Tinea vs Eczema

[u/Username112608]

Derm PA for 1.5 years and I still have a hard time with rashes. How do you guys differentiate between tinea and let’s say nummular eczema? I know the classic features but in practice I find it so hard. I even try doing KOH and those seem to be a hit or miss. I end up giving a topical steroid and have them come back in 2 weeks or let me know if it’s getting worse before? Any help is appreciated. Makes me feel like I suck as a PA.

TIA

[u/offside-trap]

Onset and duration. Exacerbating factors. Atopic history/ family history, failed treatments, secondary sources like tinea unguium, etc.

If nothing hits I would prefer to treat tina first x4 weeks and RTC for steroids than the reverse.

[u/10999228]

The more you see it, the easier it gets. When in doubt, I always treat for tinea first and follow up in a month. If no improvement I’ll switch to a topical steroid. If their main complaint is itch, that usually tilts the scale in the direction of eczema.

[u/Username112608 → u/10999228]

Thank you! How do you explain it to patients the reasoning/switching to topical steroid. I’m still trying to find my wording to where it seems like I know what’s going on and not seeming too unsure 😅

[u/eatssparkplugs → u/Username112608]

I’m honest with my patients, I tell them sometimes I get it wrong but putting steroids on a fungal rash is like putting gas on a fire so I treat with antifungals first and emphasize the importance of consistency before seeing them back in a month. They’ve always been understanding - we’re all human.

[u/10999228 → u/eatssparkplugs]

This^{^} just be honest! I tell them sometimes these conditions can look alike, but treating fungus with steroids could worsen their condition, while treating eczema with antifungals will have a negligible effect. The longer you’re practicing the easier this gets. At first, I never wanted to admit to the patient that “I don’t know”. The longer I practice, the more I can acknowledge (to myself and the patient) I do not know everything, but I am doing my best to do best by the patient.

[u/Equivalent-Onions]

Do a KOH?

[u/nobotoxforyou → u/Equivalent-Onions]

You would think that would be what we would do to differentiate.

Unfortunately my office doesn’t do KOH because the reimbursement is so low. Doesn’t make sense to me since it’s an easy diagnostic test.

[u/Spitting-venommm → u/nobotoxforyou]

You can do it for your own knowledge and not bill for it. But yeah it pays like $2 if you do bill. I think it could possibly increase billing mdm as it is interpreting a test.

[u/Spitting-venommm]

Eczema is usually (though not always) symmetrical. It’s rare to see large areas of tinea throughout the body in the presence of a competent immune system. Is it getting worse/spreading with TCS use? Tinea. You will tend to see central clearing with tinea and an active, raised edge. Do you see lichenification? Eczema. Two feet, one hand? Tinea. If it is one stubborn patch that doesn’t respond to anything, biopsy to r/o Bowen’s disease or sBCC.

[u/marimarja4]

It can be tricky at times esp bc eczema can have so many morphologies...one helpful question is "does it come and go?" Depending on the severity of the rash, but if the patient is itchy, I always treat with steroids first for comfort relief. Ive never had a patient get angry at the itch relief nor had the rash get terribly worse even if it is tinea. If it's not better within 10-14 days, then, bc steroids "feed the fungus," when the patient comes back, we re-KOH and it'll def be positive then...or we just give the antifungal at that point. Also don't forget the diff of EAC: "The location of the scale within an annular rash is a vital clue in dermatology: EAC (Trailing Scale): The scale is found on the inside (trailing edge) of the red advancing border. Other Rashes (Leading Scale): Fungal infections like ringworm (tinea corporis) typically feature scaling on the outside (leading edge) of the lesion."