Psoriasiform mucositis on the gingival and palatal mucosae treated with retinoic-acid mouthwash

A 35-year-old African-American female sought our clinic for evaluation of a burning sensation on the palate and gingival bleeding of one-year duration. Oral examination showed diffuse erythema on the upper gingival mucosa, resembling a desquamative gingivitis (Fig. 1a), and erythematous patches on the hard and soft palatal mucosa (Fig. 1b,c). No other lesion was reported either on the skin or on other mucosal surfaces. The patient was neither a smoker nor an alcohol abuser; otherwise she was in good health. Her family history presented nothing noteworthy.

Figure 1.  Left column: characteristics of lesions at initial consultation: (a) diffuse erythema with some small white patches on the gingival mucosa, resembling a desquamative gingivitis; (b) and (c) erythematous patches with tiny white granulation on the hard and soft palate. Right column: 8 months after treatment: (d) nearly complete resolution of gingival lesion; (e) and (f) substantial improvement on palatal lesions with a persistent erythematous patch on the palatal rugae

The diagnostic procedure began with microscopic examination of biopsies taken from the palatal and gingival mucosae, which were consistent with psoriasiform lesion (Fig. 2a–d). Periodic acid-Schiff staining of the histopathological slide sections was negative for Candida infection. A serological test for syphilis was non-reagent, and a complete blood cell count was within normal limits.

Figure 2.  Microscopic aspects of biopsied lesions showing psoriasiform mucositis. (a) Hard palate mucosa lined by squamous epithelium with acanthosis and discrete hyperkeratosis. Exocytosis is seen throughout the epithelium. The lamina propria connective tissue showed moderate leukocyte infiltration and congested blood vessel in the papillar area (H&E, × 100).(b) High-power magnification of the same section evidencing the intraepithelial microabscesses, known as Munro abscesses(H&E, × 400). (c) Gingival specimen presenting mostly the same aspects as observed in the hard-palate section, but withless prominent inflammatory infiltrate (H&E, × 100). (d) Intraepithelial abscesses are, nevertheless, present (H&E, × 400).No fungus was seen with periodic acid-Schiff staining in either section

This histopathological pattern in oral soft tissues calls for a differential diagnosis that usually includes candidosis, secondary syphilis, Reiter’s syndrome, erythema migrans, and oral psoriasis.^1,2 Candida and syphilis infection were excluded by negative exam results; Reiter’s syndrome was excluded due to the lack of associated symptoms (i.e. conjunctivitis, urethritis, and arthritis); erythema migrans (also known as geographic stomatitis or ectopic geographic tongue) was ruled out because the lesions did not show the clinical features characteristic of this condition (i.e. a circinate morphology and a pattern of migration in location and size); while oral psoriasis was also excluded as the patient did not exhibit the clinical diagnostic criteria, namely the presence of skin psoriasis lesions (examination by a dermatologist found no cutaneous/or nail lesions, or genital involvement), a positive family history, and human leukocyte antigen (HLA) typing (HLA typing was not available). Consequently, the final clinical diagnosis was oral psoriasiform mucositis.

Management began with a periodontal treatment (dental scaling for reducing gingival inflammation), followed by a 0.02% retinoic-acid mouthwash (simply retinoic acid and purified water) used twice daily. After eight weeks of treatment, a substantial improvement was observed (Fig. 1d,f), along with disappearance of the oral symptom. The medication was discontinued, and throughout eight months of follow-up, an erythematous patch on the hard palate persisted (Fig. 1e).

True oral psoriasis lesions have been scarcely reported.^1–3 The rare cases on the oral mucosa that show histopathological features characteristic of psoriasis seldom fulfill the clinical criteria for a diagnosis of oral psoriasis.^1–4 The present case showed a histopathological appearance consistent with psoriasiform lesions, leading to initial speculations that it could be a manifestation of psoriasis affecting exclusively the oral mucosa. Such a diagnosis, however, would only be valid if based on a positive family history of the disease and presence of HLA typing for either B13, B17, Cw4, or Cw6, these being the HLA antigens most frequently associated with psoriasis.^1,2,5 As these important criteria were lacking in the present case, a cautious judgment was preferable, considering it as oral psoriasiform mucositis, rather than as a case of isolated oral psoriasis.

This diagnosis of oral psoriasiform mucositis demands that the clinician should first rule out some other oral inflammatory entities that share a histopathological similarity with that of psoriasis and, secondly, make an attempt at treating it when necessary.

For the present case, a topical retinoic was chosen, as it displays anti-psoriatic properties, mainly to maintain normal epithelial homeostasis.^2,6 A mouthwash formulation was preferable, as the lesions were scattered on the palatal and gingival mucosae. The mouthwash was used at a low concentration (0.02%) to avoid mucosal irritation.

This therapeutic measure proved effective, and it may be an option for treating these lesions.