Ligneous conjunctivitis (LC) is a rare form of chronic conjunctivitis characterised by the recurrent formation of pseudomembranous lesions most commonly on the palpebral surfaces. It is most frequently reported as a clinical manifestation of severe homozygous or compound-heterozygous hypoplasminogenemia (see this term).
Prevalence in the general population is unknown but estimates range between 0.13% and 0.42% in healthy subjects with heteterozygous hypoplasminogenemia. More than 200 cases have been reported so far. Most cases involve infants and children.
The condition is characterized by initial chronic tearing and redness of the conjunctivae with the subsequent formation of fibrin-rich pseudomembranes. These pseudomembranes form mostly on the upper tarsal conjunctiva but involvement of the lower eyelid and bulbar conjunctiva have been reported. The lesions progress to form white, yellow-white, or red thick masses with a wood-like consistency that replace normal mucosa. The disease is bilateral in around half of cases and corneal involvement is present in around a third of cases. LC appears to be the ocular manifestation of a systemic disease and is often associated with lesions on the mucosa of the mouth, nasopharynx, tracheobronchial tree, intestines, kidneys, female genital tract and ear. Occlusive hydrocephalus and juvenile colloid milium have been reported in some cases.
In predisposed subjects (individuals with hypoplasminogenemia), LC may be triggered by local injuries, local and systemic infections, and various types of eye surgery. LC (and its associated complications) is caused by homozygous or compound-heterozygous hypoplasminogenemia (type I plasminogen deficiency), which results from mutations in the plasminogen gene (PLG; 6q26). In addition, transitory LC has been induced in a female patient as a side effect of tranexamic acid treatment.
The differential diagnosis should include other forms of chronic conjunctivitis.
Prenatal diagnosis has been reported in a family in which the PLG gene mutation had been identified.
Although most cases are sporadic, familial cases with autosomal recessive transmission have been reported.
The ocular lesions may be managed by topical treatments: in August 2007, human plasminogen (in the form of eye drops) was granted EC orphan drug designation for the treatment of LC (however, this treatment is not yet commercially available). Other treatment approaches include: topical and subconjunctival fresh frozen plasma (FFP), administration of standard heparin in combination with topical corticosteroids or alpha-chymotrypsin, and topical (or systemic) application of immunosuppressive drugs (cyclosporine A, azathioprine). Surgical excision of pseudomembranes and other mechanical manipulations involving the eye should be avoided.
The visual prognosis is moderate. Corneal involvement may lead to blindness due to scarring, vascularisation, keratomalacia and perforation.
Last update: April 2008