Chapter 207 Seborrheic Dermatitis
Diagnostic Summary
• Branny or greasy scaling over erythematous skin patterned on the sebum-rich areas of the scalp, face, and trunk. Facial areas include the forehead, eyebrows, eyelashes, nasolabial folds, and beard. Truncal involvement includes the presternal region, umbilicus, axillae, inframammary and inguinal folds, and perineum.
• The scalp appearance varies from mild, patchy dandruff to widespread, thick, adherent crusts; it may involve the anterior and posterior hairline and the periauricular skin. In infants it occurs as “cradle cap.”
• Usually nonpruritic, although active phases can manifest with burning and itching.
General Considerations
Malassezia yeast organisms are probably not the cause but a cofactor linked to depressed helper T cells (seborrheic dermatitis is very common in AIDS); increased natural killer cells, which increase inflammatory cytokines; increased sebum levels; activation of the alternate complement pathway; and genetic susceptibility to a skin barrier dysfunction.1 Malassezia species have lipase activity, which releases inflammatory arachidonic acid. Seborrheic dermatitis is aggravated by changes in humidity, scratching, emotional stress, diet, various medications, and androgen excess.
Therapeutic Considerations
Nutrition
Food Allergy
Seborrheic dermatitis usually begins as cradle cap and, although not primarily an allergic disease, has been associated with food allergy (67% of patients exhibit some form of allergy by 10 years of age).2
Biotin
The underlying factor in infants may be a biotin deficiency.3 A syndrome clinically similar to seborrheic dermatitis has been produced by feeding rats a diet high in raw egg white (high in avidin, a glycoprotein that binds biotin, making it unavailable for absorption). Because a large portion of the human biotin supply is provided by intestinal bacteria, it has been postulated that the absence of normal intestinal flora may be responsible for biotin deficiency in infants.2 A number of articles have demonstrated successful treatment of seborrheic dermatitis with biotin in both the nursing mother and the infant.3,4
In adults, treatment with biotin alone is usually of no value.
Pyridoxine
Both the administration of desopyridoxine, which induces pyridoxine deficiency in humans, and the placing of rats on a pyridoxine-deficient diet cause dermatologic lesions indistinguishable from seborrheic dermatitis.5 Despite these results, oral and parenteral applications of pyridoxine have shown little success. However, in the sicca form of the disorder (involvement of the scalp [dandruff], brow, nasolabial folds, and bearded area with varying degrees of greasy adherent scales on an erythematous base), all cases cleared completely within 10 days of local application of a water-soluble ointment containing 50 mg/g of pyridoxine. Other types of seborrheic dermatitis, particularly flexural and infected, did not respond to this mode of therapy.
In one study of patients with elevated levels of urinary xanthurenic acid, oral, parenteral, and local applications of pyridoxine all returned excretion levels to normal, implying transcutaneous absorption of pyridoxine.5,6 These results are clouded, however, by those of another study indicating that the improvement from topical application may be due more to reduction in sebaceous secretion rate by the ointment itself, the added pyridoxine having no effect.7
The patient should be checked for exposure to pyridoxine antimetabolites. Examples are the hydrazine dyes (U.S. Food Drug and Cosmetic Act [FD&C] yellow no. 5) and drugs (isoniazid and hydralazine), dopamine, penicillamine, oral contraceptives, and excessive protein intake.8
Botanical Medicines
Aloe vera
Aloe vera gel can be quite helpful when applied topically. In one double-blind trial in people with seborrheic dermatitis, the application of a 30% crude aloe emulsion cream twice a day for 4 to 6 weeks produced improvements in scaling and itching in 62% of subjects compared with improvements in only 25% of the placebo group.9
Melaleuca alternifolia
M. alternifolia (tea tree) oil has demonstrated activity against Malassezia species, which may be of benefit in the treatment of seborrheic dermatitis. Honey and cinnamic acid have similar activity.10 A study of 126 patients using 5% tea tree oil shampoo showed 41% improvement in severity versus 11% in the placebo group.11 Tea tree oil may be added to the patient’s favorite shampoo as a way of increasing compliance.
Homeopathic Therapy
A 2002 study evaluated the efficacy of a homeopathic combination remedy in the control of seborrheic dermatitis and chronic dandruff. The homeopathic therapy of Kali brom 1x, Natrum brom 2x, Niccolum sulf 3x, and Natrum mur 6x (potassium bromide, sodium bromide nickel sulfate, and sodium chloride) was studied in a placebo crossover trial in 41 patients with seborrheic dermatitis and/or chronic dandruff. At the end of 10 weeks, all patients crossed over to the active medication under a different label for an additional 10 weeks in an open-study format. Twenty-nine patients completed the 10-week blinded portion of the study. After 10 weeks of treatment, the disease state of the patients receiving active medication showed significant improvement compared with that of the patients receiving placebo (P < 0.04). Ten weeks after crossover, the placebo patients experienced improvement as well (P < 0.01).12
Therapeutic Approach1. Faergemann J., Bergbrant I.M., Dohse M. Seborrheic dermatitis and Pityrosporum folliculitis: characterization of inflammatory cells and mediators in the skin by immunohistochemistry. Br J Dermatol. 2001;144:549–556.
2. Eppig J.J. Seborrhea capitis in infants: a clinical experience in allergy therapy. Ann Allergy. 1971;29:323–324.
3. Nisenson A. Seborrheic dermatitis of infants and Leiner’s disease: a biotin deficiency. J Pediatr. 1957;51:537–548.
4. Nisenson A., Barness L.A. Treatment of seborrheic dermatitis with biotin and vitamin B complex. J Pediatr. 1972;81:630–631.
5. Schreiner A., Slinger W., Hawkins V., et al. Seborrheic dermatitis: a local metabolic defect involving pyridoxine. J Lab Clin Med. 1952;40:121–130.
6. Callaghan T. The effect of folic acid on seborrheic dermatitis. Cutis. 1967;3:584–588.
7. Andrews G.C., Post C.F., Domonkos A.N. Seborrheic dermatitis: supplemental treatment with vitamin B12. N Y State J Med. 1950;50:1921–1925.
8. Schreiner A., Rockwell E., Vilter R. A local defect in the metabolism of pyridoxine in the skin of persons with seborrheic dermatitis of the “sicca” type. J Invest Dermatol. 1952;19:95–96.
9. Effersoe H. The effect of topical application of pyridoxine ointment on the rate of sebaceous secretion in patients with seborrheic dermatitis. Acta Derm Venereol. 1954;3:272–278.
10. Gupta A.K., Nicol K., Batra R. Role of antifungal agents in the treatment of seborrheic dermatitis. Am J Clin Dermatol. 2004;5(6):417–422.
11. Satchell A.C., Sauragen A., Bell C. Treatment of dandruff with 5% tea tree oil shampoo. J Am Acad Dermatol. 2002 Dec;47(6):852–855.
12. Smith S.A., Baker A.E., Williams J.H. Effective treatment of seborrheic dermatitis using a low dose, oral homeopathic medication consisting of potassium bromide, sodium bromide, nickel sulfate, and sodium chloride in a double-blind, placebo-controlled study. Altern Med Rev. 2002;7:59–67.
13. Messaritakis J., Kattamis C., Karabula C. Generalized seborrhoeic dermatitis: clinical and therapeutic data of 25 patients. Arch Dis Child. 1975 Nov;50(11):871–874.
