Decoding skin of colour: How melanosome and ceramide variations influence dermatologic pathology
Understanding unique structural and biochemical differences in skin of colour is key to accurately diagnosing and treating derm conditions in diverse populations (Issue #500, 1,600 words, 8 minutes)
Differences in pigment cells and lower levels of ceramides in Black or Brown skin lead to different skin behaviours in these patients, Dr. Archana Kakadekar told delegates to the first annual Indigenous Skin Spectrum Global Summit on April 5 in Montreal. That included elevated rates of post-inflammatory hyperpigmentation, severe scarring, and a tendency towards drier skin and increased itch.
Dr. Kakadekar is an anatomical pathologist subspecializing in dermatopathology and breast pathology. She recently finished her one-year fellowship in dermatopathology in Halifax and began her practice this past August in Saskatoon. Her interests include transgender medicine in the field of clinical and anatomical pathology, as well as skin of colour in anatomical pathology.
She said differences in skin colour are not due to variations in the number of melanocytes but rather the size, the amount and the distribution of melanosomes within the melanocytes. Fitzpatrick skin phototypes three to six contain larger melanosomes that are individually dispersed, while phototypes one and two tend to have smaller melanosomes in aggregates.
Studies have shown that in Brown and Black skin, there is increased production, size and density of melanosomes, smaller collagen fibre bundles, a compact stratum corneum with increased layers, and larger dermal fibroblasts, said Dr. Kakadekar. There are fewer ceramides, which leads to increased transepidermal water loss. This is a key factor in why patients with phototypes three to six may present with increased dryness and pruritus. East Asian skin was found to have a thinner stratum corneum, increased ceramides, and a weaker skin barrier, which leads to increased sensitivity.
Post-inflammatory hyperpigmentation is more common in patients with phototypes three and higher, said Dr. Kakadekar. This happens due to either exogenous or endogenous trauma. The body reacts by stimulating melanocytes to produce more melanin as a protective mechanism. The melanin can then drop out from the base of the epidermis into the dermis. It may not be possible to delineate the pathogenesis of the hyperpigmentation through biopsy, making the clinical history very important.
Keloids or hypertrophic scars are usually an obvious clinical diagnosis, and are 10 to 15 times as common in Black or Brown skin, said Dr. Kakadekar. The scars are caused by an irregular fibroproliferative production of atypical collagen bundles as a reaction to trauma to the skin.
Awareness of the variable presentation of common skin conditions in patients of colour is essential for clinicians and pathologists.
Bottom Line: Patients with Black or Brown skin have fewer ceramides in their skin, which leads to increased transepidermal water loss. This contributes to increased dryness and pruritus in phototypes three to six. East Asian skin was found to have a thinner stratum corneum, increased ceramides and a weaker skin barrier, which leads to increased sensitivity. Post-inflammatory hyperpigmentation, as are keloids, is more common in patients with darker skin.
From the literature on dermatology in skin of colour
Ablative CO2 laser treatment of rhinophyma in people of colour: A case series
The authors of this paper note that while rhinophyma is rarer in patients with skin of colour, it does occur. However, less is written in the literature about the limits of laser treatment for the condition in these populations.
They present a case series of seven patients with Fitzpatrick skin types three to five and moderate to severe rhinophyma treated with CO2 laser excision. The patients were followed for six months postoperatively. The seven experienced significant improvement in nasal appearance and functional nasal obstruction.
Three patients in the series developed some scarring in the supratip and tip region that did not significantly deter the overall improvement in nasal aesthetics from treating the disease.
The authors conclude that a more conservative treatment plan concerning the depth of resection may have limited scarring, or perhaps the traditional teaching to approach laser treatments in patients with melanated skin with caution due to the risks of scarring is supported here.
Increased melanin induces aberrant keratinocyte-melanocyte-basal-fibroblast cell communication and fibrogenesis by inducing iron overload and ferroptosis resistance in keloids
Researchers investigated the role of melanocyte-secreted melanin in promoting fibroblast fibrogenesis and its mechanism and evaluated the potential therapeutic effect of intervening melanin in treating keloid.
Investigators examined the activity of pigmentation-related pathways in keloid melanocytes in human cell samples and in a mouse model.
They found increased melanin levels in keloid patients. Melanin positively correlated with the Keloid Area and Severity Index. Furthermore, melanocyte-secreted melanin significantly promoted fibroblast proliferation, migration, and collagen synthesis. Mechanically, melanin increased basal cell permeability and inflammation to facilitate its transfer to the dermis, where it further activated fibroblasts by evoking iron overload and ferroptosis resistance.
Researchers also consistently validated iron overload and ferroptosis resistance in primary fibroblasts and skin tissues of keloid patients.
When the investigators inhibited iron overload and ferroptosis resistance, it effectively diminished melanin-induced fibrogenesis.
In the mouse model, delivery of ML329, a microphthalmia-associated transcription factor (MITF) inhibitor, suppressed melanogenesis and alleviated keloid in human keloid-bearing nude mice. Meanwhile, ML329 decreased the iron content and restored the sensitivities of ferroptosis.
They concluded that melanin-lowing strategies may be a potential new therapeutic target for keloid.
Sunscreens in pigmentary disorders: time to revise the message
This paper's authors note that darker skin is believed to be better protected against UVB, so sun-protection messaging has been primarily targeted at people with lighter skin tones. This is reflected by low sunscreen use by people of darker skin types, they note.
However, they write there is a growing appreciation of visible light as a culprit behind the exacerbation of disorders of hyperpigmentation, such as melasma and post-inflammatory hyperpigmentation.
Because the role of visible light in melanogenesis is not well known to patients or dermatologists, there is a missed opportunity in managing pigmentary disorders, they say.
The authors advocate for inclusive sunscreen messaging that addresses the needs of people of all skin colours. They say that dissemination of the role of sunscreen beyond skin cancer prevention is likely to be pivotal, and transitioning from the term ‘sunscreen’ to ‘light protection’ may help facilitate this change.
VIDEO: Can we use lasers for dark skin?
Dr. Nadir Qazi, a cosmetic dermatology surgeon in Newport Beach, Calif., discusses laser treatment of acne scars, pigmentation, and melasma in darker skin types.
At the intersection of skin and society
This Wednesday, June 25, Toronto is hosting the World Vitiligo Day 2025 Innovation Summit.
Advocates, clinicians, researchers, and patients from around the world are preparing for World Vitiligo Day 2025. The Summit, which will be held at the MaRS Waterfront in Toronto, is an event dedicated to advancing awareness, research, and support for people living with vitiligo. The conference will blend scientific innovation, patient advocacy, and community spirit for patients with vitiligo.
Registration is now open for in-person and online participation, with organizers anticipating over 100 on-site attendees and more than 200 virtually joining. The event, co-hosted by Vitiligo Voices Canada (VVC) and the Vitiligo Research Foundation (VRF), is supported by Incyte.
The 2025 conference is designed to foster collaboration and inspire new approaches to vitiligo care. Attendees can expect a dynamic agenda featuring clinical insights from leading medical experts, cutting-edge research presentations, and discussions on emerging technologies—including artificial intelligence in the diagnosis and treatment of vitiligo. Patients will be able to share their stories and experiences in a safe, welcoming environment.
“This is more than just a conference—it’s a movement,” says Shahnawaz Towheed, a medical student at McMaster University in Hamilton and co-founder of Vitiligo Voices Canada. “We’re bringing together the best minds in healthcare, technology, and advocacy to drive real change for people living with vitiligo.”
Beyond the scientific program, World Vitiligo Day 2025 will emphasize the diversity and resilience of the vitiligo community. Attendees will have the chance to network with peers, discover breakthroughs in care, and experience the intersection of art and artificial intelligence through creative showcases. The event will also spotlight the #Lit4Vit campaign, which sees landmarks around the world illuminated in purple to raise awareness and promote understanding of vitiligo.
Readers of Skin Spectrum Weekly can register at www.worldvitiligoday.ca. The Summit will take place at the MaRS Waterfront, Lake Lounge (155 Queens Quay East, Toronto, Ont. M5A 1B6) from 7:30 a.m. to 5:30 p.m. EDT on June 25. A global livestream of the event will also be available for those unable to attend in person.
“We are at a pivotal moment in vitiligo care,” says Towheed. “By coming together—clinicians, patients, advocates, and supporters—we can build a future where every person with vitiligo feels seen, heard, and empowered.”
For more information and to register, visit www.worldvitiligoday.ca
This week
June 25 is World Vitiligo Day
June 27 is Canadian Multiculturalism Day
June 29 is International Day of the Tropics
Something to think about in the week ahead . . .
—LaMelo Ball, (2001 – present), U.S. athlete
500th issue survey
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Next week
Barrie, Ont.-based dermatologist Dr. Megan MacGillivray discusses differences in the appearance of basal cell carcinomas in skin of colour and the value of dermoscopy for diagnosis.
If you enjoy Skin Spectrum Weekly, why not check out the Chronicle’s other publications, podcasts, and portals?
Established in 1995, The Chronicle of Skin & Allergy is a scientific newspaper providing news and information on practical therapeutics and clinical progress in dermatologic medicine. The latest issue features:
Dr. Robert Micheletti (Philadelphia) reviews the current science on the diagnosis and treatment of vasculitis.
Drs. Gurbir Dhadwal (Surrey, BC), Jeff Donovan (Whistler, BC), and Renée Beach (Toronto) discuss new treatments for alopecia areata.
Drs. Ben Barankin (Toronto), Jaggi Rao (Edmonton), and Jason Rivers (Vancouver) provide an update on managing rosacea in 2025.
Plus regular features, including the popular column “Vender on Psoriasis” by dermatologist Dr. Ron Vender.
You can read a recent digital edition of The Chronicle of Skin & Allergy here. To apply for a complimentary subscription or to request a sample copy, please email health@chronicle.org with your contact information.
The Women in Dermatology e-newsletter updates readers with new findings concerning dermatologic issues affecting women and the female dermatologists who care for them. Read the current issue here.
Season three of the Vender on Psoriasis podcast with Dr. Ron Vender has begun. Listen to the new season here. In episode five, Dr. Vender discusses whether vitamin D influences the severity of psoriasis, sex differences in psoriatic inflammation and itch, and the risk of psychiatric disorders associated with acitretin.
And if you’re looking for a web destination for all things derm, visit derm.city, “Where Dermatology Lives.” Please like, rate, review, and share it with your colleagues.
SO powerful! Thank you for drawing attention to this.