**2.1 Nomenclature and classification**

These different classifications are included:

### **2.1.1 Polymyositis and dermatomyositis (Hansell, et al., 2005)**

	- i. malignant disease
	- ii. other collagen vascular disease (overlap syndrome)

### **2.1.2 Inflammatory disease of muscle (Resnick & Kransdorf, 2005)**

Idiopathic inflammatory myopathies:


Dermatomyositis 131

involvement occurs in 50% of patients and contributes directly to death in about 10% of

**2.2.6.2** Other systemic involvement includes myocardial disease, pericarditis, renal,

**2.2.7** In addition to typical muscular involvement with bilateral symmetric superficial oedema and palpable sheetlike confluent calcifications, especially in the thigh muscles, there may also be pointing and resorption of the terminal tufts of the fingers with distal soft tissue loss. The 'floppy-thumb' sign has been described as a common feature (Resnick &

**2.2.8** The aforementioned clinical features may be readily diagnosed on physical

**2.3** After effective treatment for dermatomyositis, the soft tissue oedema may decrease or disappear altogether, though fibrosis, muscle atrophy and contractures may become apparent in the later stages of the disease. With constant aggressive prednisone treatment, the development of progressive muscular weakness, contractures and disabling calcifications occur in less than 20% of patients with childhood dermatomyositis (Hesla, et

**2.4** Polymyositis/dermatomyositis may precede, accompany or follow malignant disease, though usually found within one year of diagnosis. The course of the myopathy often follows the course of the malignancy, improving when the malignancy is treated, and increasing with relapse, suggesting that it is a true paraneoplastic symptom (Hansell, et al., 2005). There is an increased prevalence of malignant neoplasms of the breast, prostate, lung,

**2.5.1** Furthermore for many patients, the manifestations of the disease process are incompatible with a single diagnosis. These patients appear to have more than one collagen vascular disease, and the diagnosis of an overlap syndrome (mixed connective tissue disease) is suggested to correlate the diverse clinical, imaging and laboratory findings. As many as 85% of patients with connective tissue disease may be included in this category.

**2.5.2** The overlap syndrome includes features similar to dermatomyositis, scleroderma, lupus erythematosus and rheumatoid arthritis, although Sjögren's syndrome and

**2.6** There is no cure for dermatomyositis, but the symptoms can be treated. Options include medication (e.g. corticosteroids or immunoglobulins), physical treatment (e.g. removal of calcium deposits that may cause nerve pain and recurrent infections), exercise, heat

**2.7 Other inflammatory diseases of muscles (Resnick & Kransdorf, 2005) include** 

**2.7.1** Inclusion body myositis, occurs more often in men older than 55 years, the clinical findings resemble those of polymyositis, but there are distinctive microscopic findings with

The existence of this entity is not universally accepted (Resnick & Kransdorf, 2005).

patients.)

Kransdorf, 2005).

al, 1990).

examination of the patient.

neurological and ocular abnormalities.

ovary, gastrointestinal tract and kidney (Dähnert, 2007).

polyarteritis nodosa could also be included.

inclusion bodies noted.

treatment, orthotics and assisting devices, and rest.


Other inflammatory myopathies:


#### **2.1.3 Further classification (Resnick & Kransdorf, 2005)**

Type I. Typical polymyositis (most common, 35% of patients)

Type II. Typical dermatomyositis (25% of patients)

Type III. Typical dermatomyositis with malignancy. (Malignancy occurs in 15-25%)

Type IV. Childhood dermatomyositis (20% of patients)

Type V. Acute myolysis (3% of patients)

Type VI. Polymyositis in Sjögren's syndrome and other connective tissue diseases (5%).

**2.2.1** The most constant clinical finding is muscle weakness, the initial symptom in about 50% of patients. (Resnick & Kransdorf, 2005). Symmetric involvement of the proximal muscles is most characteristic. Clinical presentation may be with an acute, subacute or chronic illness, with progressive symmetric weakness of the girdle and neck muscles. In the acute form, muscle pain and tenderness are common features. Low grade fever and fatigue are further manifestations.

**2.2.2** In children the acute form is more common with clinical features of fever, joint pain, lymphadenopathy, splenomegaly and subcutaneous oedema. The skin changes tend to be very severe, and prognosis is poor.

**2.2.3** In adults the onset is often more insidious with periods of spontaneous remission. On relapse, skin changes are the first symptom in 25% of patients. These are more severe and more frequent in children. There are no skin changes in polymyositis, however, in dermatomyositis the changes are characteristic, with a heliotrope periorbital rash and violaceous/red papular rash over bony prominences.

**2.2.4** In addition to the typical proximal muscle weakness and the skin rash, the raised muscle enzymes and characteristic electromyography and muscle biopsy, also contribute to characteristic clinical criteria.

**2.2.5** Further clinical features include: Arthralgia and arthritis, with typical symmetrical involvement of the small joints of the fingers, the wrists and the knees. Permanent involvement is uncommon.

**2.2.6.1** Visceral involvement due to dermatomyositis may include pharyngeal and oesophageal symptoms with dysphagia, pulmonary disease due to respiratory muscle weakness with aspiration pneumonia and/or interstitial lung disease. (Pulmonary

Myositis associated with malignancy

Myositis associated with eosinophilia

Myopathies caused by infection

Type V. Acute myolysis (3% of patients)

are further manifestations.

very severe, and prognosis is poor.

characteristic clinical criteria.

involvement is uncommon.

Myopathies caused by drugs and toxins

Type II. Typical dermatomyositis (25% of patients)

Type IV. Childhood dermatomyositis (20% of patients)

violaceous/red papular rash over bony prominences.

**2.1.3 Further classification (Resnick & Kransdorf, 2005)**  Type I. Typical polymyositis (most common, 35% of patients)

Type III. Typical dermatomyositis with malignancy. (Malignancy occurs in 15-25%)

Type VI. Polymyositis in Sjögren's syndrome and other connective tissue diseases (5%).

**2.2.1** The most constant clinical finding is muscle weakness, the initial symptom in about 50% of patients. (Resnick & Kransdorf, 2005). Symmetric involvement of the proximal muscles is most characteristic. Clinical presentation may be with an acute, subacute or chronic illness, with progressive symmetric weakness of the girdle and neck muscles. In the acute form, muscle pain and tenderness are common features. Low grade fever and fatigue

**2.2.2** In children the acute form is more common with clinical features of fever, joint pain, lymphadenopathy, splenomegaly and subcutaneous oedema. The skin changes tend to be

**2.2.3** In adults the onset is often more insidious with periods of spontaneous remission. On relapse, skin changes are the first symptom in 25% of patients. These are more severe and more frequent in children. There are no skin changes in polymyositis, however, in dermatomyositis the changes are characteristic, with a heliotrope periorbital rash and

**2.2.4** In addition to the typical proximal muscle weakness and the skin rash, the raised muscle enzymes and characteristic electromyography and muscle biopsy, also contribute to

**2.2.5** Further clinical features include: Arthralgia and arthritis, with typical symmetrical involvement of the small joints of the fingers, the wrists and the knees. Permanent

**2.2.6.1** Visceral involvement due to dermatomyositis may include pharyngeal and oesophageal symptoms with dysphagia, pulmonary disease due to respiratory muscle weakness with aspiration pneumonia and/or interstitial lung disease. (Pulmonary

Inclusion body myositis

 Myositis ossificans Localized (focal) myositis

Other inflammatory myopathies:

involvement occurs in 50% of patients and contributes directly to death in about 10% of patients.)

**2.2.6.2** Other systemic involvement includes myocardial disease, pericarditis, renal, neurological and ocular abnormalities.

**2.2.7** In addition to typical muscular involvement with bilateral symmetric superficial oedema and palpable sheetlike confluent calcifications, especially in the thigh muscles, there may also be pointing and resorption of the terminal tufts of the fingers with distal soft tissue loss. The 'floppy-thumb' sign has been described as a common feature (Resnick & Kransdorf, 2005).

**2.2.8** The aforementioned clinical features may be readily diagnosed on physical examination of the patient.

**2.3** After effective treatment for dermatomyositis, the soft tissue oedema may decrease or disappear altogether, though fibrosis, muscle atrophy and contractures may become apparent in the later stages of the disease. With constant aggressive prednisone treatment, the development of progressive muscular weakness, contractures and disabling calcifications occur in less than 20% of patients with childhood dermatomyositis (Hesla, et al, 1990).

**2.4** Polymyositis/dermatomyositis may precede, accompany or follow malignant disease, though usually found within one year of diagnosis. The course of the myopathy often follows the course of the malignancy, improving when the malignancy is treated, and increasing with relapse, suggesting that it is a true paraneoplastic symptom (Hansell, et al., 2005). There is an increased prevalence of malignant neoplasms of the breast, prostate, lung, ovary, gastrointestinal tract and kidney (Dähnert, 2007).

**2.5.1** Furthermore for many patients, the manifestations of the disease process are incompatible with a single diagnosis. These patients appear to have more than one collagen vascular disease, and the diagnosis of an overlap syndrome (mixed connective tissue disease) is suggested to correlate the diverse clinical, imaging and laboratory findings. As many as 85% of patients with connective tissue disease may be included in this category. The existence of this entity is not universally accepted (Resnick & Kransdorf, 2005).

**2.5.2** The overlap syndrome includes features similar to dermatomyositis, scleroderma, lupus erythematosus and rheumatoid arthritis, although Sjögren's syndrome and polyarteritis nodosa could also be included.

**2.6** There is no cure for dermatomyositis, but the symptoms can be treated. Options include medication (e.g. corticosteroids or immunoglobulins), physical treatment (e.g. removal of calcium deposits that may cause nerve pain and recurrent infections), exercise, heat treatment, orthotics and assisting devices, and rest.

#### **2.7 Other inflammatory diseases of muscles (Resnick & Kransdorf, 2005) include**

**2.7.1** Inclusion body myositis, occurs more often in men older than 55 years, the clinical findings resemble those of polymyositis, but there are distinctive microscopic findings with inclusion bodies noted.

Dermatomyositis 133

thigh, with a possible abscess, despite 1 week of treatment with antibiotics. A shell of curvilinear calcification was noted around the chest on the PA chest radiograph (Fig. 2a). Predominant calcification was seen of the lateral chest wall, the axillary region and within the neck, superior and parallel to the first rib, with bilateral changes. Some tramline-like calcifications were detected overlying the peripheral midzones on both sides, thereby mimicking pleural or pulmonary parenchymal disease. However, these rather coarse calcifications were situated in the superficial soft tissue and superimposed on the lung fields. No bony abnormality was observed. No cardiac or pulmonary abnormalities were detected.

a. b.

c. Fig. 1. a.,b.,c. Case 1. A 17–year-old teenager with known dermatomyositis was referred for chest and pelvis radiographs. There is slight left based patchy opacification. Furthermore there is a minimal linear calcification of the left side of the neck (Fig. 1a,b). (Fig. 1b is a magnified image to demonstrate the calcification). The AP pelvis X-ray demonstrates extensive linear plaque-like calcification overlying the outer aspect of the left iliac bone (Fig.

1c). The radiological features correlate exactly with the clinical diagnosis of

dermatomyositis.

**2.7.2** Focal nodular myositis is a benign inflammatory muscle disorder, mostly affecting the thigh or lower extremity, and patients present with a painful, localised intramuscular mass. The histology of the small nodules or pseudotumours is similar to polymyositis, and the disease may progress to a more generalised distribution typical of polymyositis.

**2.7.3** Eosinophilic myositis may present with an eosinophilic inflammatory infiltrate in skeletal muscle as a localised disorder, or as a generalised disease.

**2.7.4** Drug-related myositis may vary from acute inflammatory changes to chronic fibrosis, the latter may appear as a consequence of direct intramuscular injection of drugs in the deltoid or quadriceps muscles. Alcohol, aspirin, penicillin and sulphonamides may also lead to myopathic changes.
