Differential diagnosis of idiopathic inflammatory myopathies

Co-existence of Juvenile dermatomyositis and psoriasis vulgaris with fungal infection: A case report and literature review

INTRODUCTION

The incidence rate of psoriasis vulgaris (PSV) coexisting with Juvenile dermatomyositis (JDM) is low. Through our thorough literature search, we found that PSV arising on JDM with superficial fungal infection of facial skin is rarely reported. So, we hereby, report a case of combination of the above three diseases. Meanwhile, we also reviewed the previous literatures aiming at the related basis, clinical manifestation, diagnosis, and treatment of the diseases. Interestingly, of all cases, this case is the only one in which the symptom of muscle weakness preceded the appearance of rash.

CASE PRESENTATION

A 21-year-old man diagnosed with JDM 6 years ago came to our inpatient department due to the appearance of new rash. Skin examination showed some sharply demarcated scaly plaques over the head, neck, torso, and bilateral upper limbs with pruritus and scaling. Histological examination and typical clinical manifestation confirmed the diagnosis of PSV for his new rash. Family history was negative for JDM and PSV. The clear erythema located on his face revealed the existence of superficial fungal infection with the help of fungal fluorescence microscopy. He had marked improvement of his symptoms with the treatment given at our department. In the past 3 months, the patient has been on regular follow-up at our outpatient department, and his condition is stable at present.

DISCUSSION

This paper presents a case of PSV arising on JDM coexisting with superficial fungal infection on the face hoping that this will help clinicians in the better diagnosis of the diseases during literature search.

Clinical and laboratory features distinguishing juvenile polymyositis and muscular dystrophy

OBJECTIVE

To differentiate juvenile polymyositis (PM) and muscular dystrophy, both of which may present with chronic muscle weakness and inflammation.

METHODS

We studied 39 patients with probable or definite juvenile PM and 9 patients with muscular dystrophies who were initially misdiagnosed as having juvenile PM. Differences in demographic, clinical, and laboratory results; outcomes; and treatment responses were evaluated by Fisher's exact and rank sum tests. Random forests classification analysis and logistic regression were performed to examine significant differences in multivariable models.

RESULTS

Clinical features and serum muscle enzyme levels were similar between juvenile PM and dystrophy patients, except 89% of dystrophy patients had muscle atrophy compared with 46% of juvenile PM patients. Dystrophy patients had a longer delay to diagnosis (median 12 versus 4 months) and were less frequently hospitalized than juvenile PM patients (22% versus 74%). No dystrophy patients, but 54% of juvenile PM patients, had a myositis autoantibody. Dystrophy patients more frequently had myopathic features on muscle biopsy, including diffuse variation of myofiber size, fiber hypertrophy, and myofiber fibrosis (44-100% versus 8-53%). Juvenile PM patients more frequently had complex repetitive discharges on electromyography and a complete response to treatment with prednisone or other immunosuppressive agents than dystrophy patients (44% versus 0%). Random forests analysis revealed that the most important features in distinguishing juvenile PM from dystrophies were myositis autoantibodies, clinical muscle atrophy, and myofiber size variation on biopsy. Logistic regression confirmed muscle atrophy, myofiber fibrosis, and hospitalization as significant predictors.

CONCLUSION

Muscular dystrophy can present similarly to juvenile PM. Selected clinical and laboratory features are helpful in combination in distinguishing these conditions.

Noninflammatory myopathies

The noninflammatory myopathies are a diverse group of diseases, some of which may mimic the autoimmune-mediated idiopathic inflammatory myopathies in their clinical presentation. They include certain metabolic, toxic, and infectious myopathies, as well as muscular dystrophies. In addition to muscle weakness, these forms of myopathy may present with exercise intolerance and muscle pain. Special testing techniques are often required to establish the diagnosis. This review focuses on those noninflammatory myopathies that should be included in the differential diagnosis of idiopathic inflammatory myopathy.

[What is new in 2010 for electron microscopy in surgical pathology?]

Différentes méthodes complémentaires permettant d’optimiser le diagnostic et le pronostic des lésions observées dans un laboratoire d’anatomopathologie ont permis, ces dernières années, d’améliorer considérablement l’offre de soins aux patients. Ces méthodes correspondent essentiellement aux techniques d’immuno-histochimie et de biologie moléculaire. La place d’une autre technique autrefois largement utilisée en anatomopathologie, la microscopie électronique (ME), est à l’inverse de plus en plus restreinte. La ME est une méthode longue, difficile, onéreuse, nécessitant un personnel hautement qualifié. Elle est de moins en moins implantée dans un laboratoire de pathologie et devient surtout réservée à des centres universitaires et de recherche. Toutefois, la ME reste un outil indispensable pour le pathologiste. En effet, elle permet parfois de confirmer, et plus exceptionnellement de poser, le diagnostic de certaines lésions tissulaires et cellulaires observées en pathologie humaine. La ME est aussi d’un apport très important pour la compréhension de la physiopathologie de certaines maladies humaines émergentes, notamment d’origine infectieuse. Nous abordons dans cette revue les principales indications actuelles de la ME, en insistant sur certains domaines de la pathologie humaine, comme les maladies infectieuses et certaines tumeurs.

Review article: the gastrointestinal complications of myositis

BACKGROUND

The inflammatory myopathies are a group of acquired diseases characterized by a proximal myopathy caused by an inflammatory infiltrate of the skeletal muscle. The three major diseases are dermatomyositis, polymyositis and inclusion body myositis.

AIMS

To review the gastrointestinal manifestations of myositis.

METHODS

Over 110 articles in the English literature were reviewed.

RESULTS

Dysphagia to solids and liquids occurs in patients with myositis. The pharyngo-oesophageal muscle tone is lost and therefore patients develop nasal speech, hoarseness, nasal regurgitation and aspiration pneumonia. There is tongue weakness, flaccid vocal cords, poor palatal motion and pooling of secretions in the distended hypopharynx. Proximal oesophageal skeletal muscle dysfunction is demonstrated by manometry with low amplitude/absent pharyngeal contractions and decreased upper oesophageal sphincter pressures. Patients exhibit markedly elevated creatine kinase and lactate dehydrogenase levels consistent with muscle injury. Myositis can be associated with inflammatory bowel disease, coeliac disease and interferon treatment of hepatitis C. Corticosteroids and other immunosuppressive drugs comprise the mainstay of treatment. Inclusion body myositis responds poorly to these agents and therefore a myotomy is usually indicated.

CONCLUSION

Myositis mainly involves the skeletal muscles in the upper oesophagus with dysphagia, along with proximal muscle weakness.

Idiopathic inflammatory myopathy: treatment options

Idiopathic inflammatory myopathy (IIM) comprises a group of rare disorders in which there is an immune-mediated attack on skeletal muscle, the consequence of which is muscle damage and weakness in the patient. As in other inflammatory diseases, the general approach to therapy is use of immunosuppressive agents. Many options exist for IIM treatment, but therapeutic approaches are based mostly on empirical evidence and small studies, many of which are uncontrolled. Recently, new agents have been designed to target specific components of the immune response, and they offer hope for more effective or safer IIM therapy.

Acute myositis in a patient with systemic sclerosis after the administration of darbepoetin alpha

We first describe the onset of acute myositis in a patient suffering from systemic sclerosis after the administration of darbepoetin alpha for renal failure-related anemia. Therapeutic implications and risks are discussed.