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Dr. Misha Rosenbach
Diagnosing cases “can be hard and folks should keep a very open mind and consider monkeypox virus,” said Misha Rosenbach, MD, a University of Pennsylvania dermatologist and member of the American Academy of Dermatology’s ad hoc task force to develop monkeypox content.
Although it’s named after a primate, it turns out that monkeypox is quite the copycat. As dermatologists have learned, its lesions can look like those caused by a long list of other diseases including herpes, varicella, and syphilis. In small numbers, they can even appear to be insect bites.
To make things more complicated, a patient can have one or two lesions – or dozens. They often cluster in the anogenital area, likely reflecting transmission via sexual intercourse, unlike previous outbreaks in which lesions appeared all over the body. “We have to let go of some of our conceptions about what monkeypox might look like,” said dermatologist Esther Freeman, MD, PhD, associate professor of dermatology, Harvard University, Boston, and a member of the AAD task force.
Dr. Esther Freeman
To make things even more complicated, “the spectrum of illness that we are seeing has ranged from limited, subtle lesions to dramatic, widespread, ulcerative/necrotic lesions,” said Dr. Rosenbach, associate professor of dermatology at the University of Pennsylvania, Philadelphia.
But monkeypox has unique traits that can set it apart and pave the way toward a diagnosis, dermatologists say. And important patient data can help dermatologists gauge the likelihood of a case: Almost 99% of cases with data available have been in men, and among men with available information, 94% reported male-to-male sexual or close intimate contact during the 3 weeks before developing symptoms, according to a CDC report tracking cases from May through late July. So far, cases in women and children are extremely rare, although there have been some reported in the United States.
Are dermatologists likely to see monkeypox in the clinic? It’s unclear so far. Of four dermatologists interviewed for this article, only one has seen patients with monkeypox in person. But others say they’ve been sought for consultations. “I have been asked by infectious disease colleagues for advice remotely but have not seen it,” said dermatologist Howa Yeung, MD, MSc, assistant professor of dermatology, Emory University, Atlanta. “Most of the time, they’re catching all the symptomatic cases before any need for dermatology in-person referrals.”
Dr. Howa Yeung
Still, the rapid rate of growth of the outbreak – up from 3,487 in the United States on July 25 to 12,689 as of Aug.16 – suggests that more dermatologists will see cases, and consultations may become more common too.
Know your lesions
Lesions are the telltale signs of symptomatic monkeypox. According to a recent New England Journal of Medicine study of 528 monkeypox cases from 16 nations, diagnosed between April 27 and June 24, 2022, 95% had skin lesions (58% were vesiculopustular), most commonly in the anogenital area (73%), and on the trunk/arms/or legs (55%) and face (25%), and the palms/soles (10%).
However, “the current monkeypox outbreak often presents differently from the multiple classic vesiculopustules on the skin we see in textbooks,” Dr. Yeung said. “Sometimes people can present with throat pain or rectal pain, with isolated pharyngitis or proctitis. Sometimes there are so few lesions on the skin that it can be easily confused with a bug bite, folliculitis, herpes, dyshidrotic eczema, or other skin problems. This is where dermatologists will get consulted to clarify the diagnosis while the monkeypox PCR test is pending.”
Dr. Rosenbach, who has provided consultation services to other physicians about cases, said the lesions often appear to be vesicles or pustules, “but if you go to ‘pop’ it – e.g., for testing – it’s firm and without fluid. This is likely due to pox virus inclusion, similar to other diseases such as molluscum,” caused by another pox virus, he said. Molluscum lesions are “characteristically umbilicated, with a dimple in the center, and monkeypox lesions seem to be showing a roughly similar morphology with many bowl- or caldera-shaped lesions that are donut-like in appearance,” he added.
Over time, Dr. Rosenbach said, “lesions tend to evolve slowly from smaller flesh-colored or vaguely white firm papules to broader more umbilicated/donut-shaped lesions which may erode, ulcerate, develop a crust or scab, and then heal. The amount of scarring is not yet clear, but we anticipate it to be significant, especially in patients with more widespread or severe disease.”
Jon Peebles, MD, a dermatologist at Kaiser Permanente in Largo, Md., who has treated a few in-person monkeypox cases, said the lesions can be “exquisitely painful,” although he’s also seen patients with asymptomatic lesions. “Lesions are showing a predilection for the anogenital skin, though they can occur anywhere and not uncommonly involve the oral mucosa,” said Dr. Peebles, also a member of the AAD monkeypox task force.
Dr. Jon Klint Peebles
Dr. Yeung said it’s important to ask patients about their sexual orientation, gender identity, and sexual behaviors. “That is the only way to know who your patients are and the only way to understand who else may be at risks and can benefit from contact tracing and additional prevention measures, such as vaccination for asymptomatic sex partners.” (The Jynneos smallpox vaccine is Food and Drug Administration–approved to prevent monkeypox, although its efficacy is not entirely clear, and there’s controversy over expanding its limited availability by administering the vaccine intradermally.)
It’s also important to keep in mind that sexually transmitted infections (STIs) are common in gay and bisexual men. “Just because the patient is diagnosed with gonorrhea or syphilis does not mean the patient cannot also have monkeypox,” Dr. Rosenbach said. Indeed, the NEJM study reported that of 377 patients screened, 29% had an STI other than HIV, mostly syphilis (9%) and gonorrhea (8%). Of all 528 patients in the study (all male or transgender/nonbinary), 41% were HIV-positive, and the median number of sex partners in the last 3 months was 5 (range, 3-15).