BACKGROUND
On physical examination, the patient is awake and alert. Her heart rate is 100 bpm, her blood pressure is 174/82 mm Hg, her respiratory rate is 12 breaths per minute, and her oral temperature is 98.9°F (37.2°C). The patient’s heart rhythm is regular, no murmurs or gallops are heard, and the lungs are clear to auscultation. The abdomen is soft with normal bowel sounds. The skin examination reveals several hard nodules in the subcutaneous fat. One of the nodules appears to have resulted in a laceration associated with bleeding near the impact point of the fall.
Laboratory investigations reveal a normal complete blood count (CBC) and a normal basic chemistry panel. Twelve-lead ECG is ordered and shows a right bundle-branch block with no evidence of acute ischemia.
Plain radiographs of the chest, right shoulder, and right humerus are ordered. Images 1 and 2 show the lateral right humeral and anteroposterior (AP) shoulder radiographs, respectively. The lateral humerus radiograph (Image 1) demonstrates a minimally displaced fracture of the surgical neck of the humerus, with diffuse calcifications in the soft tissue. The patient also has severe osteopenia, which is most evident in the vertebral-body endplates and the humeral shaft. The AP radiograph of the shoulder (Image 2) demonstrates the acute fracture of the humerus superimposed on an old healed fracture with the same diffuse, soft-tissue calcifications.
What is the underlying medical condition?
{mosimage}HINT
The extraosseous findings are typical, although not pathognomonic of this disorder.{mosimage}
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Authors:
Craig Johnson, DO,
Diagnostic Radiology Residency Program,
Northeastern Ohio Universities College of Medicine-Canton Affiliated Hospitals
Joseph Mendiola, MD,
Clinical Assistant Professor of Radiology,
Musculoskeletal Radiology,
Northeastern Ohio Universities College of Medicine-Canton Affiliated Hospitals
Robert Reaven, MD, Assistant Professor of Radiology, Diagnostic Radiology,
Northeastern Ohio Universities College of
Medicine-Canton Affiliated Hospitals
eMedicine Editor:
Rick G. Kulkarni, MD
Assistant Professor,
Yale School of Medicine,
Section of Emergency Medicine,
Department of Surgery,
Attending Physician,
Medical Director,
Department of Emergency Services,
Yale-New Haven Hospital, Conn
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Dermatomyositis with a fracture through osteopenic bone secondary to steroid use: Further clinical investigation after the radiographs were viewed revealed that the patient was taking high doses of corticosteroids to treat her underlying medical condition of dermatomyositis. An idiopathic inflammatory myopathy, dermatomyositis is thought to have an autoimmune etiology. Dermatomyositis and polymyositis are commonly linked because of their overlapping symptoms, signs, and treatment. Their incidence is approximately 5.5 cases per 1,000,000, as Callen reported in 2006. The age distribution appears to be bimodal, with one peak at approximately 10 years of age and a second peak at approximately 50 years of age. Women are affected more often than men. In adults, dermatomyositis has been linked to an increased likelihood of cancer, particularly cancer of the lungs, breasts, ovaries, and GI tract.
{mosimage}Patients with dermatomyositis usually present with progressive proximal muscle weakness that affects the thighs, neck, upper back, and shoulders.{mosimage}
Many classic findings are observed on physical examination. The first relatively specific finding is a heliotrope rash, which is periorbital and purple in color. Edema may be associated with it. A violaceous rash occurs in photosensitive regions. Gottron papules are another classic finding, which manifests as dark-red plaques on the backs of the knuckles. These papules are separate from the hard subcutaneous nodules caused by associated calcinosis (for images, see the eMedicine article Dermatomyositis). Calcinosis is a rare but characteristic finding that usually occurs in the juvenile form; it is rare in the adult form. Dysphagia and interstitial lung disease are also common problems, and there have been reports of respiratory failure, but aspiration and pneumonia occur more often than frank respiratory failure.
The pathogenesis of dermatomyositis is characterized by changes in the microvasculature, including deposits of immune complexes in vessel walls and the presence of microtubuloreticular structures in endothelial cells. A muscle biopsy is required to distinguish dermatomyositis from polymyositis and inclusion-body myositis. The most common associated laboratory finding is an elevated creatine kinase or aldolase level caused by muscular inflammation. Antinuclear, anti–Mi-2, anti–Jo-1, and anti–signal recognition particle (SRP) antibodies can also be detected in cases of dermatomyositis. Electromyography can be helpful in characterizing myositis and for determining its distribution.
Dermatomyositis has many fascinating radiologic manifestations, of which the most striking are diffuse soft-tissue calcifications, as clearly seen in the radiographs from this case. Four patterns of calcification can be found: superficial masses, deep masses, deep linear deposits, and lacy reticular and/or subcutaneous deposits. The subcutaneous and linear (fascial) subtypes are the most common and can be seen most clearly on computed tomography (CT) scans. The differential diagnosis for soft-tissue calcifications includes venous insufficiency, infection, metastatic lesions, vitamin D overdose, scleroderma, tumoral calcinosis, heterotopic ossification, and myositis ossificans. Indirect manifestations of dermatomyositis include osteopenia secondary to chronic corticosteroid use, as in our patient.
Magnetic resonance imaging (MRI) is also helpful in detecting dermatomyositis because of its sensitivity in depicting even mild edema of the skeletal muscle. Increased signal intensity on spin-echo T2-weighted images is usually proportional to the patient’s clinical symptoms and can be helpful in finding the optimal site for muscle biopsy. In addition, changes in muscular signal intensity may be useful for monitoring treatment. MRI can also demonstrate fatty replacement and atrophy in chronic disease. Fatty stranding, which indicates inflammation, may be seen adjacent to the involved muscles on both CT scans and MRI.
Treatment for dermatomyositis usually involves an immunosuppressive agent, such as methotrexate, cyclophosphamide, or azathioprine; however, corticosteroids are the mainstays of therapy and are frequently used to treat the muscular component of dermatomyositis. High-dose intravenous immunoglobulin therapy is reserved for recalcitrant disease. In addition to other measures, such as avoidance of sunlight and the use of sunscreens, topical corticosteroids, and antimalarial agents, diltiazem may be helpful in treating calcinosis in some patients.
References
Callen JP: Dermatomyositis. eMedicine Journal [serial online]. 2006. Available at: http://www.emedicine.com/med/topic2608.htm. Accessed: March 18, 2007.
Crummy AB: The superficial soft tissues. In: Juhl JH, Crummy AB, Kuhlman JE, eds. Paul and Juhl’s Essentials of Radiologic Imaging. 7th ed. Philadelphia, Pa: Lippincott-Raven; 1998: 329-70.
Klippel JH, Crofford LJ, Stone JH, Weyland CM: Primer on Rheumatic Diseases. Atlanta, Ga: Arthritis Foundation; 2001: 369-73.
