RESUMEN
OBJECTIVES: Oral premalignant and malignant lesions may mimic oral lichen planus (OLP) clinically and microscopically. OLP often shows basement membrane fibrinogen positivity on direct immunofluorescence testing (DIF). This study examined fibrinogen positivity in oral premalignant lesions and squamous cell carcinoma. STUDY DESIGN: The University of Florida Oral Pathology Biopsy Service records were searched for the years 2003 to 2013 for oral premalignant lesions and squamous cell carcinoma with concurrent DIF testing. Demographic, clinical, and DIF or histologic information was collected and analyzed. RESULTS: Sixty-eight fibrinogen positive lesions were identified within a total of 164 cases. Low-grade dysplasia and premalignant verrucous lesions made up the majority of the fibrinogen positive lesions (combined n = 43; 63.2%), and the most common locations in positive cases were the buccal mucosa, tongue, and gingiva. A lichenoid distribution of the inflammatory infiltrate significantly predicted fibrinogen positivity (P < .0005). CONCLUSIONS: Fibrinogen positivity may be seen in premalignant and malignant oral lesions increasing the risk of misdiagnosis.