Immunohistochemical Analysis of the Lacrimal Sac Mucopeptide Concretions.

Purpose: To investigate the presence and distribution patterns of proteins in the lacrimal sac mucopeptide concretions.

Methods: The study was performed on 10 mucopeptide concretions obtained from the lacrimal sac during an endoscopic dacryocystorhinostomy. Immunohistochemical labeling was performed for assessing the presence and distribution of von Willebrand factor, fibronectin, collagen I, collagen III, human beta-defensin 2, beta-defensin 3, lysozyme, prolactin, cytokeratin (CK)-CK4, CK7, CK18, immunoglobulin M (IgM), immunoglobulin G (IgG), psoriasin (S100-A7), and migration inhibitory factor-related protein (MRP14/S100-A9). The results were then scored as positive or negative and the distribution pattern, if any, within the sectioned concretions was assessed.

Results: Immunohistochemical labeling was strongly positive for von Willebrand factor and fibronectin in the core areas of the concretions. Collagen I was widely dispersed both in the peripheral and core areas whereas collagen III was mostly limited to only few areas of the core. Strong immunoreactivity was noted for lysozyme, which was abundantly distributed, whereas prolactin receptors were positive on the surface and also the dispersed cells within the concretion matrices. Very few peripheral areas of concretions showed MRP14 or S100-A9 positivity in a noncontiguous fashion. Immunoreactivity was uniformly negative for CK-18, IgM, IgG, and psoriasin.

Conclusions: The presence of fibronectin and von Willebrand factor in the core of the concretions strengthens the earlier hypothesis that blood components may act as a nidus for subsequent mucopeptide deposition. The study also provides possible clues to the lacrimal defenses mounted during dacryolithiasis.Fibronectin and vWF are present in the core of the dacryoliths. Blood components may act as a nidus in the evolution of lacrimal sac mucopeptide concretions.