Canine Eyelid Tumors

Granular cell tumors (GCTs) are rare, solitary, slowly growing benign tumors found in older dogs and have reportedly appeared on the tongue, ear, lip, palate, meninges, cerebral cortex, heart, lymph node, and skin. Clinical and pathologic features were analyzed in GCTs from the medial canthal eyelid of 8 dogs, ranging in age from 5–12 years (mean, 9.2 years). Presentations included swollen hyperemic eyelids (4/8 dogs), ulcerated skin overlying the mass (2/8), and red conjunctiva (7/8). All had firm masses extending from the palpebral conjunctiva to the eyelid margin at the medial canthus. Seven cases had follow-up data available; recurrence after mass excision was not seen.

Tumor histology demonstrates a highly collagenous matrix. Cells contain granular cytoplasm because of a lysosome accumulation and was positive on periodic Acid-Schiff stain because of lysosome prevalence. Distinctive cytopathologic features allow for diagnosis on fine-needle aspirate cytology, but histopathology is the diagnostic standard. In dogs, GCTs should be a differential for tumors of the medial canthus. With proper excision, prognosis is excellent; recurrences have not been seen in humans or dogs.

CommentaryA consistent feature of the canine eyelid tumor is its medial canthal location. Although excision of this benign mass is reportedly curative, the tumor’s proximity to the nasolacrimal puncta and canaliculi must be considered when formulating a surgical plan. The novice surgeon should consider referral to optimize preservation of the tear drainage system.

The eosinophilic granularity of the tumor cells’ cytoplasm is attributed to an accumulation of lysosomes. This feature is sufficiently distinctive for a cytologic diagnosis of a fine-needle aspirate and is distinguishable from metachromatic cytoplasmic granules (eg, those found in mast cell tumors).—Mary B. Glaze, DVM, MS, DACVO

SourceCanine eyelid granular cell tumor: A report of 8 cases. Lu JE, Dubielzig R. VET OPHTHALMOL 15:406-410, 2012.