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Diagnosing Rosacea

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Obtaining a diagnosis for rosacea may seem to be fairly straight forward but considering that there are reports of misdiagnosis it would be good for rosaceans to be educated on this subject so that if one experiences a misdiagnosis it will not be a surprise and will understand better how a diagnosis is obtained. A recent survey by Galderma/NRS says that the results “highlight the low awareness and complicated diagnosis path for this common condition.”

Generally, one diagnostic differentiator is when treatments for acne exacerbate the problem, this is used as an indicator in a diagnosis of rosacea. Rosacea is sometimes referred to as  'adult acne' in older papers, later called 'acne rosacea' and because it looks like acne. Rosacea is generally adult onset, and older adults obtaining a rosacea diagnosis is common. However, there are rare reports of children receiving a diagnosis of rosacea.

First and foremost is that diagnosis is the sole prerogative legally and ethically of a physician. So the information in this editorial is not meant to substitute or replace a physician’s diagnosis but is simply for a rosacea sufferer to understand the subject of a rosacea diagnosis for educational purposes. Knowing what is involved in obtaining a diagnosis of rosacea is quite helpful in basic Rosacea 101 which is a subject I am quite familiar with and wish to pass on this information freely to those who wish to increase their rosacea knowledge. When you read in rosacea social media groups the common question, 'IS THIS ROSACEA?' asked to a group of rosacea sufferers by posting photos of your face, do you really think that this group is qualified to differentiate rosacea from this list? However, learning how a diagnosis of rosacea is obtained by a physician can be rewarding and help you better to ask pertinent questions to your dermatologist. 

There is no histological, serological or other diagnostic tests for rosacea and a diagnosis is simply arrived at by a patient history and physical examination. [1] Some clinical tests may be done, i.e., blood tests, skin biopsies, scans, etc., to rule out rosacea mimics or other diseases, not to mention ruling out nay co-existing conditions. There are now certain devices recommended to be more objective in diagnosing rosacea. [12]

The NRS Classification System (2002) into subtypes and one variant is the first clearly defined proposal to identify and classify rosacea. [2] It is of interest to note that this classification system is based on morphology rather than causality. Understanding this classification and variant system was the beginning of a better understanding for this disease, however, it has been controversial from the beginning. Dermatologists who are still using the subtype classification system are somewhat able to better diagnose rosacea and it may be that your physician is familiar with this old classification, however, some physicians are not keeping up with this latest classification system and may be relying on past knowledge on this subject when referring to subtypes. If your physician is still referring to subtypes, you may want to point out the next paragraph to your physician. 

Phenotype Classification of Rosacea
The new direction of classifying rosacea is a phenotype based treatment

Physical Examination, History & Tests

Does rosacea spread beyond the facial region?

Frank Powell, MD, who served on the NRS ‘expert committee‘ that classified rosacea says in his book, “There is no laboratory test or investigation that will confirm the diagnosis of PPR. Specific investigations may be required to rule out similar appearing conditions (many of which will be identified by listening carefully to the patient’s medical history and examining the skin lesions). These include skin swabs for bacterial culture, skin scrapings for the presence of demodex mites, scrapings for fungal KOH and fungal culture, skin biopsy for histologic examination, (and rarely culture) skin surface biopsy for demodex mite quantification, patch tests, photopatch tests, and very rarely systemic workup with appropriate blood tests and radiological examinations.” [3]

To rule out demodectic rosacea “Potassium hydroxide examination, standardized skin surface biopsy, skin biopsy, or a combination of these are essential to establish the diagnosis.” [4] However, some researchers state that  if you use a skin scraping with a light microscope, there may be no reliable data on demodex density counts. However when using a 'Confocal laser scanning in vivo microscopy', there is a significantly more reliable data to count on simply using a skin scraping with a microscope. [11]

In some cases to rule out rosacea mimics such as lupus and scleroderma it is suggested that obtaining an ANA blood test and other blood tests might be considered. [5] Another test you might consider having is the Autologous serum skin test (ASST) to rule out chronic uticaria.

One report says it is necessary to perform individual bacterial cultures and antibiograms on rosacea patients. [6]

Another report suggests testing mucin to differentiate lupus. [7]

Another test to consider is to rule out Grave’s disease with blood tests. According to Ladonna, “…my husband took me to the dermatologist and she said it was Rosacea and couldnt be anything but….So he took me to many doctors, and finally a wonderful doctor took a shot in the dark blood test and discovered my problem. Later more involved tests and scans confirmed it. I was Hyperthyroid…specifically Graves Disease…”

So from the above tests it shows that a five minute visit to your dermatologist who simply diagnoses you with rosacea and doesn’t take any of the tests mentioned above to differentiate other rosacea mimics might mean you could receive a misdiagnosis. There is anecdotal evidence that many rosaceans report a quick diagnosis in five minutes or less.

Galderma has patented a diagnostic test for rosacea

Taking a Patient History and Biopsies

In Powell’s last chapter, [3] entitled, General Considerations, he suggests asking questions to the patient in taking a history, specifically:

(1) Asking about polycythemia?

(2) Whether the patient has been using a steroid cream?

(3) Any other medication such as niacin or antacids?

(4) Whether there has been any frequent flushing?

(5) Any complementary or alternative medicines, i.e., herbal products?

(6) Eye symptoms?

(7) Any family history of rosacea?

Biopsies to rule out demodectic rosacea is another important consideration. One report suggests a biopsy to rule out Morbus Morbihan.

If you physician neglects to ask any of the above questions you might simply bring the above questions to his attention in a respectful tone so that a proper diagnosis of your skin condition can be obtained. Not knowing the answers to the above questions may hinder a proper diagnosis.

Rosaceanet (ADD) has 15 questions to ask you and then recommends something to you if you would like more info on a diagnosis. [8] If you note the disclaimer it says, "This questionnaire does not provide medical advice. It should not be used to diagnose rosacea. Only a medical doctor such as a dermatologist can make this diagnosis. The purpose of this questionnaire is to help you seek medical care if you believe that you may have rosacea. A dermatologist can provide you with a diagnosis and proper treatment."

As more information on diagnosis is discovered that is pertinent to this article it will be updated.

Dermoscopy and Other Tools to Detect or Quantify Demodex Density Counts

Dermoscopy may prove useful according to this source:

"Dermoscopy, in addition to its well-documented value in evaluation of skin tumours, is continuously gaining appreciation also in the field of general dermatology." [9] "The dermoscopic hallmark of rosacea is represented by the presence of linear vessels characteristically arranged in a polygonal network (vascular polygons) {click for image}." [10]

Scroll down to the subheading, Tools to Detect or Quantify Demodex Density Counts, in the post, Demodex Density Count - What are the Numbers?

Non-Invasive Object Skin Measurement
A study recommends a more objective skin measurement for erythema, demodex density counts, rosacea severity, etc, using certain device tools. [12]

End Notes

[1] National Rosacea Society, Answer to Question 5

"There is no appropriate and reliable method of evaluating and monitoring severity in rosacea."
Nailfold capillaroscopy as a diagnostic and prognostic method in rosacea.
Fonseca GP, Brenner FM, Muller CD, Wojcik AL.
An Bras Dermatol. 2011 Feb;86(1):87-90.

[2] Classification of Rosacea

[3] Rosacea Diagnosis and Management by Frank Powell
with a Contribution by Jonathan Wilkin

[4] Demodicosis: a clinicopathological study.
Hsu CK, Hsu MM, Lee JY.
J Am Acad Dermatol. 2009 Mar;60(3):453-62

[5] Scroll to Alba’s Post #6 about ANA Blood Tests

[6] Necessary to perform individual bacterial cultures and antibiograms in rosaceans?

A new study on acne and rosacea patients concluded these findings:

1. In the cases of acne vulgaris the majority of isolated bacteria from conjunctival sac included Streptococcus spp., Staphylococcus spp. and Enterobacteriaceae.
2. In the severe cases of rosacea the main bacteria found in conjunctival sac were S. aureus, S.pyogenes, P.aeruginosa, E. faecalis, A. baumanii, P. fluorescens.
3. Because of changeable drug-sensitivity of bacterial strains, it seems to be necessary to perform individual culture and antibiogram in every patient with inflammatory lesions, in particular in clinically severe and resistant to therapy cases of acne vulgaris and rosacea.
4. The higher frequency of the bacterial colonisations in the conjunctival sac in patients with acne vulgaris and rosacea can be a potential source of ocular infections in the cases of local and systemic disorders of protective mechanisms.
5. Estimation of bacterial flora and antibiotic sensitivity of bacteria isolated from conjunctival sac, the skin of the eyelids and skin lesions should be perform, especially when patients are prepared for eye surgery.

Source of the above information

[7] Mucin is not a rare finding in rosacea is the title of a research study done by A. Fernandez-Flores at the Service of Cellular Pathology, Clinica Ponferrada in Spain.



Mucins are a family of high molecular weight, heavily glycosylated proteins (glycoconjugates) produced by epithelial tissues in most metazoans. They are
being investigated for their potential as diagnostic markers.


The study concluded "that: 1. mucin is a common finding in granulomas of rosacea; 2. this mucin is probably not related to any progression to the mucinous variant of rhinophyma; 3. since discoid erythematosus lupus is a clinical differential of rosacea, it is important to be aware of the fact that
mucin is a common finding in the granulomas, in order not to misdiagnose both entities."

Here is another potential diagnostic marker to differentiate rosacea from lupus.

[8] Rosaceanet
American Academy of Dermatology
Could I Have Rosacea?

[9] J Eur Acad Dermatol Venereol. 2013 Mar 12. doi: 10.1111/jdv.12146. [Epub ahead of print]
Dermoscopic patterns of common facial inflammatory skin diseases.
Lallas A, Argenziano G, Apalla Z, Gourhant JY, Zaballos P, Di Lernia V, Moscarella E, Longo C, Zalaudek I.

[10] Dermatol Ther (Heidelb). 2016 Dec; 6(4): 471–507.
Published online 2016 Sep 9. doi:  10.1007/s13555-016-0141-6
PMCID: PMC5120630
Dermoscopy in General Dermatology: A Practical Overview
Enzo Errichetti, Giuseppe Stinco

[11] Russian Study on Demodex Mites and Rosacea Illuminating

[12] Br J Dermatol. 2019 May 23;:
Non-invasive objective skin measurement methods for rosacea assessment: a systematic review.
Logger JGM, de Vries FMC, van Erp PEJ, de Jong EMGJ, Peppelman M, Driessen RJB

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