Unraveling Nail Psoriasis: Distinguishing Features and Diagnostic Approaches

Announcer:
You’re listening to Clinician’s Roundtable on ReachMD. On this episode, Dr. Shari Lipner will discuss best practices for diagnosing nail unit psoriasis. Dr. Lipner is an Associate Professor of Clinical Dermatology and Director of the Nail Center at Weill Cornell Medicine, and she spoke on this topic at the 2025 AAD Annual Meeting. Let’s hear from her now.

Dr. Lipner:
There’s no single characteristic of nail unit psoriasis that can distinguish it from other nail diseases that we know of, and there’s no group of characteristics. However, there are some common characteristics of nail unit psoriasis that can help us make the diagnosis, and this depends on whether the nail matrix or the nail bed is involved, but often it’s both the nail matrix and the nail bed. So for nail matrix changes, we see nail plate pittin cg and red spots in the lunula, and when the pits coalesce together, we see crumbling. For nail bed psoriasis, we see onycholysis, subungual hyperkeratosis, oil drop or salmon spots, and splinter hemorrhages—but often, we’ll see a combination of these changes. And typically, I like to look at the fingernails as opposed to the toenails because toenail findings tend to be a lot less specific and can often resemble onychomycosis, so if I have the choice of really analyzing closely the fingernail or the toenail, I look more closely at the fingernails for those characteristics.

To diagnose nail psoriasis, it’s mainly a clinical diagnosis, so we would look at the nails and look for these characteristic features of nail matrix, nail bed, pitting, onycholysis, and subungual hyperkeratosis, and then look for some negatives, such as scale between the feet. That would more sugge st the diagnosis of onychomycosis with tinea pedis. And so it’s mainly a clinical diagnosis, but I don’t like to go on clinical diagnosis alone, so I’d like to have some supporting tests to help me with the diagnosis. So for instance, I always take a clipping of a fingernail, an involved toenail, or both to rule out other diseases that can look similar to nail psoriasis, such as onychomycosis. Now, if I see a clipping with histopathology that shows hyphae, I immediately know it’s not nail psoriasis, and if I do a clipping with histopathology and there’s no hyphae, sometimes I can see parakeratosis and an infiltration of neutrophils, and that would help seal the deal that this is nail psoriasis.

Now, in terms of other tests or imaging, I do get hand X-rays on the majority of my nail psoriasis patients whether or not they’re complaining of joint pains, and that’s because in our cohort study of 87 nail psoriasis patients, about 10 percent had psoriatic arthritis, so I think it’s always good to get baseline X-rays to rule out joint involvement. But there is something new—we recently did a prospective study looking at nail psoriasis patients versus healthy controls using video capillaroscopy. So we used this device on the proximal nail fold, and we saw some findings that distinguished nail psoriasis patients from healthy controls, and this was decreased capillary density and length. We also saw increased abnormal morphology, and this included branching, meandering, bushy and ramified and/or bizarre capillaries, and a greater number of avascular areas.

Now, I’m not saying that this video capillaroscopy can definitively make the diagnosis of nail psoriasis, but certainly, combined with clinical examination and a clipping with histopathology showing no hyphae, video capillaroscopy can be helpful in making the diagnosis, but we need larger studies to really confirm this data.

Announcer:
That was Dr. Shari Lipner discussing diagnostic considerations for nail unit psoriasis. To access this and other episodes in our series, visit Clinician’s Roundtable on ReachMD.com, where you can Be Part of the Knowledge. Thanks for listening!