|Massive fibrin deposition in a case of recurrent ligneous conjunctivitis in an adult|
I recently signed out a case of ligneous conjunctivitis, a rare form of chronic pseudomembranous conjunctivitis that is marked by a massive accumulation of ﬁbrin. The term ligneous (from the Latin term for "woody") refers to the ﬁrm consistency of the large masses of ﬁbrin that comprise the pseudomembranes. Ligneous conjunctivitis typically occurs in children but may recur in adults. Treatment is often challenging because the inﬂammation is persistent and the pseudomembranes often recur rapidly after excision. Histopathology shows two components: granulation tissue and sheets of intensely eosinophilic acellular amorphous material, which has been shown to be composed predominantly of ﬁbrin. The mass of ﬁbrin also incorporates other serum components such as immunoglobulin. Lesions that resemble those found in the conjunctiva can affect other mucous membranes including the larynx, vagina, and ear. Ligneous conjunctivitis is an autosomal recessive trait caused by mutations in the gene for plasminogen on chromosome 6q26.
Reference: Eagle, Ralph C. Eye Pathology: An Atlas and Text [2nd edition] page 55.