Solitary (primary) uveal T-cell lymphoma in a horse

A rare case of ocular and testicular T-cell lymphoma in a hermaphrodite koi carp (Cyprinus carpio Linnaeus 1758): clinical, histopathological, and immunohistochemical study

BACKGROUND

Lymphatic neoplasia may occur in various types, such as lymphoma, lymphosarcoma, lympholeukemia, and plasmacytoid leukemia. Lymphoma, defined as a malignant tumour of lymphoid tissue, has been found in a number of fish families including Esocidae and Salmonidae. However, the occurrence of lymphoma is rare in those belonging to the Cyprinidae. A final diagnosis of ocular and testicular T-cell lymphoma in the present study was based on the clinical signs, morphology, and texture of the tumour masses in the macroscopic and microscopic examinations. In addition, histopathological and immunohistochemical findings corresponded to T-cell lymphoma characteristics.

CASE PRESENTATION

A 2-year-old hermaphrodite koi carp (Cyprinus carpio Linnaeus 1758) with a large ocular mass and severe exophthalmia in the right eye was referred to the Ornamental Fish Clinic in October 2020. Under anesthesia, enucleation was performed. 57 days after enucleation of the right eye, exophthalmia in the left eye was discovered. 221 days after surgery, the fish was discovered to be dead. At necropsy, a large soft tissue mass attached to the left testis was discovered. There were also small whitish nodules on the surface of the liver. Histopathology revealed a hypercellular ocular mass with scant connective tissue. The sections also revealed multifocal hemorrhages, round to ovoid neoplastic cells, mild-to-moderate anisokaryosis and anisocytosis, and mitotic figures. Basophilic neoplastic cells were found in blood vessels within the testicular mass, raising the possibility of systemic spread. The liver showed microscopic metastasis with morphologic similarities to the ocular and testicular tumors. The neoplastic cells infiltrating the left and right eyes as well as the testicular mass were immunohistochemically positive for CD3 but negative for CD20. The masses were diagnosed as T-cell lymphoma based on histopathological and immunohistochemical findings.

CONCLUSIONS

This case report provides the first evidence of clinical, histopathological, morphological, and immunohistochemical findings of an ocular and testicular T-cell lymphoma in a hermaphrodite koi carp (Cyprinus carpio) in Iran.

Infectious Uveitis in Horses and New Insights in Its Leptospiral Biofilm-Related Pathogenesis

Uveitis is a sight-threatening eye disease in equids known worldwide that leads to considerable pain and suffering. By far the most common type of uveitis in Germany and neighboring countries is classical equine recurrent uveitis (ERU), which is caused by chronic intraocular leptospiral infection and is the main cause of infectious uveitis in horses. Other infectious causes are extremely rare and are usually clinically distinguishable from ERU. ERU can be treated very effectively by vitreous cavity lavage (vitrectomy). For proper indications of this demanding surgery, it is necessary to differentiate ERU from other types of uveitis in which vitrectomy is not helpful. This can be conducted on the basis of anamnesis in combination with ophthalmologic findings and by aqueous humor examination. During vitrectomy, vitreous material is obtained. These vitreous samples have historically been used for numerous etiologic studies. In this way, a chronic intraocular leptospiral infection has been shown to be the cause of typical ERU and, among other findings, ERU has also been recognized as a biofilm infection, providing new insights into the pathogenesis of ERU and explaining some thus far unexplainable phenomena of ERU. ERU may not only have transmissible aspects to some types of uveitis in humans but may also serve as a model for a spontaneously occurring biofilm infection. Vitreous material obtained during therapeutically indicated vitrectomy can be used for further studies on in vivo biofilm formation, biofilm composition and possible therapeutic approaches.

Uveal myxoid leiomyosarcoma in a horse

A uveal leiomyosarcoma of a horse is reported. There are few published reports of intraocular tumors in horses. Intraocular tumors challenge animal welfare by causing uveitis, glaucoma, and loss of vision. Knowledge regarding treatment of intraocular tumors with globe preservation is sparse, and further investigations on this topic are required.

Enucleation in equids with and without the use of an orbital suture meshwork implant: a retrospective study of 37 cases

This retrospective study on 37 horses was conducted to assess long-term complications, scarring, cosmetic appearance and owner satisfaction of horses that underwent transpalpebral enucleation with (n=26) or without (n=11) non-absorbable sutured meshwork prosthesis between 2006 and 2013. Postoperative complications related to the surgery were wound infection, discharge and dehiscence, and no significant difference between groups was found. In one horse, the meshwork had to be removed in order to treat a chronic fistula. Horses with infection or inflammation before surgery were more likely to encounter postoperative complications, whether or not a meshwork was used. Most owners were satisfied by the surgical technique for scarring, but contrary to the present hypothesis, most horses with a meshwork implant had a poor sunken-in appearance, and 26 per cent of owners would like to attempt other techniques to improve the cosmetic result. Also, a further 44 per cent of owners would prefer a better cosmetic result if the technique does not increase complication risk or cost. Meshwork implant prosthesis after transpalpebral enucleation was safe. However, in order to achieve a better cosmetic result, further improvements of the technique will be required.