Polymyositis, invasion of non-necrotic muscle fibres, and the art of repetition

doi:10.1136/bmj.329.7480.1464

From trainee to consultant, BMJ Group offers doctors around the world tailored information, special events, learning resources and recruitment services at every step along their career path.

... by doctors, for doctors, for patients
We are open for entries!

Online learning

BMJ Learning

High-quality CME / CPD for doctors and other healthcare professionals. BMJ Learning features hundreds of accredited, peer-reviewed learning modules in text, video, and audio formats. Find out more

Courses and Qualifications

BMJ Masterclasses

BMJ Masterclasses, led by experts, help clinicians to use the latest evidence and recent guidelines in practice and meet their CPD/CME requirements. Find out more

Exam Preparation

The leading provider of online exam preparation, helping over 167,000 healthcare professionals to pass their exams. Find out more

onExamination

Search all BMJ research articles:

From

Limit by

Access to the full text of this article requires a subscription or payment. Please log in or subscribe below.

Gerald J D Hengstman, resident in neurology,
Baziel G M van Engelen, neurologist

¹ Neuromuscular Centre Nijmegen, Department of Neurology, University Medical Centre Nijmegen, PO Box 9101, 6500 HB Nijmegen, Netherlands

Correspondence to: G J D Hengstman

The presence of cellular inflammatory infiltrates with invasion of non-necrotic muscle fibres has become a prerequisite for the diagnosis of polymyositis, but a structured literature search shows that the research evidence is insufficiently strong for this histological feature to be used as a diagnostic criterion

A dispute has erupted over the diagnostic criteria for polymyositis, a disorder characterised by progressive muscle weakness and the presence of inflammatory infiltrates in skeletal muscle tissue that could leave many myositis patients diagnostically adrift and excluded from receiving potentially effective treatment. It might also lead to the results of clinical studies performed by one specialist not being accepted by another because of disagreement over the diagnostic criteria used. The dispute focuses on the histopathological characteristics of polymyositis and whether the presence of inflammatory infiltrates invading non-necrotic muscle fibres is a prerequisite for the diagnosis.

To examine the validity of this presumed histological characteristic of polymyositis, we traced the original source of this statement by performing a structured literature search. We subsequently studied the original source in the light of present day knowledge on myositis.

The dispute

The idiopathic inflammatory myopathies are a group of heterogeneous disorders characterised by acquired progressive muscle weakness and inflammatory infiltrates in skeletal muscle tissue. The three main disorders in this group are dermatomyositis, polymyositis, and inclusion body myositis. These diseases differ strongly from each other, both clinically and pathophysiologically. Dermatomyositis seems to be a humorally mediated angiopathy resulting in myositis and a typical dermatitis.1 Polymyositis is traditionally seen as an inflammatory myopathy mediated by cytotoxic T cells, which can occur in the context of another inflammatory connective tissue disease such as systemic sclerosis.1 Inclusion body myositis, which is seen mainly in elderly people and is clinically characterised by slowly progressive asymmetric muscle weakness, is thought to be a degenerative …