Diagnostic value of markers of muscle degeneration in sporadic inclusion body myositis

Sporadic inclusion body myositis (s-IBM) is characterized histologically by the association of concomitant inflammatory and degenerative processes. We evaluated the sensitivity and specificity of different markers of the degenerative process in order to refine the histological diagnosis. We performed an immunohistochemical study with antibodies directed against ubiquitin, amyloid-beta precursor protein (AbetaPP), amyloid-beta (Abeta), SMI-31, SMI-310, Tar-DNA binding protein-43 (TDP-43) and p62 on s-IBM and control muscle biopsies. Based on conventional stains 36 patients with characteristic clinical features of s-IBM were subclassified as presumed definite s-IBM (d s-IBM, n = 17) or possible s-IBM (p s-IBM, n = 19) according to the presence or absence of vacuolated muscle fibers. Immunohistochemically, TDP-43 and p62 were the most sensitive markers, accumulating in all d s-IBM and in 31% and 37%, respectively, of the p s-IBM cases and thus enabling reclassification of these cases as d s-IBM. We recommend using TDP-43 and p62 antibodies in the histological diagnosis workup of s-IBM. The specificity of these markers has to be further validated in prospective series.

Non-anti-MAG DADS neuropathy as a variant of CIDP: clinical, electrophysiological, laboratory features and response to treatment in 10 cases

BACKGROUND AND PURPOSE

Some patients within the spectrum of chronic inflammatory demyelinating polyradiculoneuropathies (CIDP) have distal acquired demyelinating symmetric (DADS) neuropathy, usually associated with anti-myelin-associated-glycoprotein (MAG) IgM monoclonal gammopathy. The aim of this retrospective study was to investigate patients with DADS neuropathy without anti-MAG antibodies, and study their response to immunotherapy.

METHODS

Patients were selected on the basis of (i) 'Definite CIDP' according to the EFNS/PNS Guideline criteria, (ii) The presence of disproportionately prolonged motor latencies resulting in a terminal latency index (TLI) ≤ 0.25 in at least two motor nerves and (iii) The absence of anti-MAG antibodies on ELISA. Response to immunotherapy was defined as persistent improvement by at least one point on the INCAT disability score.

RESULTS

Data from 146 CIDP patients were analysed, and 10 patients were included. Six had clinically pure sensory neuropathy, and four had sensorimotor neuropathy. Ataxia was present in nine patients, generalized areflexia in seven and postural tremor in two. Five of the 10 patients had abnormal sensory potentials only in the upper limbs. An associated condition was found in nine patients: two chronic lymphocytic leukaemias, four IgG monoclonal gammopathies (one associated with non-Hodgkin's lymphoma) and two IgM monoclonal gammopathies of unknown significance. Patients were mostly improved with intravenous immunoglobulin (IVIg), corticosteroids, plasma exchanges, or a combination thereof.

CONCLUSION

DADS neuropathy without anti-MAG antibodies is more likely to be considered a variant of CIDP. In addition, such patients should be systematically investigated for an associated haematological or immunological condition.

Hepatitis C virus-associated polyarteritis nodosa

OBJECTIVE

To analyze the main characteristics and outcome of polyarteritis nodosa (PAN)-type vasculitis associated with hepatitis C virus (HCV).

METHODS

We reported the characteristics and outcome of 31 patients chronically infected with HCV who satisfied the American College of Rheumatology and Chapel Hill criteria for PAN, seen between 1990 and 2009 in a university center.

RESULTS

Among a cohort of 161 patients with HCV-related vasculitis, 31 (19.3%) were diagnosed as having PAN. The median age was 64.5 years (interquartile range 49.5-70.5 years), with 54.8% women. Compared with HCV-associated mixed cryoglobulinemia (HCV-MC) vasculitis, HCV-PAN displayed a more severe and acute clinical presentation with more frequent fever and weight loss (P < 0.0001), severe hypertension (P = 0.0006), gastrointestinal tract involvement (P < 0.0001), severe acute sensory-motor multifocal mononeuropathy (P < 0.0001), kidney and liver microaneurysms (P = 0.002), and increased C-reactive protein level (P < 0.0001). Complete clinical remission of vasculitis was achieved in 79.3% of HCV-PAN patients compared to 57.5% of HCV-MC patients (P = 0.05). In multivariate analysis, skin involvement (odds ratio [OR] 2.81, 95% confidence interval [95% CI] 1.27-6.33) and PAN-type vasculitis (OR 3.01, 95% CI 1.16-8.96) were independently associated with a complete clinical response of HCV vasculitis. A glomerular filtration rate <70 ml/minute (OR 0.54, 95% CI 0.24-1.21) was negatively associated with a complete clinical response of HCV vasculitis. The 5-year survival rate was 86% in the entire cohort, regardless of the vasculitis type.

CONCLUSION

HCV-PAN accounts for 19.3% of our cohort of HCV vasculitis. HCV-PAN displays a more severe and acute clinical presentation and a higher rate of clinical remission.

Electron microscopy in myofibrillar myopathies reveals clues to the mutated gene

We studied the ultrastructural characteristics in patients with myofibrillar myopathy (MFM) and differentiated between MFM-subtypes using electron microscopic (EM) findings. The ultrastructural findings in 19 patients with different genetically proven MFMs (9 desmin, 5 alphaB-crystallin, 3 ZASP, 2 myotilin) were analyzed. In one ZASPopathy, we additionally performed an immunoEM study, using antibodies against desmin, alphaB-crystallin, ZASP and myotilin. The ultrastructural findings in desminopathies and alphaB-crystallinopathies were very similar and consisted of electrondense granulofilamentous accumulations and sandwich formations. They differed in the obvious presence of early apoptotic nuclear changes in alphaB-crystallinopathies. ZASPopathies were characterized by filamentous bundles (labeled with the myotilin antibody on immunoEM), and floccular accumulations of thin filamentous material. Tubulofilamentous inclusions in sarcoplasm and myonuclei in combination with filamentous bundles were characteristic for myotilinopathies. We conclude that MFMs ultrastructural findings can direct diagnostic efforts towards the causal gene mutated, and that EM should be included in the diagnostic workup of MFMs.

Neuropathy in lymphoma: a relationship between the pattern of neuropathy, type of lymphoma and prognosis?

BACKGROUND

Neuropathies associated with lymphoma (NAL) are rare and present a great clinical heterogeneity, making them difficult to diagnose and worsening their prognosis.

OBJECTIVES

(1) To report the different patterns of NAL and discuss the mechanisms encountered; (2) to determine the relationship between a given type of lymphoma and a specific type of neuropathy; and (3) to assess the prognosis of NAL.

METHODS

Among 150 patients with lymphoma and neuropathy, we selected 26 in whom the neuropathy was not related to drug induced or IgM-antimyelin associated glycoprotein neuropathies. The pattern of neuropathy was defined in terms of its clinical and electrophysiological features. Neurological improvement, haematological remission and occurrence of death were taken into account to determine the prognosis.

RESULTS

13 patients (50%) had a demyelinating polyneuropathy (PNP), seven (27%) had a radiculopathy linked to proximal root tumoral infiltration and six (23%) had an axonal multiple mononeuropathy (MM) related to distal lymphomatous infiltration or to paraneoplastic microvasculitis. Hodgkin's lymphoma was only associated with demyelinating PNP. High grade B cell lymphoma was strongly associated with radiculopathy. Neurological improvement was observed in 69% of patients with demyelinating PNP, 29% with radiculopathy and 50% with MM. Haematological remission was observed in 46% of patients with demyelinating PNP, 29% with radiculopathy and 83% with MM.

CONCLUSIONS

Demyelinating PNP, the most frequently observed neuropathy in this study, had the best neurological prognosis. Chemotherapy combined with immune mediated treatment was the most effective treatment in this group. Identifying the type and mechanism of NAL is crucial in order to define the therapeutic strategy and improve the prognosis.

Complete fatty degeneration of lumbar erector spinae muscles caused by a primary dysferlinopathy

Magnetic resonance imaging of the thoracolumbar spine showed complete fatty degeneration of the lumbar erector spinae muscles in a woman who had complained of chronic lower back pain for 5 years and of progressive weakness of the lower limbs for 1 year. Neuromuscular examination of the lower limbs showed no obvious anomaly, and there was no camptocormia. Serum creatine kinase levels were increased (six- to ninefold); electrodiagnostic examination revealed no activity at rest or during effort in the erector spinae muscles and was normal in proximal and distal muscles of the limbs. Muscle computed tomography revealed mild fatty degeneration of thigh and gastrocnemius muscles, and histopathology of the deltoid muscle showed dystrophic features and complete lack of dysferlin. Molecular analysis identified a homozygous disease-causing mutation in the gene encoding dysferlin. Because there were no similar cases in the family, the final diagnosis was sporadic limb-girdle muscular dystrophy type 2B. Overall, this case report shows that the lumbar and lower thoracic of erector spinae muscles may display complete fatty degeneration without the occurrence of camptocormia, with primary dysferlin deficiency as a possible cause.

Intravenous immunoglobulin as short- and long-term therapy of multifocal motor neuropathy: a retrospective study of response to IVIg and of its predictive criteria in 40 patients

OBJECTIVE

To document short-term and long-term responses to a single type of intravenous immunoglobulin (IVIg) in a large cohort of patients with multifocal motor neuropathy (MMN).

METHODS

A retrospective study was conducted in 40 patients with MMN included on ENMC Workshop criteria, and treated with periodic IVIg infusions between 1995 and 2003. The short-term response was defined as improvement of at least 1 point on the MRC score in at least two affected muscles at 6 months. The population comprised 22 treatment-naïve patients (who had never received IVIg before inclusion), and 18 previously treated patients. For the long-term evaluation (>6 months), the patients were classified into three groups according to the dependency or not on periodic IVIg. In addition, changes in conduction block (CB) and predictive criteria for response to IVIg were explored.

RESULTS

The MRC score significantly improved (p<0.0001) in 14 (70%; 95% CI 0.46 to 0.88) of the 20 treatment-naïve patients (missing data for 2 patients). None of the predictive criteria studied were found to be significant. At the end of follow-up (mean of 2.2+/-2.0 years), only 8 of the 40 patients (22%) had significant remission, whereas 25 patients (68%) were dependent on periodic IVIg infusions. The number of CBs decreased or remained unchanged in 12 treatment-naïve patients and increased in 2 such patients.

CONCLUSIONS

This study confirmed a significantly high short-term response to IVIg of patients with MMN, but showed contrasted results in long-term follow-up. No predictive factors for response to IVIg were found.