Primary bilateral corneal T cell lymphoma in a horse

Abstract

A 5-year-old Belgian Warmblood gelding presented for evaluation of increased opacity in both eyes. Initial ophthalmic examination revealed bilateral mild blepharospasm, multifocal axial and dorsal anterior stromal corneal opacities with mild axial mid-stromal haze and oedema, and superficial, branching corneal vascularisation. A presumptive diagnosis of bilateral immune-mediated keratitis (IMMK) was made. The lesions progressed despite 2 years of exhaustive options for medical management. Surgical intervention in the left eye with lamellar keratectomy and ocular surface reconstruction with amnion membrane transplantation was elected. The keratectomy specimen was submitted for histopathology and was consistent with immune-mediated keratitis. When surgical intervention in the right eye was performed, histopathology revealed sheets of atypical round cells with a high mitotic index. Immunohistochemistry from both the left and right specimens had immunoreactivity to CD3 antibodies. An amended diagnosis of bilateral T cell lymphoma was made. The patient recovered well from surgery, and there have been no signs of recurrence or systemic involvement following surgical intervention. This is a unique case of primary corneal T cell lymphoma in a horse. Prior to electing surgical management, the patient received topical immunomodulating medications including cyclosporine and tacrolimus for significant lengths of time. Both chronic inflammation and chronic administration of immunosuppressive agents are associated with neoplastic transformation. Surgical intervention provides both a diagnostic sample and therapeutic relief.

The long‐term outcomes of standing superficial keratectomy as the sole treatment of corneal B‐cell lymphoma in five horses in the UK: Clinical, histopathology, immunohistochemical and molecular findings

“…All patients in this case series received topical ciclosporin for the treatment of presumed IMMK at some point during the course of disease. Ciclosporin is a calcineurin inhibitor, which inhibits T‐cell action by inhibiting the transcription of genes involved in cytokine production by activated T‐lymphocytes, including interleukin‐2 (IL‐2) (Opgenorth et al., 2021). IMMK is an established immunologic disorder of the equine cornea, presumed to be a dysregulation of the adaptive immune responses but the exact aetiogenesis remains unknown (Matthews, 2000).…”

“…Solitary extraocular lesions of lymphoma have been reported involving the eyelid, conjunctiva, third eyelid and corneoscleral limbus (Rebhun & Del Piero, 1997; Schnoke et al., 2013). Reported cases of solitary ocular lymphoma include a horse with uveal T‐cell lymphoma (Trope et al., 2014), a horse with bilateral corneal T‐cell lymphoma and one horse with corneal B‐cell lymphoma (Opgenorth et al., 2021; Vallone et al., 2016). In both reported cases of corneal lymphoma, a superficial keratectomy was performed under general anaesthesia and both had adjunctive therapies.…”

“…In the case of B‐cell corneal lymphoma, a superficial keratectomy was accompanied by brachytherapy and chemotherapy (Vallone et al., 2016). The horse with bilateral corneal T‐cell lymphoma was treated by superficial keratectomy with the addition of amnion membrane transplant and subconjunctival ciclosporin (Opgenorth et al., 2021). A recent publication reported a case of corneal B‐cell lymphoma in the USA treated with a superficial keratectomy performed standing (Lisankis et al., 2022).…”

Corneal neoplasia in horses

“…Primary corneal neoplasia is rarely encountered in equine practice. In the current issue of Equine Veterinary Education , Opgenorth and colleagues (2022) report a case of primary corneal lymphoma. Multiple cases of multicentric lymphoma affecting the eye have been described in horses (Martabano et al., 2019), but primary ocular lymphoma is rare.…”