Plasminogen deficiency is a rare congenital condition that leads to pseudomembraneous lesions, such as ligneous conjunctivitis and ligneous gingivitis. Because of its rarity, ligneous gingivitis is not a pathology one may easily suspect from its clinical symptoms. We report the case of a 35-year-old Caucasian woman who experienced gum masses with white spots, but no pain. Based on the clinical picture, one could refute a diagnosis of necrotizing ulcerative periodontitis. Several biopsies were taken. The last ones showed an amorphous eosinophilic substance that could be fibrin. Plasmatic dosage of plasminogen (activity level 44%) confirmed the hypothesis of ligneous gingivitis. This report appears to be a very rare diagnosis of a ligneous gingivitis without major conjunctivitis, associated with a moderate plasminogen deficiency.