, leprosy in 10 and acute inflammatory demyelinating polyradiculoneuropathy in 2) and proved 'essential' or 'helpful' in therapeutic management in 81% subjects. In 60 (60%) patients, where a pre-biopsy aetiological diagnosis could be arrived at based on the available data, nerve biopsy confirmed the diagnosis in 29 of 60 (48.3%), and offered a new diagnosis in 25 (41.7%). A higher yield of biopsy was noted in subjects with asymmetric/multiple mononeuropathy compared with symmetric neuropathies (32.7% versus 17.7%). In 40 (40%) patients without a pre-biopsy aetiological diagnosis, nerve biopsy was 'essential' in 7 of 40 (17.5%) as it provided a definitive diagnosis (definite vasculitis: 5, leprosy: 2), and 'helpful' in 21 of 40 (52.5%) (ischaemic neuropathy: 10, possible vasculitis: 9, probable vasculitis: 2). CONCLUSION: Nerve biopsy aided in the detection of potentially treatable disorders and influenced patient management in a significant proportion of elderly subjects with peripheral neuropathy (81%), particularly in subset with undiagnosed neuropathies confirming that it's a useful tool in diagnosis of neuropathy in the elderly. With minor differences, the aetiological profile in our biopsied neuropathic elderly subjects may reflect the findings in other similar cohorts.

Pseudoathetosis in a patient with leprosy.

A 35-year-old man with borderline tuberculoid leprosy developed Type I lepra reaction 12 days after anti-leprosy treatment. There was acute worsening of neuropathic symptoms and skin lesions. He developed severe sensory ataxia and pseudoathetosis resulting in marked disability. His symptoms significantly improved on corticosteroid therapy.