Oral Psoriasis: Diagnosis and Treatment

Cutaneous psoriasis is frequently encountered in clinical practice, in contrast to oral psoriasis, which is considerably less common.¹ A recent article by Fatahzadeh and Schwartz¹ reviews the diagnosis and management of this rare condition, which the authors describe as an “overlooked enigma.”

Why is Oral Psoriasis So Rarely Diagnosed?

The authors characterize the true incidence of oral involvement in psoriasis as “unknown” because few patients with psoriasis actually have their oral cavities carefully examined.² One reason for this omission is that oral lesions are often asymptomatic, and therefore do not come to the clinician’s attention. The diagnosis, when it is made, is rarely confirmed histologically.³ Moreover, there is a more accelerated rate of epithelial turnover in cutaneous lesions than in oral lesions, so oral changes are “clinically subtle and difficult to recognize.”¹

Perioral and Oral Manifestations of Psoriasis

There are several different locations in the perioral and oral areas that can be affected by psoriasis. Psoriatic involvement of the vermilion border is “rare,” according to the authors, and may occur with or without oral cavity involvement. Since the lips are partially keratinized, psoriasis affecting that region behaves similarly to cutaneous lesions, presenting with diffuse erythema, fissuring, silvery scales, and desquamation that starts from the commissures and spreads to involve both lips. It can be accompanied by bleeding, serious exudate, itching, and discomfort aggravated by mastication and lip movements.⁴ It is often confused with solar cheilosis, chronic eczema, actinic dermatitis, chronic candidiasis, or leukoplakia, leading to delayed diagnosis.⁴

Psoriasis usually affects the oral cavity in the buccal mucosa, with the palate and gingiva less frequently affected.³ Morphological patterns include diffuse, intense mucosal erythema associated with acute psoriatic flares, well-defined, annual, white or grayish-yellow lesions, and mixed, ulcerative vesicular, pustular, and indurated entities.¹ Oral findings can be transient, migratory, and frequently fluctuating parallel to the exacerbation or remission of cutaneous lesions.¹ There is a higher prevalence of benign migratory glossitis (BMG) and fissured tongue (FT) in psoriatic patients, compared to the general population.¹

Evaluating Patients with Suspected Oral Psoriasis

The clinical differential diagnosis is “extensive,” and includes a wide range of inflammatory, ulcerative, blistering, and infectious conditions. (Table 1) Typical symptoms include oral pain, burning, or changes in taste perception. Additional concerns that patients may express include the malignant potential of lesions, or the unsightly appearance of the affected visible mucosa.¹

The histological features may be difficult to differentiate from those of other psoriasiform disorders because they closely resemble cutaneous psoriasis.¹ However, a tissue biopsy for histopathology and immune studies is important to exclude vesiculobullous conditions.¹ It is important to note that certain histological criteria (eg, Munro’s abscesses) “may not be fully applicable to its oral counterpart.”¹