Retinoblastoma in the eye of a llama (Llama glama)

Neoplasia and Proliferative Lesions of New World Camelids: A Systematic Literature Review and Retrospective Study of Cases Submitted to Colorado State University From 1995 to 2020

Camelid pathology submissions to veterinary diagnostic laboratories are on the rise given the increasing popularity and population of llamas and alpacas especially in the western United States. When compared to other animals, the field of camelid neoplasia has a relative paucity of cases reported in the literature. The Colorado State University Veterinary Diagnostic Laboratories (CSU-VDL) has had a steady increase in the numbers of camelid pathology submissions allowing for a robust review of diagnoses of neoplasia in new world camelids. Here we present a retrospective analysis of camelid neoplastic and proliferative lesions diagnosed at the CSU-VDL from 1995 to 2020, followed by an extensive literature review. Results show increasing incidence of camelid neoplasia reported in the literature, therefore becoming a common diagnosis in llamas and alpacas. Proliferative and neoplastic lesions were diagnosed in 8.8% of new world camelid submissions to CSU-VDL with the most common tumors being lymphomas, squamous cell carcinomas, fibromas, and adenocarcinomas. Risk factors are female sex and increased age except in the case of lymphoma, which tends to occur in younger camelids. Lymphomas, melanomas, and adenocarcinomas (especially of gastrointestinal tract) carry an increased risk of multiple-organ system involvement often with widespread metastases. Conditions described in camelids for the first time include osteosarcoma, cutaneous hemangiosarcoma, myxosarcoma, pilomatricoma, ovarian theca cell tumor, congenital nevus with malignant transformation, and various other neoplasia. This article will provide an operational guide for camelid neoplasia to further assist veterinary laboratory diagnosticians, researchers, and practicing veterinarians in the field of camelid medicine and pathology.

Retrobulbar embryonal tumor with multilayered rosettes in a golden retriever dog

Although rare, embryonal tumors (previously called primitive neuroectodermal tumors) should be considered in the differential diagnosis of retrobulbar tumors in dogs regardless of the age of the patient, and ancillary tests are required for definitive diagnosis.

Conservative management of retinoblastoma: Challenging orthodoxy without compromising the state of metastatic grace. "Alive, with good vision and no comorbidity"

Retinoblastoma is lethal by metastasis if left untreated, so the primary goal of therapy is to preserve life, with ocular survival, visual preservation and quality of life as secondary aims. Historically, enucleation was the first successful therapeutic approach to decrease mortality, followed over 100 years ago by the first eye salvage attempts with radiotherapy. This led to the empiric delineation of a window for conservative management subject to a "state of metastatic grace" never to be violated. Over the last two decades, conservative management of retinoblastoma witnessed an impressive acceleration of improvements, culminating in two major paradigm shifts in therapeutic strategy. Firstly, the introduction of systemic chemotherapy and focal treatments in the late 1990s enabled radiotherapy to be progressively abandoned. Around 10 years later, the advent of chemotherapy in situ, with the capitalization of new routes of targeted drug delivery, namely intra-arterial, intravitreal and now intracameral injections, allowed significant increase in eye preservation rate, definitive eradication of radiotherapy and reduction of systemic chemotherapy. Here we intend to review the relevant knowledge susceptible to improve the conservative management of retinoblastoma in compliance with the "state of metastatic grace", with particular attention to (i) reviewing how new imaging modalities impact the frontiers of conservative management, (ii) dissecting retinoblastoma genesis, growth patterns, and intraocular routes of tumor propagation, (iii) assessing major therapeutic changes and trends, (iv) proposing a classification of relapsing retinoblastoma, (v) examining treatable/preventable disease-related or treatment-induced complications, and (vi) appraising new therapeutic targets and concepts, as well as liquid biopsy potentiality.

Metastatic cholangiocarcinoma in a llama (Lama glama)

A 2-year-old female llama ( Lama glama), from a private zoological park, with anorexia, ataxia, dyspnea, ascites, and emaciation, was necropsied. Gross inspection, and cytological, histological, and immunohistochemical analyses were performed. A firm, white, multinodular mass, 25 cm in diameter was found in the liver parenchyma. Similar nodules up to 3 cm were found in lymph nodes, lung, diaphragm, and peritoneum. Histologically, the affected organs were replaced by an infiltrative growth of undifferentiated neoplastic cells. Immunohistochemically, neoplastic cells were positive for pancytokeratin (panCK), CK20, and CK19, and negative for thyroid transcription factor 1, CK7, and carcinoembryonic antigen. A diagnosis of poorly differentiated metastatic cholangiocarcinoma was made.

Evaluation of toxicity after periocular and intravitreal administration of carboplatin in rabbit eyes

The aim of this study was to characterize the extent of toxicity of focal carboplatin administration and to identify the dose limiting toxicity in rabbit eyes depending on administered concentrations. New Zealand white male rabbits (n = 18) were treated with 1 of 3 regimens: a single periocular injection of 15 mg of carboplatin (group I), a single periocular injection of 30 mg of carboplatin (group II) and a single transcorneal intravitreal injection of 0.05 mg of carboplatin (group III). Ophthalmologic examinations and vitreous samplings were performed under dissociative anaesthesia at regular intervals during next 2 (groups I and III) or 3 (group II) weeks. Carboplatin concentrations in vitreous samples were assessed by atomic absorption spectroscopy. At the end of experiments, all rabbit eyes were obtained for histopathologic examination. Clinical and histological evidence of toxicity was graded into four grades according to anatomical structures of the rabbit eye. The dose limiting toxicity was reached in group II after periocular injection of 30 mg of carboplatin and in group III after intravitreal injection of 0.05 mg of carboplatin. No systemic toxicity was observed in any group. Focal carboplatin administration may decrease systemic exposure to this cytotoxic drug in the retinoblastoma treatment. This moreover suggests that focal carboplatin administration is a promising approach and challenge for advanced retinoblastoma chemotherapy.

miR than meets the eye

Retinoblastoma is a rare pediatric cancer that has served as a paradigm to investigate the mechanisms of tumorigenesis. In this issue of Genes & Development, Conkrite and colleagues (pp. 1734-1745) found high levels of the miR-17~92 and miR-106b-25 microRNAs in primary retinoblastomas and show that overexpression of miR-17~92 accelerates retinoblastoma development in mice by promoting proliferation, in part by reducing expression of the cell cycle inhibitor p21. These experiments identify the RB/miR-17~92/p21 axis as a critical regulator of retinoblastoma tumorigenesis and potentially many other cancers.

Bilateral intraocular malignant neuroectodermal tumors in a telescope goldfish (Carassius auratus)

Abstract A 5-year-old male telescope goldfish (Carassius auratus) developed buphthalmia of the left eye. An enucleation was performed and a diagnosis of a neuroectodermal tumor was made on histological examination. Although the fish initially recovered, it was killed 49 days postsurgery due to a severe decline in its condition. On histological evaluation of postmortem tissue samples, it was determined that the fish also had a neuroectodermal tumor of the right eye with local invasion of the brain. On immunohistochemistry, the neoplastic cells were positive for S-100. To the authors' knowledge, this is the first published case of naturally occurring bilateral intraocular neuroectodermal tumors in a fish.

Ophthalmology of South american camelids

In the past 10 years, information about South American camelid anatomy, physiology, medicine, and surgery has increased exponentially, including information about the eye. Although trauma-related diseases are the most common eye problems for which camelids are presented to veterinarians, there have recently been many anecdotal reports and published case reports of camelids having ocular malignancies and potentially hereditary ocular abnormalities. The increased number of ocular diseases being reported may be because of increased recognition of camelid diseases or an increase in these diseases as a result of restricted gene pools as a consequence of inbreeding. As the popularity of camelids is steadily increasing, owners are becoming more knowledgeable about their animals, and there is more need for veterinarians who understand their ocular anatomy, physiology, disease susceptibility, and recommended treatments. This article provides the relevant information about the eye.

Neuronal Embryonal Tumors in Fish

This article describes 11 cases of neuronal embryonal neoplasia in captive adult teleost fish. Neoplasms were located within 1 or both eyes of 8 fish and the skin of 3 other fish. Ocular neoplasms most often presented as unilateral or bilateral exophthalmia. Seven ocular and 1 cutaneous mass were composed of small triangular (carrot-shaped) neoplastic cells with Flexner-Wintersteiner-type rosette formation. Mass location and histologic and ultrastructural features were suggestive of retinoblastomas. One ocular mass was composed of ribbons and rosettes of neoplastic cells with multiple areas of neuronal differentiation and was diagnosed as a teratoid medulloepithelioma. A cutaneous mass from an electric eel ( Electrophorus electricus) consisted of rosettes and streams of elongate neoplastic cells. The epidermal electroreceptor (ampullary) organ was considered as an origin. Although distant metastases were not observed, neoplasms were generally locally aggressive with postexcision recurrence. There was occasional spread to or de novo occurrence within the contralateral eye.

Malignant round cell neoplasia in llamas and alpacas

Malignant round cell neoplasia was identified in 12 llamas and 12 alpacas aged 0-23 years. Mean age of affected alpacas (3.1 years) was significantly less than that of affected llamas (8.0 years). Tumor cell morphology varied from large and often pleomorphic (11 tumors) to small and often homogeneous (13 tumors). Neoplastic lesions were multicentric in 12 cases. Other sites were gastric (5 cases), intra-abdominal (perirenal; 4 cases), intrathoracic (2 cases), and cervical (1 case). Immunohistochemistry with antibodies to CD79alpha, BLA36, and CD3 identified B-cell lymphoma (12 cases) and T-cell lymphoma (6 cases). Six tumors did not express any lymphoid marker and were further immunostained for neuron-specific enolase (NSE), synaptophysin, S-100, glial fibrillary acidic protein (GFAP), and chromogranin A. All 6 of these tumors were negative for GFAP and chromogranin A but expressed 1 or more of the neural markers NSE, synaptophysin, and S-100 and were classified as primitive malignant round cell tumors (PMRCT). Tumor types could not be distinguished on the basis of animal age, gross pathologic appearance, tumor morphology, or tumor location. All animals with lymphoma and 5 with PMRCT died or were euthanatized. One alpaca with a focal cervical PMRCT lived for at least 20 months after diagnosis. Results of this study indicate that malignant round cell tumors in llamas and alpacas are a heterogeneous group that cannot be distinguished on the basis of signalment, postmortem findings, or routine light microscopic findings. Immunohistochemistry is a valuable diagnostic procedure when evaluating malignant round cell neoplasia in llamas and alpacas.

Prevalence of neoplasia in llamas and alpacas (Oregon State University, 2001-2006)

Prevalence and type of neoplastic disease were determined in 551 camelid submissions (368 alpacas [Lama pacos], 180 llamas [Lama glama], and 3 cases in which species was not identified) over a 5-year period. Forty neoplasms were identified in 38 animals (6.9%). Prevalence of neoplasia in llamas was higher (11%) than in alpacas (4.9%). Mean age of camelids with neoplasia was 9.42 +/- 4.9 years. Mean age of alpacas with neoplasia (5.48 +/- 3.7 years) was significantly less than of llamas with neoplasia (12.53 +/- 3.2 years; P < 0.001). Cutaneous and mucocutaneous fibroma/fibropapilloma was most common (10 animals), followed by cutaneous and mucocutaneous squamous cell carcinoma (6 animals), disseminated lymphoma (5 animals), and fibrosarcoma (4 animals). Four of 5 animals with lymphoma were alpacas, aged 0.21 to 4 years. Lymphoma occurred in 1 aged llama (15 years). Disseminated carcinoma and adenocarcinoma occurred in 4 llamas and 2 alpacas, and included biliary (2), gastrointestinal (2), mammary gland (1), and unknown (1) origin. Mean age of camelids with any type of carcinoma or adenocarcinoma (12.36 +/- 2.8 years) was significantly greater than that of camelids with lymphoma (4.24 +/- 6.2 years; P = 0.02). Results indicate that neoplasia is relatively common in camelids and that there are differences between llamas and alpacas as regards prevalence of neoplasia, tumor types, and age at diagnosis.

Rb induces a proliferative arrest and curtails Brn-2 expression in retinoblastoma cells

BACKGROUND

Retinoblastoma is caused by loss of the Rb protein in early retinal cells. Although numerous Rb functions have been identified, Rb effects that specifically relate to the suppression of retinoblastoma have not been defined.

RESULTS

In this study, we examined the effects of restoring Rb to Y79 retinoblastoma cells, using novel retroviral and lentiviral vectors that co-express green fluorescent protein (GFP). The lentiviral vector permitted transduction with sufficient efficiency to perform biochemical analyses. Wild type Rb (RbWT) and to a lesser extent the low penetrance mutant Rb661W induced a G0/G1 arrest associated with induction of p27KIP1 and repression of cyclin E1 and cyclin E2. Microarray analyses revealed that in addition to down-regulating E2F-responsive genes, Rb repressed expression of Brn-2 (POU3F2), which is implicated as an important transcriptional regulator in retinal progenitor cells and other neuroendocrine cell types. The repression of Brn-2 was a specific Rb effect, as ectopic p27 induced a G0/G1 block, but enhanced, rather than repressed, Brn-2 expression.

CONCLUSION

In addition to Rb effects that occur in many cell types, Rb regulates a gene that selectively governs the behavior of late retinal progenitors and related cells.

Malignant nonteratoid ocular medulloepithelioma in a llama (Llama glama)

A 6-year-old female llama presented with buphthalmos of its right eye owing to the presence of an intraocular mass. The affected globe was enucleated and submitted for microscopic examination. The intraocular mass was diagnosed as malignant medulloepithelioma. Within the following months, the llama developed soft tissue masses, which completely filled the right orbital cavity and expanded the cranial portion of the right mandibular bone, and enlarged mandibular lymph nodes. Euthanasia was elected 30 months after the initial diagnosis. The carcass was submitted for postmortem examination, which revealed the presence of medulloepithelioma metastases within the right orbit, mandible, mandibular lymph nodes, lungs, liver, and mesenteric and sublumbar lymph nodes. The primary intraocular tumor and its metastases were composed of neoplastic undifferentiated neuroepithelial cells, which formed tubules, Flexner-Wintersteiner and Homer Wright rosettes, and rare solid sheets. Electron microscopy showed that tumor cells were connected by desmosome-like junctions and contained rare intracytoplasmic basal bodies. Neoplastic cells were positive for vimentin, nestin, microtubule-associated protein 1B, S-100 protein, and glial fibrillary acidic protein (GFAP). To the best of the authors' knowledge, this is the first report of a malignant nonteratoid ocular medulloepithelioma with distant metastases in a llama and of the ultrastructural and extended immunohistochemical characterization of a nonteratoid medulloepithelioma in this species.