Disseminated lymphoid neoplasia and hepatoblastoma in an Atlantic stingray, Hypanus sabinus (Lesueur 1824)

Spontaneous branchioblastoma in a koi carp

Gill neoplasia in fish is rare but has been reported in multiple elasmobranch and teleost species. Although more commonly a site of metastatic disease, primary neoplasms of the gill may occur, and both spontaneous and chemically induced tumors have been reported. Here we describe a spontaneous branchioblastoma in a koi carp (Cyprinus rubrofuscus) with no known history of chemical exposure. A soft-tissue mass on the inner surface of the dorsal opercular chamber appeared to originate from either a gill arch or a pseudobranch. Histologically, the mass was comprised of 3 well-differentiated cell types: blastemal cells, epithelial cells arranged in a lamellar fashion, and islands of cartilage resembling those present in gill filaments. To our knowledge, this is only the fourth case of spontaneous branchioblastoma recorded in koi.

Use of computed tomography to determine body surface area and K-constant in Atlantic Stingrays for chemotherapeutic dosing

OBJECTIVE

The objective of this study was to use body surface area (BSA) obtained via computed tomography (CT) to calculate a species-specific shape constant (K) and provide a formula for BSA based on body weight (BW) in Atlantic Stingrays Hypanus sabina. Ultimately, this information can be used to more accurately calculate chemotherapeutic doses and other metabolic-related measures.

METHODS

Six deceased Atlantic Stingrays of unknown age and with a range of sizes were collected during a natural mortality event and underwent CT scans. Following the scans, three-dimensional surface models were created from the imaging data to measure BSAs and derive a BSA formula based on BW. Nonlinear regression analysis of BSA versus thawed BW was performed, and a species-specific formula was derived.

RESULT

Body surface area (mean ± standard deviation) was 2015.01 ± 1115.02 cm2 (median = 1841.40 cm2; range = 844.2-4043.12 cm2). The calculated K-constant was 14.9 for the six Atlantic Stingrays, and the CT-derived BSA formula was as follows: BSA (cm2) = 14.9 × (BW, g)2/3.

CONCLUSION

These results provide a method for calculating BSA in Atlantic Stingrays. The CT-derived BSA formula can be used for allometric dosing of chemotherapeutic agents and other drugs in a clinical setting; in a broader sense, the formula can be applied to studies of nutrition, metabolic rate, and physiology.

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.

Case series: Lymphoid neoplasia in three elasmobranch species

Elasmobranchs (sharks and rays) are charismatic cartilaginous fish, popular in public aquaria. Almost 200 shark and ray species are listed as threatened by the International Union for Conservation of Nature (IUCN), demonstrating the importance of captive breeding and research programmes. Limited studies investigate diseases of elasmobranchs in captive and free-living environments, and among available literature neoplasia is rarely reported, with even fewer cases of lymphoid neoplasia documented. This article outlines the first reports of lymphoid neoplasia in three elasmobranch species in which haematopoietic neoplasms have not been reported to date. It summarizes signalment, history and histopathologic findings in an undulate ray, Raja undulata (Lacepede), a common smooth-hound, Mustelus mustelus (Linnaeus) and a bat ray, Myliobatis californica (Gill). Lesions were confirmed in a wide range of tissues and evidence of lymphoid leukaemia was seen in two cases. This small-scale review demonstrates that lymphoid neoplasia should be considered as a differential diagnosis in elasmobranchs presenting with lethargy and anorexia and highlights the challenges of immunohistochemical work up.

Epizootic neoplasia in a managed population of Atlantic bumper fish, Chloroscombrus chrysurus (Osteichthyes: Carangidae), at a public aquarium

Advances in fish medicine and husbandry have increased the average lifespans of specimens in managed aquarium populations. As a result, an increased incidence and variety of neoplasia is expected. This work characterizes diverse neoplasms arising within a managed population of Atlantic bumper fish acquired via repeated collections from the Charleston Harbor region. A total of 76 neoplasms were evaluated histologically from 41 of 45 fish that died or were killed over a 46-month period, including cutaneous hemangiomas and hemangiosarcomas, lepidocytomas and lepidosarcomas, fibromas, vertebral body or cutaneous osteomas, disseminated lymphomas, testicular leiomyomas, cutaneous or branchial fibrosarcomas, myxomas, fibroblastic lepidosarcoma, teratoid medulloepithelioma, ganglioglioma, malignant nerve sheath tumour, cardiac rhabdomyoma, cutaneous rhabdomyosarcoma, soft tissue sarcoma and renal adenoma. Perioral and cutaneous lesions of vascular and scale origin were observed most frequently. Other, often malignant, neoplasms arose within these benign lesions, resulting in extensive local tissue invasion. However, excluding disseminated lymphomas, metastasis was only detected in one case of hemangiosarcoma. These findings suggest early surgical intervention may limit tissue destruction and loss of display quality. This report details a variety of common and rare neoplasms in fish, as well as the first characterizations of neoplasia in Atlantic bumper and ganglioglioma in fish.