What’s the underlying cause?
Pityriasis amiantacea (PA) is a rare inflammatory condition of the scalp associated with an underlying disease processes such as atopic dermatitis, psoriasis, tinea capitis, and seborrheic dermatitis.
Recent literature has also found an association with Staphylococcus aureus contributing to the pathogenesis. Patients will present with dense scale adherent to the scalp and the proximal hair shaft. Temporary or scarring alopecia may be present or may develop as a result of PA.1
Case Report & Findings
A 25 y/o white woman presents to the dermatology clinic with a chief complaint of hair loss for the past 2 years. She reports, “itching and scabs” of the scalp and has not tried any treatment.
She is otherwise healthy and does not take any medications. The patient had no history of cutaneous psoriasis or fungal infections. Her family history is noncontributory.
The exam findings reveal adherent dense patches of silver scale on the scalp with asbestos-like scale to the proximal hair shaft covering roughly 40% of her scalp. There is associated hair thinning. Additionally, there is no evidence of any cutaneous lesions, but the patient does have pitting of the fingernails.
Differential Diagnoses
Psoriasis. The scalp is one of the most common sites for psoriasis. It presents in this area with discrete, well-defined plaques and can be associated with temporary hair loss. Skin, nails and joints can also be affected.2
Seborrheic dermatitis. This condition is a chronic mild eczema typically found in areas of high sebum productions like the scalp, face, ears, central chest, and intertriginous zones. Overproduction of sebum and the commensal yeast Malassezia furfur are linked in its pathogenesis.2
Atopic dermatitis. Atopic dermatitis is a common skin condition that primarily affects children, but can persist or present in adulthood. Involvement of the scalp is common. Diagnosis includes intense pruritus and acute, subacute or chronic eczema. Some of the other associated clinical features include: keratosis pilaris, hyperlinear palms, ichthyosis and pityraisis alba. Patients also often experience allergies and asthma.3
Tinea capitis. Clinical presentations of tinea capitis can vary widely, ranging from mild scaling to painful nodules. This dermatophyte infection is most common in preadolescents, but can present in adults and the elderly. Temporary or permanent hair loss can result at the site of infection.4
Assessment/Plan
In this case, a shave biopsy of the scalp was performed to reveal that the underlying cause of PA was psoriasis. It should also be noted that there were no fungal elements seen on the biopsy specimen.
The author recommended that the patient cleanse the scalp daily alternating with over-the-counter medicated shampoos that contain salicylic acid and tar. The author prescribed fluocinolone 0.01% scalp oil to apply to the scalp each night and rinse in the morning. She was instructed to follow-up in 4 weeks.
At her return visit, the patient demonstrated significant improvement. The scale was no longer present, and she showed evidence of new hair growth. The patient will continue maintenance therapy with medicated shampoos daily and fluocinolone oil as needed for flares.
Discussion of PA
PA represents a unique clinical entity that presents as a reactionary pattern to inflammatory diseases of the scalp.
It is not difficult to diagnose clinically, since it presents with a typical clinical appearance. However, diagnosis of the underlying pathology is paramount in providing appropriate treatment. Therefore, it may be necessary to perform a scalp biopsy or KOH.
PA is seen more commonly in young adults and seems to affect women more than men. This condition is often associated with temporary hair loss, but can cause scarring alopecia if not treated in a timely and effective manner.1
There are no current guidelines for PA, but treatment should be aimed at the underlying condition.
References
1. Abbas MY, et al. Pityraisis Amiantacea: Its clinical aspects, causes, and Associations; a Cross Sectional Study. Amer J Dermatol Venereol.2013;2(1):1-4.doi:10.5923/j.ajdv.20130201.01
2. Bolognia JL, et al. Chapter title. In: Dermatology. 2nd ed. New York, NY: Mosby Elsevier; 2008; pages cited
3. Ring J, Alomar A, Bieber T. Guidelines for the treatment of atopic eczema (atopic dermatitis) Part II.
J Europ Acad Dermatol Venereol. 2012;26(9):1176-1193.doi:10.1111/j.146-3083.2012.04636.x
4. Wolff K, Johnson RA. Dermatophytoses of Hair. In: Fitzpatrick’s Color Atlas and Synoposis of Clinical Dermatology. 5th ed. New York, NY: McGraw-Hill; 2005: 707-712
