Oral cavity, ligneous gingivitis

The gingival biopsy shows subepithelial accumulation of amorphous eosinophilic material that is PAS positive-diastase resistant and stains purple-red on picro-Mallory stain, confirming the material is fibrin in nature. Ulceration and secondary bacterial colonization are also present. The morphology is consistent with ligneous gingivitis, a condition associated with ligneous conjunctivitis, which is seen in patients with hypoplasminogenemia. The condition is triggered by local injury, trauma or infection and involves mucosal sites. It can be sporadic or familial with autosomal recessive transmission.