Psoriasis

Psoriasis is a chronic inflammatory dermatosis that presents with important clinical differences in individuals with darker skin tones. In a large cross-sectional study of more than 6,000 adults in the United States, the overall prevalence of psoriasis was estimated at 1.9 percent. Although prevalence was lower among individuals with darker Fitzpatrick skin types, these patients experienced greater disease severity and quality-of-life burden. This disparity may reflect delayed recognition, reduced access to dermatologic care, and higher rates of misdiagnosis. For example, patients with skin of color are diagnosed close to three years later than their White counterparts. 

Clinically, psoriasis in darker skin is characterized by less distinguishable erythema, which may appear violaceous, lilac, or gray rather than bright red, as well as thicker plaques, greater desquamation, and increased overall body involvement. Patients with darker skin tone, typically have between 3-10% total body surface area involved, where as there is only 1-2% body surface area affects in lighter skin tone patients. Scalp involvement is also more common among Black patients and may differ in appearance compared with lighter skin types.  

Dermoscopic evaluation can assist with the diagnosis of psoriasis. Common dermoscopic findings include an erythematous background, regularly distributed vessels, white scale, irregular distribution, and pigmentary changes. In individuals with Fitzpatrick type V-VI skin, differentiating psoriasis from lichen planus, cutaneous lupus erythematosus, and sarcoidosis may be challenging, and skin biopsy may be required for diagnostic confirmation. Sharply demarcated scaly plaques and nail findings such as pitting and onycholysis may further support the diagnosis of psoriasis. Nail psoriasis can be difficult to visualize in darker skin types, since longitudinal melanonychia and darker nail beds can obscure classic features. Limited representation of nail psoriasis in diverse skin types contributes to delayed diagnosis. 

Treatment considerations for psoriasis should incorporate both disease severity and patient hair care practices, particularly when the scalp is involved. For patients who wash their hair less frequently, scalp psoriasis can be managed with weekly use of medicated shampoos in combination with daily topical corticosteroids in an oil-based or lotion formulation. Clinicians should also inquire about traditional or herbal remedies, as these interact with prescribed therapies.  

Body psoriasis is commonly treated with corticosteroids, immunosuppressants and targeted biologic therapies. Despite comparable disease burden, Black patients are significantly less likely to receive biologic therapies and more likely to be managed with topical or non-biologic systemic agents. This highlights the persistent inequities in psoriasis care. Phototherapy is an additional effective treatment option; however, patients should be counseled regarding the potential for exacerbation of post-inflammatory hyperpigmentation. 

Following resolution of active plaques, patients with darker Fitzpatrick skin types frequently have residual hyperpigmented or hypopigmented patches, which may persist for up to 12 months. Patient education regarding the expected course of pigmentary change is essential to set appropriate expectations and support adherence to treatment.