Clinical clues separate cutaneous lupus, dermatomyositis

Benjamin F. Chong, MD, MSc

Benjamin F. Chong, MD, MSc

Treatment approaches to dermatologic conditions are not without controversy, but AAD Annual Meeting attendees gained insights about how to overcome a few from Benjamin F. Chong, MD, MSc, during “Controversies in Management and Treatment of Cutaneous Lupus and Dermatomyositis Patients” (U067) on March 6.

Cutaneous lupus and dermatomyositis often look like one another on biopsy, so dermatologists depend on clinical clues to differentiate the two.

“If a patient presents to me with signs of lupus, I have to make sure I think about dermatomyositis in my differential as well,” said Dr. Chong, University of Texas Southwestern Medical Center, Dallas.

Clinical clues include differences in the rash and systemic symptoms. A lupus rash presents on the dorsal fingers between the knuckles and in a V shape on the back, and is erythematous in color. Lupus gives patients joint aches predominantly, he said. The rash of dermatomyositis favors the knuckles, elbows, and knees, presents in a rectangular shawl shape on the patient’s back and is violaceous in color. It’s common for patients with dermatomyositis to have itchy scalps and muscle weakness.

“Interstitial lung disease is present in about 20 percent of patients who have dermatomyositis, and they generally get better with immunosuppressives. Nonspecific interstitial pneumonia is the most frequent type of interstitial lung disease seen in dermatomyositis, and it typically presents with a subacute to chronic cough or shortness of breath,” said Dr. Chong, adding that constitutional symptoms appear in up to one-third of patients.

Pulmonologists treat these patients with prednisone, and cyclophosphamide can be used in more severe cases. Studies show that most of these patients do well, Dr. Chong said, with one study showing that about one-third of the cases resolved on their own and half improved or became stable. However, in that study, disease worsened in 16 percent of patients.

The researchers noted that people who were older or had symptoms that came on acutely were more likely to have a worse prognosis, Dr. Chong said.

He recommends getting a high-resolution chest CT initially, which also is helpful for malignancy screening. He repeats the CT annually for two years, followed by annual PFTs, and the referral to pulmonary, especially if a patient has unexplained respiratory symptoms and abnormal findings.

There is a threefold increase in the risk of cancer, and cancer is present in 20-30 percent of dermatomyositis patients. Ovarian cancer is usually the most common malignancy found in females, and nasopharyngeal cancer is higher in Asians. Other malignancies associated with this disease are lung, pancreatic, stomach, and colon cancer, and non-Hodgkin’s lymphoma.

“Epidemiologic studies have generally found that most of these cancers are found within the first three years of diagnosis, but it can occur before the dermatomyositis rash,” Dr. Chong said.

Although the recommendations for screening vary, he uses guidelines from the European Federation of Neurological Societies. They include a CT of the chest, abdomen, and pelvis; a mammogram and pelvic ultrasound; and a colonoscopy for those over 50 if they haven’t had one within the last 10 years.

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