This month's news from across the specialty
What's hot
July 1, 2020
In this monthly column, members of Dermatology World's Editorial Advisory Workgroup identify exciting news from across the specialty.
What are COVID toes? Lindy Fox, MD, professor of dermatology at UCSF, weighed in with her expert opinion on everydayhealth.com (“What are ‘COVID toes’? Must know facts about the strange coronavirus symptom”). COVID toes are pernio-like lesions — itchy, painful, red-to-purple bumps on the toes and sometimes the fingers. Although much of the evidence is anecdotal, “we feel strongly that these symptoms are connected to the virus,” said Dr. Fox. European dermatologists and podiatrists initially picked up on the trend, and now we are seeing more of it in the U.S. The pathogenesis is unclear but thought to be secondary to immune activation to the virus, which triggers inflammation in the form of vasculitis or vasculopathy. Interestingly, COVID toes seem to occur among young, healthy people recovering from the virus, or those who are asymptomatic. Dr. Fox noted that “with older people, the immune response is not as robust, so the response isn’t likely triggered.” As far as what to expect, patients may experience symptoms for a week to a month, and dermatologists are prescribing high-potency topical steroids and aspirin for treatment. For more in-depth discussion on the potential dermatologic manifestations of COVID-19 and what dermatologists need to know, check out the series of articles published in DW Insights and Inquiries by Warren Heymann, MD, and others.
Is pernio the new influenza?
I don’t mean to conflate COVID-19, with which pernio-like “COVID toes” has been associated, with influenza. (Others have been less circumspect.)
But influenza’s etymology might hold lessons for our understanding of pernio, COVID-19-associated or otherwise. Influenza is caused by a virus. But the term itself — influenza — is an Italian word that means, literally, “influence.” It reflects the idea, held during early influenza pandemics, that the disease was caused by influence of the stars.
The word pernio comes from “heel.” Chilblains, a synonym for pernio, is thought to derive from the Old English words “chill” and “blegen” (sore). The traditional pathophysiologic explanation for pernio is that the lesions result from abnormal inflammatory response to cold exposure. The timing does make sense: Pernio typically occurs in cold, damp climes. But no cold snap presaged the epidemic of pernio-like lesions in spring 2020. Rather, the COVID-19 pandemic did. It’s chilblains sine chill.
The exact relationship between pernio-like lesions and COVID-19 awaits clarification. However, a connection is suspected, possibly mediated by viral-induced interferon release (JAAD Case Rep. 2020. Apr 18).
That proposed pathophysiology has implications for garden-variety pernio. Could we have been misattributing pernio to cold and damp, rather than to viral infections (other than COVID-19) that just happen to occur during those conditions?
Cold for pernio might prove just as innocent as the stars for flu.
Non-surgical options for loss of scalp hair have remained relatively static and historically have been restricted to creative hairstyles and prosthetic wigs, topical preparations, or systemic medications that manipulate hormonal regulation with estrogen supplements or an alteration in endogenous testosterone synthesis. To fill this dearth in choices, there has been a growing interest in the use of autologous platelet rich plasma (PRP) injections to promote hair restoration. Whole blood is obtained, an anticoagulant is added, and the solution is centrifuged. The supernatant layer of plasma primarily contains platelets with a small fraction of white blood cells. The final platelet concentration should be 3-8 times of what is found in whole blood (a minimum of 1,000,000 platelets/micro liter). Platelets contain dense alpha granules, and upon their activation can lead to the production of several growth factors that induce perifollicular angiogenesis and the proliferation of dermal papillary cells. Hairs stay in growth phase longer, at a higher number, with less perifollicular inflammation and improved blood supply. The growth factors appear to overcome the hormonal and genetic signals known to induce alopecia and support healthy hair development and shaft caliber making PRP an attractive option in treating hair loss.
The consensus on treatment protocol is still evolving and many studies utilize serial microdroplet injections of approximately 0.2 cc in the subdermal space every four weeks for three consecutive months with booster treatments on a quarterly basis. At 12-month follow up, there is reportedly high patient satisfaction with few adverse events.
There remains much inconsistency and therefore PRP has not universally been accepted as a reliable treatment for hair loss. The devices to obtain platelets vary in many ways that impact treatment response, including if they are open or closed (not exposed to environmental factors), the separation methodology (the use of citrate dextrose or sodium nitrate), the centrifugation time, spin speed (excessive speed can cause platelet lysis) and the purity of the resultant PRP, and the presence or absence of leukocytes (Dermatologic Surgery. 2020; 46:93-102).
The biologic activity of PRP is not fully understood; most downstream effects rely on platelet activation with release of signaling molecules: growth factor, cytokines, and chemokines. Although study sample sizes are small and are not standardized with randomized controlled trials, basic science data is encouraging and the efficacy of PRP shows promise as an off-label treatment for alopecia.
The diagnosis of skin infections can be a challenging aspect of practicing dermatology. Specifically, deep tissue infection may be the most difficult in this category. In a retrospective, single institution study in JAAD, Shaigany and colleagues examined 179 patients who had a skin biopsy for routine histopathology and tissue culture.
About 21% of the patients had a positive culture. An organism was identified by histopathology in 7% of the cases. There was 10% concordance, with a low Kappa coefficient (0.25, minimal agreement). Histopathology was more sensitive in detecting fungal organisms. Tissue culture was more sensitive in detecting Gram-negative bacteria. Dermatologists must be cognizant of these issues and remember that sending both tissue culture and routine histopathology increases the sensitivity in detecting a deep tissue infection. Additionally, if possible, biopsy and culture should be performed prior to treating with antimicrobial agents.
