Pellicules et dermatite séborrhéique

(Version Complète en Anglais)

General Concept, Prevalence and Incidence

Seborrheic dermatitis (SD) and dandruff are common dermatologic issues that affect the seborrheic areas of the body, share many of the same characteristics and respond similarly to treatments, so therefore can even be considered the same condition, only differing in terms of severity and location.
Dandruff occurs especially on the scalp, without presenting any usual signs of inflammation, but only through itchiness and the peeling of the skin (flakes). Dermatitis on the other hand, affects different areas of the body; from the face, to the retroauricular area (behind the ear) and the chest, where sometimes additionally presenting erythema, inflammation and the typical signs of scaly and peeling skin, associated with itching. The skin of dandruff is usually white/transparent and dry, whereas in DS it is usually of a yellow tone and oily.

Figure 1 – Seborrheic Dermatitis of the Scalp

Dandruff is the most common presentation and affects about 50% of the world’s population; it is more prevalent in men than in women and usually begins to present itself at puberty, with a peak of incidence and severity in the 20s and decreasing from the age of 50[i]. Its incidence varies among different ethnic groups, with indications that it is around 81 to 95% amongst African Americans, 66 to 82% amongst Caucasians and 30 to 42% amongst Asians/Chinese.

Differencial Diagnosis

The main differential diagnosis should include psoriasis, atopic dermatitis (especially in the pediatric form), tinea capitis, rosacea and systemic lupus erythematosus (SLE).

Diagnosis		Anamnesis
Psoriasis		It usually appears on the palms, soles, nails, knees, elbows, lumbar region, scalp and folded areas (although they can manifest in most any other part of the body, including affecting the joints).
Atopic Dermatitis		The first lesion usually occurs within the first 3 months, along with itchiness and agitation. It usually appears on the scalp, cheeks and behind skin folds. There is often a family history of atopy such as eczema, asthma and/or allergic rhinitis. Improvement usually occurs from age 12.
Tinea Capitis		It is the most common fungal infection in children and is easily transmitted. It appears on the scalp, the hair follicles and eyebrows. It can have the appearance of “black stump alopecia” due to split hairs near the scalp; areas of variable baldness, of defined and regular dimensions tending to converge, sometimes accompanied by smaller ones with a scaly surface or in the follicular or scaly erythematous form, thus having a scaly appearance close to that of seborrheic dermatitis.
Rosacea		It usually appears on the face. Papulopustules and telangiectasias in the malar, nose and perioral regions, with slight scaling. Recurrent edema and flushing.
Systemic Lupus Erythematosus		In the acute phase, a butterfly-shaped rash appears across the face sparing the tip of the nose or nasolabial folds. Photosensitivity is common. Skin lesions are usually associated with other clinical signs of SLE. Histology and serological tests such as antinuclear autoantibodies confirm the diagnosis.
Others	Pemphigus Foliaceous	Erythema, scaling and crusting, first present on the scalp and face, that may then spread to the chest and back. Histology, right immunofluorescence with anti-desmoglein antibodies confirm the diagnosis.
	Pityriasis Rosea	Abrupt onset, with the appearance of the ‘herald patch’ and resolution within weeks.
	Secondary Syphilis	Peripheral lymphadenopathy, mucosal lesions and palmoplantar macula-papules. Serological tests such as VDRL/RPR, FTA-ABS to confirm diagnosis.
	Diaper Dermatitis	It occurs on convex skin surfaces in contact with diapers, such as the lower abdomen, genitals, buttocks and upper thighs, though lesser in skin folds. Pustules are common.
	Langerhans Histiocytosis	Multisystem disease. Brown to purplish papules are likely to coalesce on the scalp, retro-auricular areas, axillae and inguinal folds. Possible lytic bone lesions, liver, spleen and lung involvement. Histology to confirm diagnosis.

Table 1 – Differential Diagnosis

Physiopathology

Dandruff and seborrheic dermatitis share many commonalities at the histological level, such as epidermal hyperplasia, parakeratosis and fungal involvement of Malassezia on parakeratotic cells[ii]. In seborrheic dermatitis there is usually the presence of inflammatory cells such as lymphocytes and NK, in dandruff there may be neutrophil infiltration or none at all, which may support the idea that dandruff and seborrheic dermatitis are part of the spectrum of the same disease with different severity and localization[iii].

Treatment

The treatment of dermatitis and dandruff should focus on eliminating the signs, improving the associated symptoms – especially the itchiness – and leading to a state of remission, even in the long-term.
Since the main and recognized pathogenic mechanism is the presence and proliferation of Malassezia, inflammation and local irritation, the most common treatments use topical antifungal and anti-inflammatory agents, tar-based soap/shampoo, lithium gluconate or succinate, phototherapy and more recently, topical applications of immunomodulators, such as calcineurin inhibitors and metronidazole.
More invasive therapeutic forms like corticosteroid and/or other drug use should be localized whenever possible.
In non-conventional therapies, the use of tea tree, washes with rosemary[iv] and the use of ozone therapy are very successful in eradicating symptoms and should be the first line of treatment, as they are mostly effective and highly safe.
In fact, the use of ozonated oil seems to be the best approach, either using ozonated oil for localized treatments or with shampoo and/or shower gel, because they improve the immune response[v], reduce the colonization of deleterious strains[vi], restore the skin’s microbiome[vii] and effectively eliminate the Malassezia responsible for dandruff, which is why it is an approach capable of eliminating the signs, improve the associated symptoms – especially itchiness – and lead to a state of remission.

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[i] Schwartz, JR.; Cardin, CW.; Dawson, TL. Seborrheic dermatitis and dandruff. In: Baran, R.; Maibach, HI., editors. Textbook of Cosmetic dermatology. London: Martin Dunitz, Ltd; 2010. p. 230-241.

[ii] Seborrheic Dermatitis and Dandruff: A Comprehensive Review. (2015). Journal of Clinical and Investigative Dermatology, 3(2). doi:10.13188/2373-1044.1000019

[iii] Schwartz JR, Messenger AG, Tosti A, Todd G, Hordinsky M, et al. A comprehensive pathophysiology of dandruff and seborrheic dermatitis – towards a more precise definition of scalp health. Acta Derm Venereol. 2013; 93:131–137. [PubMed: 22875203]

[iv] Borda LJ, Perper M, Keri JE. Treatment of seborrheic dermatitis: a comprehensive review. J Dermatolog Treat. 2019 Mar;30(2):158-169. doi: 10.1080/09546634.2018.1473554. Epub 2018 May 24. PMID: 29737895.

[v] Topical ozone therapies improve atopic dermatitis via rapidly reducing S. aureus colonization and immunoregulation. 13^thGlobal Dermatologists Congress July 23- 24, 2018 | Moscow, Russia

[vi] Ugazio E, Tullio V, Binello A, Tagliapietra S, Dosio F. Ozonated Oils as Antimicrobial Systems in Topical Applications. Their Characterization, Current Applications, and Advances in Improved Delivery Techniques. Molecules. 2020 Jan 14;25(2):334. doi: 10.3390/molecules25020334. PMID: 31947580; PMCID: PMC7024311.

[vii] Zeng J, Dou J, Gao L, Xiang Y, Huang J, Ding S, Chen J, Zeng Q, Luo Z, Tan W, Lu J. Topical ozone therapy restores microbiome diversity in atopic dermatitis. Int Immunopharmacol. 2020 Mar;80:106191. doi: 10.1016/j.intimp.2020.106191. Epub 2020 Jan 24. PMID: 31986325.