Eye, Cornea - Mineralization

Image of cornea mineralization in the eye from a female F344/N rat in a chronic study
Eye, Cornea - Mineralization in a female F344/N rat from a chronic study. There are basophilic linear deposits within and subjacent to the corneal epithelial basement membrane (arrow).
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Image of cornea mineralization in the eye from a female B6C3F1 mouse in a chronic study
Eye, Cornea - Mineralization in a female B6C3F1 mouse from a chronic study. There are irregular basophilic deposits (arrow) in the stroma with concurrent stromal granulomatous inflammation (arrowhead).
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Image of cornea mineralization in the eye from a male F344/N rat in a chronic study
Eye, Cornea - Mineralization in a male F344/N rat from a subchronic study. There are pale to dark basophilic foci of mineralization (arrows) at the corneal limbus in the eye and concurrent corneal epithelial hyperplasia (arrowhead).
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comment:

Corneal mineralization in rats and mice can be a sequela to trauma or inflammation, can result from exposure to topical irritants or systemic toxins, or can occur as a spontaneous change. One form of mineralization that occurs spontaneously in rats and mice is known clinically as corneal dystrophy, band keratopathy, or calcific keratopathy. Clinically, white, punctuate to linear corneal opacities are first noted in the central (axial) cornea in the zone corresponding to the interpalpebral fissure. Microscopically, linear to irregular aggregates of mineralization are present within or just under the central corneal epithelial basement membrane ( Figure 1image opens in a pop-up window ). There is diffuse thinning of the overlying corneal epithelium and swelling of the corneal epithelial basal cells. Mineralization can also occur deeper in the corneal stroma ( Figure 2image opens in a pop-up window ). Mineralization may also occur at the corneal limbus ( Figure 3image opens in a pop-up window ). Mineralization may be accompanied by corneal epithelial hyperplasia or secondary granulomatous inflammation.

recommendation:

When mineralization is considered a primary change, it should be diagnosed and assigned a severity grade. The location of the mineral deposits (e.g., subepithelial) should be described in the pathology narrative. When mineralization is secondary to inflammation, it should not be diagnosed separately, unless warranted by severity, though it should be described in the narrative.

references:

Bruner H, Keller WF, Stitzel KA, Sauers LJ, Reer PJ, Long PH, Bruce RD, Alden CL. 1992. Spontaneous corneal dystrophy and generalized basement membrane changes in Fischer-344 rats. Toxicol Pathol 20:357366.
Abstract: http://www.ncbi.nlm.nih.gov/pubmed/1295066

Frame SR, Slone TW. 1966. Nonneoplastic and neoplastic changes in the eye. In: Pathobiology of the Aging Mouse, Vol 2 (Mohr U, Dungworth DL, Capen CC, Carlton WW, Sundberg JP, Ward JM, eds). ILSI Press, Washington, DC, 97-103.

Geiss V, Yoshitomi K. 1991. Eyes. In: Pathology of the Mouse: Reference and Atlas (Maronpot RR, Boorman GA, Gaul BW, eds). Cache River Press, Vienna, IL, 471-489.
Abstract: http://www.cacheriverpress.com/books/pathmouse.htm

Greaves P. 2007. Nervous system and special sense organs. In: Histopathology of Preclinical Toxicity Studies: Interpretation and Relevance in Drug Safety Evaluation, 3rd ed. Academic Press, San Diego, CA, 861-933.
Abstract: http://www.sciencedirect.com/science/book/9780444527714

Guillet R, Wyatt J, Baggs RB, Kellogg CK. 1988. Anesthetic-induced corneal lesions in developmentally sensitive rats. Invest Ophthalmol Vis Sci 29:949-954.
Full Text: http://www.iovs.org/content/29/6/949.full.pdf

Kuno H, Usui T, Eydelloth RS, Wolf ED. 1991. Spontaneous ophthalmic lesions in young Sprague-Dawley rats. J Vet Med Sci 53:607-614.
Abstract: http://www.ncbi.nlm.nih.gov/pubmed/10845604

Losco PE, Troup CM. 1988. Corneal dystrophy in Fischer 344 rats. Lab Anim Sci 38:702-710.
Abstract: http://www.ncbi.nlm.nih.gov/pubmed/3265461

Meador VP, Tyler RD, Plunkett ML. 1992. Epicardial and corneal mineralization in clinically normal severe combined immunodeficiency (SCID) mice. Vet Pathol 29:247-249.
Abstract: http://vet.sagepub.com/content/29/3/247.short

National Toxicology Program. 2004. NTP TR-515. Toxicology and Carcinogenesis Studies of Propylene Glycol Mono-t-butyl Ether (CAS No. 57018-52-7) in F344/N Rats and B6C3F1 Mice and a Toxicology Study of Propylene Glycol Mono-t-butyl Ether In Male NBR Rats (Inhalation Studies). NTP, Research Triangle Park, NC.
Abstract: http://ntp.niehs.nih.gov/go/7724

Smith RS, Sundberg JP, John SWM. 2002. The anterior segment. In: Systematic Evaluation of the Mouse Eye: Anatomy, Pathology, and Biomethods (Smith RS, John SWM, Nishina PM, Sundberg JP, eds). CRC Press, Boca Raton, FL, 111-159.

Taradach C, Greaves P, Rubin LF. 1984. Spontaneous eye lesions in laboratory animals: Incidence in relation to age. Crit Rev Toxicol 12:121-147.
Abstract: http://www.ncbi.nlm.nih.gov/pubmed/6368130

Van Winkle TJ. 1991. Corneal opacities, spontaneous, mouse. In: International Life Sciences Institute Monographs on the Pathology of Laboratory Animals, Vol 10, Eye and Ear (Jones TC, Mohr U, Hunt RD, eds). Springer, Berlin, 21-25.

Williams DL. 2005. Ocular disease in rats: A review. Vet Ophthalmol 5:183-191.
Abstract: http://www.ncbi.nlm.nih.gov/pubmed/12236869

Yamate J, Tajima M, Maruyama Y, Kudow S. 1987. Observations on soft tissue calcification in DBA/2NCrj mice in comparison with CRJ:CD-1 mice. Lab Anim 21:289-298.
Abstract: http://www.ncbi.nlm.nih.gov/pubmed/3695386

Yoshitomi K, Boorman GA. 1990. Eye and associated glands. In: Pathology of the Fischer Rat: Reference and Atlas (Boorman GA, Eustis SL, Elwell MR, Montgomery CA, MacKenzie WF, eds). Academic Press, San Diego, CA, 239-260.
Abstract: http://www.ncbi.nlm.nih.gov/nlmcatalog/9002563