CONGENITAL NEOPLASMS IN BOVINE ABORTED FETUSES AND NEONATES: A MULTI-INSTITUTIONAL CASE SERIES

EMILIANO SOSA; FEDERICO GIANNITTI; MELISSA MACÍAS-RIOSECO; LUIS COLQUE CARO; MARIA VALERIA SCIOLI; ELEONORA LIDIA MORRELL; FRANCESCA CHIANINI; GERMÁN JOSÉ CANTÓN

Congreso; XIII Reunión Argentina de Patología Veterinaria; 2023

Bovine abortion and neonatal death result in important production losses and are of welfare concern in the livestock industry. The causes of bovine abortion are not identified in ~40-70% of the cases subjected to laboratory diagnostic investigation. Non-infectious causes are thought to contribute significantly to these losses but given that they represent a major diagnostic challenge, they are difficult to quantify. Congenital neoplasms are rare and related to genetic and/or environmental factors. We report ten cases of neoplasia in bovine aborted fetuses (6 cases) and neonates (4 cases) in Argentina (cases 1-2), Uruguay (cases 3 and 6), UK (cases 4-5), and USA (cases 7-10). All cases were examined and autopsied. Tissue samples were fixed in 10% buffered formalin and stained with H&E. Immunohistochemistry (IHC) against different markers were applied in some cases. Case 1 was a beef breed fetus aborted at 7 months of gestation with multifocal 0.1-0.2 cm nodular lesions in the liver, lungs, kidneys, and spleen. Histologically, a B-cell lymphosarcoma (neoplastic proliferation of round cells with a CD79a+ and CD3- phenotype as determined by IHC) was identified in the lung, spleen, liver, kidney, and adrenal glands. Case 2 was a 7-month Holstein fetus with superficial and internal lymphadenomegaly and hepatosplenomegaly. Neoplastic round cells morphologically compatible with lymphosarcoma infiltrated the lung, liver, heart, and kidney. No IHC was performed to further characterize the neoplastic cells. Case 3 was an 8-month male Holstein fetus with numerous, firm, irregularly shaped, tan pale or red mottled, raised, exophytic, 0.2-7.0 cm nodules disseminated in the peritoneum, omentum, serosal surfaces of the abdominal and pelvic viscera, and tunica vaginalis of the testes. Histologically these nodules consisted of epithelioid cells positive for pancytokeratin and negative for vimentin, supported by a fibrovascular stroma forming papillary projections, typical of mesothelioma. Case 4 was a 9-month fetus with hepatomegaly and nephromegaly. Histology and IHC revealed a B-cell lymphosarcoma with CD79a+, Pax5+, CD20+ and CD3- cells mainly affecting the kidneys, lungs, liver, and meningeal vasculature. Case 5 was a 9-month-old fetus (no breed reported). Autopsy only revealed lesions consistent with dystocia. A malignant round cell neoplasm with neoplastic cells immunonegative for CD79a, Pax5, CD20 and CD3 was diagnosed microscopically in the liver, lungs and heart, and within vessels in the brain and thyroid gland. Case 6 was a 1-day-old male Holstein neonate with an exophytic, multinodular cauliflower-like neoplasm measuring 5.0×4.7×3.4 cm expanding the lower lip, with a histologic diagnosis of lymphangioma. Case 7 was a 16-dayold Holstein calf. Grossly, the left papillary muscle of the heart was multifocally effaced by 0.1-0.2 cm soft nodules, histologically consistent with adenomatoid tumor. Neoplastic cells were positive for vimentin and pancytokeratin, and negative for Factor VIII. Case 8 was a 5-day-old Jersey calf with a focal myocardial adenomatoid tumor, also. Case 9 was a female beef fetus with an 18.0×11.0 cm diameter ovarian tumor with a thick capsule and multiple roughly spherical nodules on cut section. Microscopically, the tumor was consistent with a sex cord stromal tumor. Case 10 was a 16-day-old Holstein calf with multiple nodules expanding the abdominal cavity, the serosal surfaces of the spleen and liver, and attached to the mesentery. A diagnosis of mesothelioma was set on morphologic grounds and positive immunoreactivity of neoplastic cells to pancytokeratin. Congenital neoplasms are rare in cattle and are most often diagnosed as lymphomas, mesotheliomas, and hamartomas. Other neoplasms such as myocardial adenomatoid tumors, vascular neoplasms (lymphangioma, hemangioma and hemangiosarcoma), tumors of the gonads (Sertoli cell tumors, Leydig interstitial cell tumors), nephroblastoma, cutaneous mast cell tumors, and tumors of the nervous system are less frequently reported. Further studies are needed on the causes and pathogenesis of congenital neoplasms in cattle.