Joint Pathology Center Veterinary Pathology Services WEDNESDAY SLIDE CONFERENCE 2015-2016 C o n f e r e n c e 17 10 February 2016 Casey J. LeBlanc, DVM, PhD Diplomate, ACVP Clinical Pathologist & CEO KDL VetPath Knoxville, TN & Springfield, VA CASE I: TAMU-1-2013 (JPC 4033379). Signalment: 18-day-old thoroughbred colt (Equus caballus) History: A healthy newborn foal nursed and the next day, became lethargic and had hemoglobinuria. With progressive stupor, icterus, hyperbilirubinemia and anemia, the foal was presented to the clinic at 2 days of Mucous membranes, foal. The mucous membranes of this foal are extremely yellow, indicating icterus. (Photo age. courtesy of: Dept Vet Pathobiology, College Vet Med Texas A&M University, College Station, TX 77843-4467 Gross Pathology: Yellow mucous http://vetmed.tamu.edu/vtpb) membranes and tissues (icterus); ~200ml abdominal transudate with fibrin strands; Total bilirubin 14.5 mg/dl (0-1.9) myocardial mottling grey and red GGT 124U/L (0-53) (hemorrhage and necrosis) a small Thebsian Alkaline phosphatase 553U/L (128-512) vein in the noncoronary aortic sinus; urachus ALT 850U/L (134-643) patent. Saline agglutination test positive Mare serum Anti-Qab positive Laboratory Results: PCV=12 (32-53) no Nrbc’s Histopathologic Description: The section Platelets 470,000/ul (100-350,000) of liver has widespread atrophy of TP 4.7g/dl (5.3-7.3) hepatocytes with hypertrophied and 1 Liver, foal. There is extensive pigment deposition throughout the section, to include brown granules in hepatocytes (lipofuscin- yellow arrows), brown spicular material (acid hematin – green arrows) and distended bile canaliculi (cholestasis – black arrows). Syncytial hepatocytes, often with peripheralized nuclei are scattered throughout the section. (HE, 40X) occasionally binucleate nuclei. Some Contributor’s Morphologic Diagnosis: hepatocyte syncytia contain 6-8 nuclei. Often, the hepatocytes exhibit feathery Liver: Subacute hepatopathy with centrilo- degeneration, but centrilobular hepatocytes bular hepatocellular degeneration, necrosis are degenerating or have individual cell and collapse; edema, lipofuscinosis, bile necrosis. The spaces of Disse are expanded casts and mild bile duct proliferation; (edema), and sinus leukocytosis is common hepatocyte syncytia; erythrophagocytosis with leucocytes often concentrated in areas and hemosiderosis; multifocal neutrophilic of hepatocyte loss. Scattered lipofuscin- hepatitis. laden macrophages are often near the pale staining triads, and bile casts and mild bile Contributor’s Comment: This is a classic duct proliferation are noted. Throughout the case of equine neonatal isoerythrolysis section are syncytia similar to Langhan’s /isoimmune hemolytic anemia (NI). The type multinucleate giant cells with nuclei animal was treated with dexamethasone, surrounding a tan, granular cytoplasm banamine, and antibiotics; clinical and post- (lipofuscin). Erythrophagocytosis by mortem blood cultures were sterile. No Kupffer cells is noted, and iron-staining organisms were noted with Gram or GMS Kupffer cells are in sinusoids. Hepatic cords stains. While there is inflammation is in the are disassociated (shock). lesion, it was felt to reflect secondary, cholestasis-induced hepatitis. 2 When reviewing the case with the resident, growth factors.7 Just as in autoimmune the pathologist commented that the giant hemolytic anemia in early childhood, cells were classically seen with NI; syncytial cell hepatopathy has been reported however, the resident noted that this lesion in cases of equine NI.2 It was noted in a case is not mentioned in textbooks as a lesion of NI presented in the WSC of 5-14-86. associated with NI. Young horse How does one explain the lack of the lesion hepatocytes often form syncytia, and giant description? Foal livers in fatal cases of NI cell hepatopathies/ hepatidides are are “busy,” and the syncytial cells, while described; especially associated with lepto- typical, may be down-played in face of the spirosis,13,20 but “idiopathic” hepatocyte catastrophic clinical and autopsy findings. syncytia have been described in 5-7 month- Because our cases are often referral cases old, equine abortuses3 and have been seen and are subacute to chronic, it may also be by this contributor in leptospira PCR- that syncytia are just more frequent in long- negative cases. In human infants with standing, fatal cases. Syncytia are jaundice, it was described as “giant cell characteristic. Foals seem prone to respond hepatitis”17 or “syncytial giant cell this way. Although neonatal infections may hepatitis.15 Initially, some considered it an complicate clinical NI, infectious agents are expression of viral hepatitis, particularly not always documentable. We should serum hepatitis, in infancy. Some feel the remember that only recently a viral agent of lesion reflects a specific insult such as blood equine Theiler’s disease has been group incompatibility between mother and identified,4 which may play a role (though I infant. It has been considered a nonspecific doubt it). response of liver regeneration to any injury.10,19 Still others consider it a Kernicterus is always a concern in cases of congenital defect in the formation of bile prolonged unconjugated hyperbilirubinemia canaliculi or another genetically transmitted in neonates. This foal had no macroscopic abnormality.5,14 Popper and Schaffner14 lesions of kernicterus, the cortex did not concluded hepatocyte giant cell formation fluoresce and no neuronal lesions were was a feature of cholestasis in infancy, and noted in the cerebral cortex, Purkinje cells or that it may be associated with some inflam- hippocampus, where it has been described in matory changes. Syncytial cell hepatitis has foals with NI.12 It’s of interest that syncytia been reported in humans and is associated were not reported in any of their autopsy with bacterial sepsis (especially cases, even their chronic cases. There is a toxoplasmosis, syphilis listeriosis, case report of NI in a three-day-old foal with tuberculosis), viral diseases (cyto- kernicterus and neuronal necrosis megalovirus, herpes simplex, varicella, represented macroscopically by yellow- echovirus, parvovirus B19, enterovirus, discolored nuclei.6 rubella, human herpesvirus-6, human immunodeficiency virus, hepatitis types A, For completeness, it is interesting that this B and C, Marburg virus and paramyxo- colt had a persistent neutrophilia and virus), liver transplantation and death from developed a thrombocytosis. Alloimmune, severe liver failure.8,16 However, in the neonatal neutropenia has been described in a neonatal period it is considered a non- foal with Ka antibodies in a recent report of specific reaction of immature hepatocytes to NI.21 The most complete study of anti- various forms of “aggression,”10 and the erythrocyte antibodies in mare serum and syncytia stain with nuclear proliferation and colostrum was done in thoroughbred and 3 from opsonization of red blood cells by complement component C3b, or by antibody, followed by phagocytosis.18 Lipofuscin is an intracellular pigment thought to accumulate as a result of aging and cellular “wear and tear,” including processing of senescent cellular organelles and other material. It accumulates within lysosomes most significantly in post mitotic or slowly dividing cells as an end product of autophagy and is often seen as a perinuclear golden brown pigment. It looks very similar histologically to ceroid, which is more Liver, foal: There are moderate amounts of iron within Kupffer cells. (Perl’s, 40X) commonly associated with pathologic conditions such as severe malnutrition and vitamin E deficiency or can be seen in standardbred mares and Qa and Aa seemed certain inherited conditions such as neuronal to be the most common alloantibodies found 1 ceroid lipofuscinosis (see WSC 2015-16, at large; however, these alloantibodies may conference 10, case 1). Ceroid is known to not be the most common seen in clinical 2, 9 accumulate in both Kupffer cells and cases of NI. Alloantibodies to Qa antigens hepatocytes as well as other tissues and can were found in the mare of our case. The colt be intracellular or extracellular. Lipofuscin of our study did not show a regenerative is thought to accumulate slowly over the life erythroid response. Over the 2-week of the animal, whereas ceroid usually hospitalization, no nucleated erythrocytes accumulates rapidly depending on the were noted and the bone marrow had associated condition. Histochemical tech- erythrocytic hypoplasia. We wondered if niques which can aid in identifying both this may have reflected a specific ceroid and lipofuscin include Sudan black, destruction of precursors of the erythroid oil-red-O, PAS and Ziehl-Neelsen stains. series. Although differences in content of the two pigments have been demonstrated by special JPC Diagnosis: Liver: Hepatocellular histochemical techniques, it is not possible degeneration and atrophy, diffuse, severe to differentiate the two pigments in standard with Kupffer siderosis, cholestasis, and H&E stained sections.11 hepatocellular syncytial cell formation. The primary histologic features in this case include hepatocyte degeneration and Conference Comment: Neonatal iso- atrophy, with formation of syncytial cells. erythrolysis is a type II hypersensitivity Extensive pigmentation of hepatocytes and reaction that results from antibodies directed Kupffer cells was present throughout the against neonatal red blood cells, most section prompting extensive discussion. frequently