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plasminogen deficiency type I
The most common clinical feature of this disorder is conjunctivitis often precipitated by an injury or infection of the conjunctiva with typical inflammatory features. A thick, ligneous (wood-like) pseudomembrane containing clotted fibrin subsequently forms that appears white, yellow-white, or finally red. These can be surgically removed but tend to recur, often on an accelerated timescale. This process is most pronounced on the upper tarsal conjunctiva but often involves the bulbar conjunctiva and the cornea as well. Corneal involvement (in nearly a third of cases) can lead to vascularization, scarring, keratomalacia, and perforation. The disease may be intermittent.
While the conjunctiva is most commonly involved, other mucosal surfaces such as oral, laryngeal, tracheal, and vaginal mucosas may have similar disease often concomitantly with the ocular lesions. Ligneous gingivitis consists of nodular lesions with ulceration and peridodontal tissue destruction. The ear may also be involved in the disease. Life-threatening airway obstruction is a threat, especially in children during acute recurrences. Occlusive hydrocephalus requiring shunting occurs in a significant number of affected children.
This condition seems to result from homozygous mutations in the PLG gene (6q26) that codes for plasminogen and therefore is inherited in an autosomal recessive pattern. Tears contain plasminogen activators that convert plasminogen into the fibrinolytic enzyme plasmin which normally clears conjunctival and corneal fibrin deposits. The lack of normal plasminogen allows fibrin to accumulate on all mucosal surfaces.
A variety of topical treatments have been tried with plasminogen being the most promising. This treatment if given systemically may also be beneficial in disseminated disease. Surgical excision of the pseudomembrane is possible but multiple recurrences are common. Spontaneous resolution has been reported.