Thread by @DrStevenTChen

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HOW TO TREAT ACTINIC KERATOSES AT HOME, a #tweetorial/#medthread

AKA:how to keep practicing #socialdistancing in the era of #COVID19 by staying at home and taking care of those precancers without having to come to clinic!

#dermtwitter #medtwitter #MedEd #FOAMed pc:@dermnetnz

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1st, a caveat. Nothing subs for an in person exam, so this is not free license to tx things without a derm eval.

The reason for this #thread is that as the doctor seeing all urgent #dermatology pts today, I've gotten MANY calls from pts hoping to come get their AKs treated.

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Before we get to txs, let's start with the basics. What is an AK?

Clinically they are erythematous papules & plaques with gritty (sandpaper-like) scale. Some can be quite big. Then we call them "hypertrophic AKs."

These are precursor lesions to squamous cell carcinomas.

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What is the exact difference between an AK and an SCC-in situ? It comes to pathology. SCCIS will show full thickness keratinocytic atypia on biopsy (pic1), whereas the AK only shows atypia in part of the epidermis (the lower part - pic 2).

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So normally we will treat AKs with liquid nitrogen in clinic since there is a risk of progression of SCC. That said, the risk of each individual AK turning into an SCC is low. I think of AKs more as a marker of sun damage and overall risk of skin cancer for the patient.

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Given the above, I am more worried about patients who have HAKs or a LOT of AKs in a field. That's where field therapy comes in. These options include:
- Photodynamic Therapy (PDT)
- Imiquimod
- 5-FU topically
- 5-FU/calcipotriene
- Ingenol mebutate
- Diclofenac gel

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Since the whole goal right now is to keep pts at home, PDT doesn't seem like a great option since pts have to come in, get a photosensitizer painted on, & sit under a light for ~15 minutes! BTW, the pain from this is pretty intense.

Our review of PDT:
onlinelibrary.wiley.com/doi/full/10.11…

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Of the other options, 1st line for field tx is topical 5-FU. Pts apply this to the area of sun damage 1-2x daily for 2-4 weeks. This isn't pretty, & pts definitely complain of the irritation, drainage, & inflammation from tx, but that's how it works! (pic 1-typical, 2-severe)

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Luckily, @CaImmunoprevent from our department came around and came up with a new regimen. His paper shows that combining 5-FU with topical vitamin D analogue works well and with less irritation when applied for a shorter amount of time!

ncbi.nlm.nih.gov/pmc/articles/P…

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Another 1st line for field tx is imiquimod. It is a TLR-7 agonist that upregulates the immune system to fight the precancerous lesions. Interestingly, b/c of the mech, often applying this to an area will lead to inflammation of other AKs nearby that weren't directly treated.

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Ingenol mebutate came onto the AK scene ~10 years ago. I think it's main claim to fame is that the tx time is so short that patients finish treatment before they have a chance to stop from the irritation!

But the @nejm paper really argues for 5-FU!

nejm.org/doi/full/10.10…

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Other txs like retinoids, diclofenac, chemical peels can all be trialed, but in the name of EBM, I'd reach for one of the above first.

And remember - you don't even have to treat AKs! I think watchful waiting is totally reasonable... especially at a time like right now!

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So keep those AKs at home, continue #socialdistancing, #flattenthecurve, and lather up with a cream of your and your #dermatologist's choice. Also a plug for using #Telemedicine and #teledermatology options right now!

Good luck everyone! Stay safe (from 6 feet away)!