The correct answer is all of the above (choice “e”).
Most cases of dermatomyositis, which the patient’s presentation and lab results suggested, require nerve conduction studies, a check of serum aldolase levels, and skin and muscle biopsies to complete the work-up. However, the arrival at a diagnosis is only the first step.
Patients with dermatomyositis, particularly those older than 60, require evaluation for occult malignancy. There is evidence that the body’s immune response to the cancer is what drives the disease process. Hence the need for the studies listed, looking for breast, lung, and gastrointestinal cancers especially.
Dermatomyositis is thought to be an inflammatory myopathy, possibly driven by autoimmune factors. It is rare (about 1 to 22 per 100,000) and affects women more than men.
The “sunburn” rash is typical, especially on the face, chest, and dorsal hands, and usually clears completely when the cancer is found and cured. Other common findings include elevated creatine kinase, hand rashes (known as Gottron’s papules), and dystrophic calcification in skin and/or joints.
Aside from addressing a possible malignancy, treatment of dermatomyositis usually starts with glucocorticoids, eventually tapered and replaced by steroid-sparing agents such as azathioprine or cyclosporine. These drugs have dramatically increased the chances of survival and eventual cure.
It’s common for the photosensitivity to persist long after the myositis has resolved, which is why sunscreen and other sun-protective measures are advised.