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Diagnosing Bowen's disease can be difficult, so difficult in fact that one study showed 50% of the time doctors get it wrong. Are you one of those making this diagnostic mistake and risking your patients coming back time and time again because your treatments fail? Learning four simple steps will make all the difference to you and your patients.
Who is B in anyway? Why do we use doctor's names for medical conditions? We've got MC Bernie's point to help identify the appendix location, Jupiter and's contracture of the hand, which after 30 years of medical practice I still need to look at each time to spell it correctly. And spare a thought for Dr. Alzheimer. Imagine the scene: "Hello, I'm Dr. Alimer. Sorry, what was your name again?" I guess we should be thankful his name wasn't something else. Fortunately, the name Bowen is short and easy to remember compared to its proper medical name, insitu squamous cell carcinoma or intraepidermal carcinoma.
What does it look like on your patient's skin? Let's have a bit of fun with a quick quiz on four of my patients. Pick from this list the diagnosis you think is the most likely for each of these patients. Pen and paper ready. You can press the pause button if you want more time. And here's the answers: They all have confirmed Bowen's disease. Sorry about that.
So, step one to mastering Bowen's disease is quite simple: just consider it when you're trying to make a diagnosis of any chronic, non-healing, non-itchy pink red patch, in particular if it's got scale and has a clear, well-demarcated border. To think, "Could this be Bowen?" In Bowen's disease, the abnormal skin cells involve the full thickness of the epidermis. Most importantly, these abnormal cells don't breach the basement membrane, otherwise it will have transformed from an insitu squamous cell carcinoma or B to an invasive squamous cell carcinoma. It's on the spectrum of skin damage caused by a lifetime accumulation of sun ultraviolet radiation damage. Because of their inbuilt sun protection, people with a skin of color rarely develop Bowen's, and in patients below the age of 30, it's as rare as hen's teeth at a vegan buffet. Found most often in the over 60s. Bowen can appear almost anywhere on the skin, but most commonly on ultraviolet light-exposed areas like the head, neck, fingers, and hands. But one UK survey reported the majority were on the lower legs, and that's my experience with Bowen's in my patients. The vast majority are single, solitary lesions, but several patches can occur at once, especially in patients with immunosuppression, for instance, after a kidney transplant.
This is your second step to master your Bowen's: know who is at high risk and where on the body most likely to find it. What about the dermoscopy of Bowen's? Well, you tell me. Here's the dermoscopic photos of my patients from that earlier mini-quiz. What do you notice? How many of them have scales? What about the background color? What about those odd vessel shapes? These are called different names, but you'll often hear them called glomular, and don't try saying that fast after eating a whole pizza unless you want to see it again. This name is used because they look a little bit like the glomerular apparatus in the kidney, but these vessels in Bowen's have nothing to do with the kidney. When starting out in dermoscopy, I often confuse the term glomular with globular. Am I the only one? A globule is a discrete area larger than a dot, and pigmented globules are very commonly seen in nevi. If glomular is too much of a tongue-twister for you, then do what I do: use the terms coiled vessels or knotted vessels. Why do they look like this? Here's a cross-section of skin with a dermal papilla pushing up into the epidermis. When we look down at the skin using a dermoscope, this is what we see. Here's a few other vessel shapes that you will commonly see in dermoscopy in other conditions. What do you think of this particular dermoscopic picture? On dermoscopy, it would do quite nicely for Bowen's disease, right? Pink background, coiled vessels, even you space throughout. However, if you look at the wider picture, we find it's actually a rash.
There are two common pitfalls to avoid: one, psoriasis. Always ask about a history of psoriasis and check the typical sites for other lesions. Secondly, varix eczema can look similar, and that's also found on the legs, a common place for Bowen's. It usually itches and should respond to topical steroids and emollients. What if you still aren't sure? Then sometimes histology is needed with something like a punch biopsy. Therefore, step three to mastering Bowen's is learning to confirm the diagnosis using dermoscopy, maybe therapeutic trials, and failing that, sometimes a punch biopsy. Note that most consultant dermatologists in secondary care would treat a clinical dermoscopic classic Bowen without requiring histology.
Remember this fact: a patch of Bowen's has a roughly 5% or one in 20 chance of turning into an invasive squamous cell cancer in the patient's lifetime. That means it has a 95% chance that it won't do that in their lifetime. So, do you have to treat Bowen's disease when you suspect it? Well, on statistics like that, no. Bear in mind, Bowen's is usually asymptomatic, and the principle of "first, do no harm" is a good starting point. In my very frail and elderly patients, a small patch of Bowen's is usually the least of their worries. Reassurance and monitoring for new changes is a very reasonable option.
What if the patient would like treatment? I'm going to share with you my own simple treatment decision-making process. It's based on the 2022 British Association of Dermatologists guidelines, which you can download using a link in the video description below. When a patient presents with a skin lesion, the first step is thinking, "Could this be Bowen?" A clinical assessment will help you decide if this patient is at risk of Bowen's, and dermoscopy can help you try and confirm the diagnosis. What if you're uncertain? I consider then if it could be psoriasis or eczema and discuss a therapeutic trial using a potent steroid cream with my patient. If you do this, ensure you take personal responsibility for the follow-up of that patient, perhaps three to four weeks later. If the response to the steroid cream is very poor, it's probably not eczema or psoriasis. Worrying features to concern you are a rapid growth, ulceration, bleeding, a thickened base, and pain. These are much more common in something like a squamous cell carcinoma. Look at this 12 mm scale patch on this 77-year-old lady's neck. It's been growing slowly for three to four months, and it was sore. The scale kept dropping off and reforming. It sits on a red, inflamed-looking base. It could be a wart, it could be a seborrheic keratosis, but you cannot rule out a squamous cell carcinoma. So I referred on the Cancer Care Pathway. On excision, it showed that this was actually Bowen's. Or take this 89-year-old lady who had a previous invasive squamous cell carcinoma removed from her forehead. This red, raised, bleeding 8 mm patch had been growing for only three weeks. Dermoscopy showed some very large coiled vessels with some hemorrhage. You can occasionally get coiled vessels in an invasive squamous cell carcinoma, and I referred her on the Cancer Care Pathway, and the histology was hyperkeratotic Bowen's. Boing, boing are disordered keratinocytes, and the amount of scale can vary. If you're uncertain, sometimes a punch biopsy can make all the difference to the diagnosis. Otherwise, the first rule of primary dermoscopy is: if in doubt, refer it out. Just make sure you learn from that process.
What if you're pretty certain that this is a typical patch of Bowen's? Well, discuss the treatment options with your patients. Firstly, conservative management. This would involve moisturizers, giving the patient the leaflet, and educating them about the condition, and teaching them to monitor the patch, reporting any new changes to you. If you opt for active treatment, then the guidelines say: "insitu squamous cell carcinoma that is small and at low risk may be managed in primary care by a general practitioner who is capable of establishing a clinical diagnosis and initiating treatment options as per the guidelines." For me, there are two options I think all GPs can learn to use safely. If you're new to treating Bowen's disease, start with these. Firstly, cryotherapy. These are ideal for small patches of Bowen's, and a 30-second freeze with a 3 mm margin around included as well gives you a good 95% cure rate. Secondly, 5-fluorouracil cream. I tend to prescribe it twice a day for four weeks. Make sure you counsel your patients well about how to use it. The inflammation is very marked. Ensure you follow up your patients closely. Bear in mind there are high-risk areas that I would probably avoid treating myself: that's on the face, and especially around the eyes, and where there are large patches on the lower leg due to poor healing concerns. These I might refer on to secondary care. My fourth step to mastery of Bowen's is managing patients well in primary care with the tools that we have available.
Who is Bowen? He was a professor of Dermatology at Harvard Medical School. In 1912, he wrote up two case reports giving them the descriptive title "Chronic typical epithelial proliferation." Bit of a mouthful, that is, isn't it? A friend probably suggested to him down the pub after a few drinks, "Why don't we attach your name to it?" So we did, and we've been suffering the consequences of that one round of drinks ever since. If you haven't already, you need to watch these two videos to complete your understanding of the range of skin damage the ultraviolet light causes to your patient's skin.