DESTIN, FLA. – A number of conditions are often misdiagnosed as malar rash, but certain clues can help in making the correct diagnosis, according to Dr. Ruth Ann Vleugels.
"One of the most helpful [clues] is this really prominent nasolabial sparing," Dr. Vleugels, assistant professor of dermatology at Harvard Medical School, and director of the autoimmune skin disease program at Brigham and Women’s Hospital, both in Boston, said at the annual Congress of Clinical Rheumatology.
Dr. Ruth Ann Vleugels
Prominent hemorrhagic crusting on the lips in conjunction with the rash is another telltale sign that the condition is a malar rash, she said.
Often, other skin conditions such as erythematotelangiectatic rosacea are diagnosed as malar rash. Erythematotelangiectatic rosacea is common, affecting about a third of all patients with light skin, and many patients with the condition report having a photosensitive rash on the cheeks.
"So, already you have two criteria for systemic lupus," she said, stressing that self-reported malar erythema is "honestly, not a great criteria" for a malar rash diagnosis.
These patients will have transient flushing on the face or may have papulopustular rosacea.
The nasolabial sparing is thus a "really critical clue to look for," she noted.
Also, a malar rash is not going to go away after a few hours like the flush of erythematotelangiectatic rosacea, but will last for several days, at least.
The presence of alopecia also can help distinguish malar rash from other conditions, as it is a common feature in SLE (systemic lupus erythematosus), Dr. Vleugels noted.
Perhaps the most important differential diagnosis in the dermatology-rheumatology clinic is chronic mid-facial erythema, she said.
When such erythema "hugs or involves the nasolabial fold," think dermatomyositis, Dr. Vleugels advised.
She presented a case in which a patient had a subtle heliotrope along with this type of chronic mid-facial erythema. The patient had been referred for lupus but had amyopathic dermatomyositis, and the subtle edema and erythema of the upper eyelids provided a clue that led to a diagnosis of gastric cancer in the patient.
"When it’s subtle, it’s often missed," she said of the heliotrope a violaceous to dusky erythematous rash, with or without edema, which occurs in a symmetric distribution involving periorbital skin.
Another clue that a rash may indeed be malar rash is the presence of nonblanching erythematous macules. Dr. Vleugels described a patient with this presentation on her chest, in addition to other signs of malar rash, including the nasolabial sparing and hemorrhagic crusting on the lips.
"This is essentially petechiae. This is a sign on her skin of active systemic involvement," she said of the rash on the patient’s chest.
Patients with true malar rash by definition have active SLE, she said.
"So we don’t let them leave even the dermatology clinic without checking their kidneys, blood pressure, renal function, etc.," she said.
Dr. Vleugels also noted that there is a generalized form of acute cutaneous lupus to keep in mind.
"Unfortunately, this is very difficult to distinguish clinically from the morbilliform drug eruption or a viral exanthema. It essentially blanches pink to red," she said, adding that macules and papules may be present.
A high level of suspicion for this condition is needed, even though it is quite rare. A biopsy can confirm the diagnosis, as classic changes associated with lupus will be present on biopsy, she said.
Dr. Vleugels reported having no disclosures.