Faecal Occult Blood Test

Case of the Month (Emma Scurrell April 2012)

Corneal inclusion cysts in a dog

The following are H&E sections prepared from a keratectomy specimen in a 4-year-old male neutered pug. The pug had a history of a deep corneal ulcer in the right eye which was surgically repaired using a conjunctival pedicle graft. Six months later, the superficial cornea had developed two discrete, smooth, creamy yellow-white nodular lesions (up to 2.0 x 1.5 x 3.0mm in diameter) at the site of the conjunctival graft. These lesions were clinically consistent with corneal inclusion cysts and a keratectomy was performed to excise them. 

 Fig 1. This is a low power view of the first nodule in which a discrete epithelial-lined cyst is evident in the corneal stroma. Note how the epithelium lining of the cyst is contiguous with the downgrowth of corneal epithelium (black arrows). 

Fig 2.  Low power view of the second discrete cyst within the corneal stroma.

Fig 3.  The cysts are lined by well-differentiated benign stratified squamous epithelium and the lumen of the cysts typically contain abundant neutrophils and desquamated epithelial cells (black circle) which gives the cysts their creamy yellow appearance.   

Final Diagnosis

Multiple corneal inclusion cysts


Corneal inclusion cysts are uncommon, benign lesions in domestic animals. They may be congenital however the vast majority are acquired and are usually associated with previous trauma, including surgical trauma (e.g. at the site of sutures). The most likely pathogenesis is a downgrowth or embedding of corneal epithelium within the corneal stroma with associated epithelial proliferation and cyst formation. The cysts typically contain abundant neutrophils and squames which is what will be seen cytologically if these lesions are aspirated. Many of the cysts tend to be relatively superficial in the corneal stroma and can be excised by keratectomy. 

Previous Monthly Cases

Hypertensive Retinopathy January 2010
FIP in a cat - uncommon presentation February 2010
Phaeohyphomycosis    March 2010 
Scleral Rupture April 2010
Canine and feline epulides May 2010
Erythema multiforme in a labrador retreiver June 2010
Keloidal fibrosarcoma in a labrador retreiver July 2010
Cutaneous epitheliotropic lymphoma  August 2010 
Benign cutaneous histiocytoma  September 2010 
Iridociliary adenoma October 2010
Proliferative thrombovascular necrosis of the pinnae November 2010
Signet-ring cell carcinoma in the stomach of a dog December 2010
Cutaneous infiltrative lipoma in a labrador January 2011

Tonsillar squamous cell carcinoma February 2011
Canine orbital meningioma March 2011
"Lung-digit" syndrome in a cat April 2011
Hepatic amyloidosis in a cat May 2011
Haemophagocytic histiocytic sarcoma June 2011
Alternaria spp. infection in an immunocompromised dog July 2011
Ocular manifestation of lymphoma in a cat  August 2011
Kerion dermatophytosis in a Cocker spaniel September 2011
Subcuticular coenurus in a rabbit  October 2011
Optic nerve glioma in a dog November 2011
Malignant transformation of a viral papilloma in a dog  December 2011
Uveodermatological syndrome in an Akita
January 2012
Cutaneous angiostomatosis in a dog  February 2012
Transitional cell carcinoma in a dog  March 2012

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Faecal Occult Blood Test