Riehl’s Melanosis

My UnderstandingOf Reihl’s Melanosis; including treatment options.

Reihl’s melanosis is a traditional name given to this pigmentary condition in 1917. It has been thrown around for well over a century for a condition that is not classified as other known conditions that give pigmentation, & it may be associated with contact dermatitis (allergens). 

Here are my thoughts- if an allergen is found that can give rise to post-inflammatory hyperpigmentation AND that can be explained by the distribution of pigment in the patient, the name should not be called Reihl’s melanosis, it should be contact dermatitis with PIH or pigmented contact dermatitis. This is why a medical dermatologist should be involved in this case. They need to exclude other causes of pigment; lichen planus pigmentosus may look like Reihl’s. The histology is similar, but the pattern is unique (if classical), namely LPP may affect the scalp & oral mucosa (frequently the mouth). A medical dermatologist can exclude atypical acanthosis nigricans (it’s more common than you can imagine) as well as atypical cases of melasma, & other autoimmune disorders. 

For the cases that do not fit a distinct classification, the NFI classification of dermal pigment is then termed ADMH or acquired dermal macular hyperpigmentation). Confusingly this may encompass LPP, Ashy, as well as idiopathic macular hyperpigmentation (this, IMO is easier to diagnose as the patches are smaller, concentrated on the trunk, with less facial involvement).

Here is the pathway to management of Reihl’s & other forms of unusual pigmentation. 

1. Get a good medical dermatologist involved early in the course of diagnosis. This gives a clear pathway to manage. Remember I am only involved in the laser- pigment removal side of things. 
2. Get allergy testing if indicated. Have a crystal clear understanding of allergens involved before seeing me. 
3. Understand photoprotection & practice this before seeing me. 
4. Understand that lasers are hit & miss. My team & I will apply the very latest technology, acknowledging that failure rates are high. Understand your financial commitment prior to embarking on your laser journey. 

Allergy testing & Reihl’s Melanosis

In the ideal world, you should have patch testing before seeing me. If you have an allergen, avoiding these will make your laser treatments more efficient & effective (though not guaranteed). If your immune system is activated by an allergy, your skin’s barrier function ie. the basement membrane which holds the pigment which normally sits in the upper layers of the skin is compromised. This leads to pigment drop out (pigment in the dermal layer of skin). 

Lasers can partially treat dermal pigment, but if you still have allergen, it is like pissing in the wind. If you do have patch testing, get it done by a dermatologist who has interest in allergy testing. Ideally we want you tested with the European Standard Battery in addition to your current cosmetics. Having excluded allergens will make my team (& me) much more effective with lasers. In Brisbane, see my colleagues at Cutis Dermatology, in Sydney you will be referred to the Skin Hospital. 

Photoprotection & Reihl’s Melanosis

Please get this right before seeing myself. In truth over 90% of patients that I see for pigmentary disorders have not even stepped foot on FIRST base. Yes, I know that you, like myself, are ethnic, we don’t burn easily, we do not get skin care (rarely). That’s not the point. The point is that pigmentary disorders such as melasma, post inflammatory hyperpigmentation, Ashy dermatosis, Reihl’s & drug induced causes are exacerbated by radiation, not just UV. 

Before wasting thousands of dollars on pico lasers for Reihl’s, get your sun protection right. I understand that the literature suggests the action spectrum of Reihl’s is UV only (UVB & UVA), however I suspect that it extends to the visible light spectrum. This means you need iron oxide to protect against blue or high energy visible light. 

Here is the rundown of sunscreen (do this before seeing me as I don’t want to spend 10 minutes of the consultation talking about sun exposure & sunscreen use). 

1. Use a tinted SPF 50 + sunscreen.
2. Use it twice a day, regardless of sun exposure. You can not predict when you will go outside. If you see light, you are not protected, and no, you do not ‘stay home all day’.
3. Use two finger lengths of sunscreen per application. 
4. One 50 ml bottle should last 3 weeks. 
5. Find a color that suits you, a cheap tinted sunscreen that is not color matched looks ridiculous, meaning you won’t wear it, so find one that you WILL use.

Lasers & Reihl’s Melanosis

Despite huge advances in laser technology, quite frankly, treatment is still hit & miss, even when it comes to pico lasers. Failure rates can be explained by deep dermal pathology (out of reach from lasers), missing an exogenous allergen (hence why I prefer a through patch testing by a medical dermatologist), patient factors (most important is radiation exposure) & as an excuse if all else fails, we still do not understand this disease. You will be counseled repetitively that lasers, despite their advancements in technology, are not guaranteed for the management of Reihl’s. 

3 types of lasers are employed for Reihl’s

Pico lasers, either Picoway or Picosure are employed. Pico lasers are only used if Reihl’s is stable, namely if the pathology shows pigmentation in the absence of vacuolar interface changes. I will review your pathology with your medical dermatologist. If you have active disease or if I suspect that patch testing is required, you will be referred accordingly. 

Pico lasers are hit & miss. The efficacy rate is around 40-50%, you will require 4-10 sessions, improvements are best after 12 to 18 months. To keep costs down, you will be treated by my clinical team. Resistant cases are treated by myself with higher power. This is not considered until you complete a course of low power settings (typically 10 sessions). High power pico has higher risks, hence why I am involved. If you see my clinical team & side effects such as PIH occur, I end up seeing you anyway, hence why I perform higher power settings. Obviously you should be mindful of costs, risks & success rates.  

QSL or dermal toning lasers can be effective, however the results are slower compared to Pico. This can be considered in patients that fail pico. For international patients, this may be the laser of choice as most dermatologists will own this laser. It costs less than pico, hence why it is accessible to most. 

Thulium 1927  lasers. These lasers are great for non-melasma pigmentation, especially in lighter skin types. Though reported to help in Reihl’s melanosis cases, I do not prescribe this laser. Why? Because pico lasers are more effective with less side effects. 

I do not use RFM or radiofrequency microneedling to routinely treat Reihl’s, acknowledging that a 2022 paper in Korea has used this treatment successfully. It can be considered in patients that fail pico & or QSL lasers.