Abnormal Extracellular Material In The Levator Palpebrae Superioris In Congenital Ptosis

Objective: To study the pathologic abnormalities of the levator palpebrae superioris in congenital ptosis. Methods: 43 eyes of 30 cases with congenital ptosis were divided into three groups, muscle expansion of group I was 4~8mm, group II was 2~3mm, group III was 0~1mm. By means of light and electron microscopy and immunohistochemistry, anterior levator tissue specimen escised during routine levator resections were examined. Integration opticdensity (IOD) of collagen type III and fibeonectin in congenital ptosis's levator muscles were measured with computerized image analysis.Results All specimens showed lack of muscle fibers whicharranged irregularly , there were a large of adipose in themuscles. In addition, in the 30 cases, an abnormal extracellularmaterial was present. By light microscopy this appeared as anunusual amorphous material arranged in clumps and bands , andelectron microscopy showed it to consist of parallell coarsebundles of fibrillogranular material. Collagen type III andfibronectin were identified within this material byimmunohistochemistry.There was no detectable collagen typesI,II,IV,V,VI and VI, and the material did not stain for actin,myosin, myoglobin , amyloid P component, or amyloid A. Theexpression of Collagen type III and fibronectin in the differentgroups was significant (p<0.05).Conclusion In 43 samples of levator palpebrae superioris from patients with congenital ptosis, we identified an unusualamorphous extracellular material that stained positively for collagenIII type and fibronectin on immunohistochemistry ,this novel material, which we call "amorphocollagenoid "may represent a product of dysgenesis of the levator tissues . The source and full composition of this material merit further study.