Comparative Analysis Of Clinicopathology Data Of59IIM Patients

Objective: Idiopathic inflammatory myopathy (IIM) is a heterogeneousgroup of acquired autoimmune muscle disorders, which includedermatomyositis (DM), polymyositis (PM), and inclusion body myositis (IBM)in a narrow sense. A broad IIM also include eosinophilic fasciitis (EF), focalmuscle inflammation (FM) and granulomatous myositis (GM). The mainclinical features include symmetric proximal muscle weakness with slowprogresses, myalgia, muscle grip pain, and typical skin rashes in DM.Libratory testing demonstrates elevated serum creatine kinase (CK),erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP).Electromyography (EMG) shows classic pattern of muscular impairment. Thetypical histopathologic findings of muscle biopsy are inflammatory cellsinfiltration, degeneration, necrosis, regeneration of muscle fibers,characteristic perifascicular atrophy of DM, typical or atypical rimmedvacuoles in muscle fibers of IBM, and there are obvious connective tissueproliferation and lipid droplets in muscle fibers over a long course of disease.However, in clinical practice work, some IIM patients who present withtypical clinical manifestations have no apparent inflammatory infiltrates ofIIM, even when the muscle biopsy is performed at the site of myalgia.Recently some studies found that vascular injury is involved in thepathogenesis of IIM, which is primary event in pathogenesy of DM. Vascularinjury can lead to hypoxia of local muscle tissue, degeneration and necrosis ofmuscle fibers, contributed to muscle weakness and fatiguability. Thisvascular damage is present in the skin, fascia and muscle tissue and can occurbefore the inflammatory infiltration in muscle tissues. It indicates that biopsyincluding muscle, skin, and fascia can probability of the diagnosis and is veryuseful for clinical work. The subject of this study was to analyzed the clinicopathology of59cases, including DM, PM, and undeterminedinflammatory myopathy (IM) patients, especially those without obviousinflammatory cell infiltrates, and to investigate the role of skin and fasciabiopsy in the diagnosis of IIM, in order to improve early diagnosis of IIM atthe cellular level.Methods: We performed a retrospective study of59IIM patients. Collectthe clinical and pathological data of the patients who had been admitted to theneuromuscular department of Third Hospital of Hebei Medical Universityform2005to2012.59patients were selected according to the B/P standard,including25patients with diagnosed DM,5patients with diagnosed PM, and29patients with probable IM. Remained11cases were excluded due to lack ofclinical data, steroid therapy before biopsy, or specimens from other hospitals.All of these patients were performed open muscle biopsy (including muscle,fascia, and skin) after signing informed consent. All specimens were verticallyfixed with tragacanth, sufficiently cooled down in isopentane or liquidnitrogen, cut into slices of7μm in thickness using constant cold slicer, andfinally series of histochemical staining. Analyze the pathologicalcharacteristics of the3groups of patients under the light microscope combinedwith clinical data.Results:1The main clinical characteristics of IIM:①symmetric muscle weakness,myalgia, the most common seen is muscle weakness of proximal limbs(83.1%); neck muscle and shoulder girdle muscles were also frequentlyinvolved, dysphagia is present in small number of cases (11.9%).②Skin rashand cancer are frequently developed in DM patients. Severe JDM case maydevelop extensive calcinosis. Other system involvement such as interstitiallung disease (ILD), arthralgia, rheumatoid arthritis often occurred③CK inmost cases is increased. This is most significant in PM and can be up to100times of normal value average. ESR was elevated in82.1%of cases, whichcan be up to5.75times of normal; CRP was elevated with the incidence of55.8%, and the highest is up to10.89times of normal.④EMG examination displayed myogenic findings in70.5%of cases, others were neuropathic,mixed, or normal.2The main pathology findings of IIM:①Inflammatory infiltration inmuscle tissue is predominantly in perimysium or around small blood vesslesof DM, while it is predominant in endomysial and around blood vessles of PM.②Perifascicular atrophy is characteristic for DM. The degeneration, necrosis,regeneration is more significant in PM than in DM and probable IIM, anddegeneration is most frequently seen. Connective tissue characteristic is mostsignificant in PM.③Vacuoles in muscle fibers which are resulted fromischemia in early disease, and due to lipid deposition in advanced disease.④Inflammatory cells infiltration is often around small blood vessel in dermis ofskin tissue.⑤Inflammatory cells infiltration in fascia is frequently seen inIIM.⑥There are no evident inflammatory infiltration or perifascicularatrophy in muscle of some DM and probable IIM patients, only presentingwith inflammatory infiltration in the fascia or small blood vessel of DM.Conclusions:1The patients who present with symmetric proximal muscle weakness oflimbs, myalgia, or characteristic rash should be performed liboratoryexamination and EMG actively. If the blood CK is elevated, or EMG revealedneuropathy or myopathy, we should highly suspected the diagnosis may beinflammatory myopathy. The development of pulmonary fibrosis andmalignancy should be given attention. Biopsy of muscle, skin, and fascia ishelpful for diagnosis.2Inflammatory cells infiltration is important evidence for diagnosis of IIM.For EF patients, there may be no positive findings on muscle biopsy, withinflammatory infiltration in fascia, which is important for final diagnosis.Muscle, skin, and fascia tissue can simultaneously be involved withinflammatory cells infiltration in IIM, so biopsy of muscle, skin, fascia canimprove the diagnosis rate.3We should perform immunopathogenesis study about monoclonalantibody (MHC-Ⅰ, CD4, CD8, CD20, CD68) actively on the basis of histochemical staining. Examination of these markers can provide moreinformation for typing diagnosis of IIM.