Oral Lichenoid Reactions:
Oral lichenoid reactions (OLRs) or oral lichenoid lesions (OLLs) are
clinically and histologically similar to lichen
planus63. Lichen planus is a severe chronic
inflammatory disorder that can affect the skin and lining mucosa,
including oral, oesophageal, and genital mucosa. Oral lichenoid
reactions are reported to affect about 1-2% of the population, with
women more commonly affected than men 10. Oral lichen
planus usually occurs on the buccal mucosa, gingivae, and tongue.
Clinical presentations of oral lichenoid reactions vary from white
striated reticular patterns to white and red confluent plaques,
ulcerations, and erosions. A case was reported with
pembrolizumab-induced oral graft versus host disease (GVHD) or lichen
planus like lesion 144.
Pathogenesis: While the etiology of oral lichenoid reactions is
unknown, but it is supposed to be an immunologically T-lymphocyte
mediated reaction to the keratinocytes present on the basal surface of
the skin or mucosal membrane 63.
Clinical presentation : Eighteen cases of oral lichenoid reactions
were reported with anti-PD-1/PD-L1 immunotherapy. Cases associated with
various drugs are as follows, four with
pembrolizumab145, 146, fourteen with
nivolumab146-150. The time from initiation of
anti-PD-1/PD-L1 treatment to the development of oral lichenoid reactions
ranges from two weeks to four years with the dosing regimen of
pembrolizumab: 200 mg /2mg/kg I.V., every 3 weeks, nivolumab = 200 mg
I.V. every 15 days, 480 mg every 4 weeks, 240 mg I.V. q2w, 3 mg/kg I.V.
q2w. Oral lichenoid reactions occur in patients within the age of 26-93
years (mean=62). The disease arises on the buccal mucosa, soft palate,
ventral and dorsal aspect of the mouth and tongue, labial mucosa,
gingivae, and the hard palate. Clinical and histological findings of the
disease include the occurrence of a white striated reticular pattern to
red confluent plaques erosion, wickham striations ulcerations, or
erosions.
Treatment: Patients responded well to the topical steroid
therapies (prednisone, methylprednisone) 148 when
prescribed for oral irAEs. Other treatments have also been evolved which
include betamethasone cream 147, dexamethasone 0.1
mg/ml solution 149, fluocinonide 0.05% gel, Oracort
dental paste, triamcinolone acetonide 0.1% paste 146.