title: Severe thymic hyperplasia in a newborn calf associated with impaired T-cell differentiation.
abstract: A 1-day-old female Holstein-Friesian calf was presented for severe dyspnea. Physical examination revealed respiratory distress, moderate edema of the ventral neck, and swollen jugular veins. The calf died and was submitted for necropsy. A severely enlarged thymus (40 cm × 20 cm × 10 cm) weighing 1.37 kg was detected on gross examination. Histomorphology was normal but no tingible body macrophages were observed in the medullary areas. Immunohistochemistry was characterized by the lack of thymic cluster of differentiation 3 and major histocompatibility complex class II expression compared to age-matched controls. The findings were consistent with severe thymic hyperplasia, a rare congenital condition that is also described in children. Immunohistochemical findings were suggestive of impaired T-cell development and selection associated with lack of apoptosis of thymic cells (lack of tingible body macrophages). Thymic hyperplasia in juvenile animals should be considered among the differential diagnoses of mediastinal masses as a rare cause of respiratory distress in newborn calves.
authors.affiliation: 1Diana Binanti, Department of Veterinary Science and Public Health, Faculty of Veterinary Medicine, Veterinary University Hospital, Pathology Unit, Università degli Studi di Milano, 26900, Lodi, Italy. diana.binanti@unimi.it.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Fantinato
authors.forename: Davide
authors.initials: D
authors.lastname: Pravettoni
authors.forename: Annalisa
authors.initials: A
authors.lastname: Forlani
authors.forename: Pietro
authors.initials: P
authors.lastname: Riccaboni
authors.forename: Diana
authors.initials: D
authors.lastname: Binanti
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D017252:CD3 Complex / Q000032:analysis; D002417:Cattle; D002418:Cattle Diseases / Q000473:pathology*; D002454:Cell Differentiation / Q000502:physiology; D017809:Fatal Outcome; D005260:Female; D000949:Histocompatibility Antigens Class II / Q000032:analysis; D007150:Immunohistochemistry / Q000662:veterinary; D013601:T-Lymphocytes / Q000473:pathology*; D013952:Thymus Hyperplasia / Q000473:pathology / Q000662:veterinary*
chemical_list: D017252:CD3 Complex; D000949:Histocompatibility Antigens Class II
keywords: Calves; T-cell differentiation; immunohistochemistry; thymic hyperplasia