Connective tissue disorders - an overview

Connective tissue disorders are characterised by pathology in one or more organ systems, the existence of autoimmunity in the form of autoantibody production or disordered cell-mediated immunity, vascular abnormalities such as Raynaud’s phenomenon, occlusive vascular disease and vasculitis (although the pathology is not entirely the result of vascular inflammation), arthritis or arthralgia, and skin disease.

This chapter provides a brief introduction in to connective tissue disorders and is set out as follows:

Classification 

Although numerous conditions are classified as connective tissue disorders, for the purpose of this website the following are considered the most relevant:

• Morphoea (syn. scleroderma)
• Limited / generalised / linear / craniofacial / mixed

• Systemic sclerosis

• Lupus erythematosus
• Cutaneous lupus erythematosus
• Systemic lupus erythematosus (refer to the chapter above)
  

• Dermatomyositis (and it's subgroups)

• Sjögren's syndrome

• Rheumatoid arthritis and Still's disease 

• Mixed connective tissue disorder (see below)

​Refer to the related chapters for more information.

Autoantibodies and connective tissue disorders 

• The presence of autoantibodies is an important feature of connective tissue disorders
• For more information refer to the section on Investigations
• It may be worth checking with your local pathology department as the tests performed may vary, and the spectrum of autoantibodies is continually evolving 

The importance of connective tissue disorders

Making the correct diagnosis at an early stage is important for many reasons:

• Discoid lupus erythematosus causes scarring of facial skin if left untreated

• Subacute lupus erythematosus, especially presenting in middle-aged or elderly individuals, may be drug-induced

• Complications associated with systemic lupus erythematosus can be reduced by early intervention

• Linear morphoea can affect limb growth and/or cause flexural contractions - it's natural history can be modified by treatment

• Early identification (and treatment) of specific organ involvement in systemic sclerosis improves outcomes

• Subgroups of adult dermatomyositis are associated with malignancy 

• Secondary Sjögren's syndrome can be found in many of the other connective tissue disorders

• Overlap between these different conditions can result in the mixed connective tissue disorder 

The mixed connective tissue disorder and overlap syndromes

There are many overlaps that occur within the spectrum of connective tissue disorders. One such condition is referred to as the mixed connective tissue disorder, which has the following features:

• This is a specific overlap condition associated with a very high titre of speckled antinuclear antibody (ANA), and RNP antibodies (U1-RNP) 

• Patients, predominantly female, show features of SLE, systemic sclerosis, dermatomyositis and polymyositis

• Raynaud's, arthritis/arthralgia, swollen-tight fingers, abnormal oesophageal motility, impaired pulmonary diffusing capacity and myositis are frequent. The incidence of clinical renal disease is 5%

• Response to treatments such as corticosteroids, methotrexate and hydroxychloroquine is generally good, although the condition can be more severe in children