Yesterday, a young woman complained of a pruritic rash on her right foot that was unresponsive to an over the counter antifungal agent. Clinically, there were some dried vesicles and a few collarettes of scale on her instep, clinically appearing most like resolving dyshidrotic eczema.
‘Let me just do an exam to make sure it’s not athlete’s foot.”
“Why bother? It didn’t respond to antifungal medication?”
“You never know”, I responded. “I was taught that if a rash is scaly, scrape it for a KOH exam, and see if it’s a fungal rash. I cannot begin to tell you how many times I’ve been fooled one way or the other”
The KOH (I use Swartz-Lamkins stain) was clearly positive for branching hyphae and ketonconazole cream prescribed. I showed mother and daughter the slide. They couldn’t believe it.
I was not surprised by the results of a survey by Yadgar et al of board-certified dermatologists demonstrating how often dermatophyte infections are misdiagnosed clinically for other disorders, such as secondary syphilis, annular psoriasis, and pityriasis rosea. The authors presented 13 cases and participants answered “yes” or “no” as to whether or not they thought the rash was a fungal infection. In only 4 of the 13 cases did the audience members surpass 75% accuracy. The authors underscored the importance of bedside diagnostic techniques such as the KOH examination “during residency and beyond” to confirm the diagnosis of dermatophytoses (1).
I’m concerned about the KOH exam both in residency and beyond. Doing a KOH examination seems straightforward enough. Having taught residents for decades, I am convinced that it takes at least 6 months of practice to learn how to do it right. Little tricks such as moving the condenser down, lowering the light, gently focusing up and down, knowing that you are looking at hyphae instead of the edge of keratinocytes, and recognizing spores from small air bubbles takes practice. What concerns me more, however, is “beyond”. How many dermatologists have just given up on doing KOH examinations because of CLIA?
I have not given this much thought because I have high complexity CLIA (Clinical Laboratory Improvement Act of 1988) approval for dermatopathology. Twice a year I do a KOH certifying test from a lab. According to the Department of Health and Human Services (Centers for Medicare & Medicaid Services), the KOH examination is considered a moderately complex microscopy procedure. In order to perform a KOH smear, a certificate for provider-performed microscopy procedure (PPMP) is required.
If you are performing KOH examination without CLIA certification, you should be aware that there are criminal penalties for violating CLIA regulations including a year of imprisonment, as well as civil monetary penalties of $10,000 per day, and exclusion from federal programs.
I surmise that most dermatologists have given up on KOH exams, and I don’t blame them. I’d probably do the same rather than have another administrative hassle, take the time to do the exam, and get bubkes for reimbursement. So what are the options if you don’t do a KOH on skin, hair, or nails? You could do a scraping and send it to a certified lab for KOH and culture, perform a biopsy requesting a PAS stain, go “high tech” and order PCR (2) or perform reflectance confocal microscopy (3). My guess is that most practitioners will do none of the above and treat empirically, hoping that the patient gets better, as inevitably many will. Unfortunately, others will not because they do not have tinea!
We must be advocates for our patients. I have no data to back up my hypothesis, but after 3 decades of CLIA, we have probably taken a major step backward in the rapid, in-office diagnosis of dermatophyte infections. The rationale of implementing CLIA in the first place was because of the potential for life-threatening errors of reading Pap smears. Somehow this extended to myriad tests, including KOH examinations. (I am not making light of tinea infections – they can be nasty, but not fatal!). I am not opposed to having CMS consider the KOH a moderately complex examination. What I am against to is having board certified dermatologists who are trained in KOH examinations require CLIA certification; it would be appropriate for other non-dermatologist providers. Dermatologists should be exempt as this is what we do (or should be doing). I propose that a study be performed to survey dermatologists and ask the following questions: 1) Do you do KOH examinations in your office? 2) Are you CLIA certified? 3) If you are considering dermatophytoses, and do not perform KOH examinations, what tests do you obtain (if any)? My hypothesis is that CLIA certification for KOH examinations has been detrimental to our patients and has added to health care costs (in terms of misdiagnosis and obtaining more expensive tests) by dermatologists foregoing the procedure. I hope that such a study would prove me wrong, but I doubt that it will.
- Yadgar RJ, et al. Cutaneous fungal infections are commonly misdiagnosed: A survey-based study. J Am Acad Dermatol 2017; 76: 562-3.
- Robert R, Pihet M. Conventional methods for the diagnosis of dermatophytosis. Mycopathologica 2008; 166: 295-306.
- Turan E, et al. A new diagnostic technique for tinea incognito: In vivo reflectance confocal microscopy. Report of 5 cases. Skin Research & Technology 2013; 19: e103-7
*Image from OnlineDermClinic.com