Diagnosis: Isolated oropharyngeal pemphigus vulgaris.
The differential diagnosis for painful oral ulcerative lesions is broad and includes squamous cell carcinoma (SCC), aphthous ulcers, herpes simplex, traumatic ulcers, Behçet disease, and the pemphigus group of diseases. Oral SCC may present as an ulcerative lesion that is painful or painless, typically has a slowly progressive course, and is very firm to palpation; often patients have considerable tobacco and/or alcohol exposure (as in this patient). Diagnosis is by biopsy, demonstrating atypical squamous cells with intercellular bridges and keratin production, either keratin pearls or cytokeratin expression, on immunohistochemical analysis. Apthous ulcers are quite common and present as recurring, well-circumscribed ulcers confined to the oral cavity and often beginning in childhood, as opposed to the diffuse ulcer observed in this patient, who had no childhood history of aphthous ulcers. Histologic characteristics of aphthous ulcers are nonspecific but will typically demonstrate granulation tissue and a fibrinous exudate in the ulcer bed. Traumatic ulcers are similarly nonspecific, but patients will often report a history of trauma to the tongue or buccal mucosa. Behçet disease is a multisystem disease of unknown etiology that may present with aphthous ulcers but also involves the eyes and skin. Herpes simplex will present with recurrent distinct blistering lesions that may ulcerate rather than the diffuse ulcer observed in this case. Histologic findings will show typical nuclear viral inclusions defined by margination of the chromatin and small pink deposits with a clear halo, known as Cowdry A inclusions.