Pesq. Vet. Bras. 38(11):2099-2108, novembro 2018 DOI: 10.1590/1678-5150-PVB-6079 Topic of General Interest Animais de Produção/Livestock Diseases ISSN 0100-736X (Print) ISSN 1678-5150 (Online)
PVB-6079 LD Gross and histopathological pitfalls found in the examination of 3,338 cattle brains submitted to the BSE surveillance program in Brazil1 Raquel R. Rech2, Paula R. Giaretta2, Corrie Brown3 and Claudio S. L. Barros4*
ABSTRACT.- Rech R.R., Giaretta P.R., Brown C. & Barros C.S.L. 2018. Gross and histopathological pitfalls found in the examination of 3,338 cattle brains submitted to the BSE surveillance program in Brazil. Pesquisa Veterinária Brasileira 38(11):2099-2108. Faculdade de Medicina Veterinária e Zootecnia, Universidade Federal de Mato Grosso do Sul, Av. Senador Filinto Müller 2443, Campo Grande, MS 79074-460, Brazil. E-mail: [email protected] Gross and histopathological pitfalls found in the examination of 3,338 cattle brains This study stems from the findings during the gross and histopathological exam of submitted to the BSE surveillance program in 3,338 cattle brains as part of the bovine spongiform encephalopathy (BSE) active surveillance programof Santa Mariaof the Brazilianwhich at theMinistry time of(2001-2007) Agriculture, was Livestock, the national and Supply reference from laboratory2001 to 2005. for Brazil The work was carried out in the Veterinary Pathology Laboratory of the Federal University
the diagnosis of BSE and other transmissible spongiform encephalopathies. Both gross and histopathological aspects are described. Several gross aspects were annotated: anatomic normal structures not commonly recognized (non-lesions), lesions of no clinical significance, [Ciladas macroscópicas e histopatológicas encontradas postmortem changes and artifacts; all these can amount to important pitfalls that distract no exame de 3.338 encéfalos de bovinos submetidos ao the pathologist during the routine gross examination of the central nervous system (CNS). Rech R.R., Giarettaprograma P.R., Brown de vigilância C. & Barros da EEB C.S.L. no Brasil].2099- Accordingly, equivalent pitfalls were described in the histological examination. Non-lesions 2108 observed were the pineal body, embryo remnants such as the external germinal layer of the cerebellum, subependymal plates, and clusters of neuroblasts in the basal ganglia; or circumventricular structures such as area postrema, subcomisural organ, and melanosis in the leptomeninges and vessel walls. CorporaLesions amylaceawith little and or nocorpora clinical arenacea importance were includeddetected age-relatedrespectively inchanges astrocyte as processeslipofuscin, and hemosiderin, the pineal body. mineralization Cytoplasmic and neuronal hyalinization vacuolization of vessel was wallsobserved within in thethe redbrain nucleus and meninges. and habenular nucleus. Sarcocystis sp. without a correspondent
inflammatory reaction was rarely observed. Included within findings with no clinical manifestation were axonal spheroids and perivascular mononuclear cuffings. Changes in the CNS due to killing, sampling and fixation methods can obscure or distract from the more critical lesions. The ones related to the process of killing included hemorrhages caused in cattle destroyed by a captive bolt. Artifacts related to sampling and handling of CNS tissue consisted of inclusion of bone sand in the neural tissue from sawing the calvarium; dark neurons produced by excessive handling of the brain, and micro-organisms that contaminated the tissues during sampling or histological processing. Postmortem autolytic or putrefactive changes observed included vacuolar changes in the myelin sheath, clear halos surrounding neurons and oligodendrocytes, clusters of putrefaction bacilli within vessels or dispersed throughout the brain tissue associated or not to clear halos. One interesting, and somewhat frequent, postmortem autolytic change found in the bovine brain was the partial dissolution of the granule cell layer (GCL) of the cerebellum, also referred to as conglutination of the GCL 1 3 Accepted for publication on September 6, 2018. Received on August 28, 2018. 4 FaculdadeUniversity de of Medicina Georgia CollegeVeterinária of Veterinary e Zootecnia, Medicine, Universidade Department Federal deof 2 MatoPathology, Grosso 501 do D.W.Sul (UFMS), Brooks Av. Drive Senador Athens, Filinto Georgia Müller 30602, 2443, USA. Campo Grande, Part of the doctoral thesis of the first author. [email protected] Department of Veterinary Pathobiology, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843-4467, USA. MS 79074-460, Brazil. *Corresponding author: 2099 2100 Raquel R. Rech et al.
or as the French denomination “état glace”. Due to the shortage of comprehensive publications in the subject, this review is intended to address the main pitfalls that can be observed in the brain of cattle hoping to help other pathologists avoiding misinterpret them. INDEX TERMS: Postmortem findings, histopathology, pitfalls, cattle, brain, Brazil, central nervous system, artifacts, histology, neuropathology. RESUMO.- [Ciladas macroscópicas e histopatológicas encontradas no exame de 3.338 encéfalos de bovinos submetidos ao programa de vigilância da EEB no da camada de células granulares (CCG) do cerebelo, também Brasil. revisãoreferida pretende como conglutinação abordar as principaisda CCG ou ciladas“état glacé”. que possam Devido à escassez de publicações abrangentes neste assunto, esta ] Os resultados deste estudo foram obtidos pelo exame macroscópico e histopatológico de 3.338 cérebros de aparecer no cérebro de bovinos, na esperança de ajudar outros bovinos examinados durante o programa de vigilância ativa patologistas a evitar interpretá-las erroneamente. da encefalopatia espongiforme bovina (BSE) do Ministério TERMOS DE INDEXAÇÃO: Achados de necrópsia, histopatologia, Veterináriada Agricultura, (LPV) Pecuária da Universidade e Abastecimento Federal (MAPA), de Santa de Maria 2001 encéfalo, bovinos, Brasil, sistema nervoso central, artefatos, histologia, (UFSM)a 2005. O que, trabalho de 2001 foi realizadoa 2007, foi no o Laboratório laboratório denacional Patologia de neuropatologia. INTRODUCTION descritasreferência estruturaspara o diagnóstico anatômicas da BSE normais e de outras (não-lesões), encefalopatias mas espongiformes transmissíveis. Macroscopicamente, foram Identification of artifacts, normal structures that resemble lesions, lesions that are not associated with clinical signs, and Essesque são, achados com frequência, podem confundir interpretadas e desviar como lesões;a atenção lesões do postmortem changes, are an important aspect of diagnosing sem significado clínico; alterações pós-mortais e artefatos. central nervous system (CNS) diseases, allowing for correct interpretation of clinical features of the disease. These changes patologista durante o exame de rotina do sistema nervoso are grouped in four main categories: non-lesions, lesions of corpocentral pineal, (SNC). remanescentesDa mesma forma, embrionários, estruturas equivalentes como a camada foram no clinical significance, postmortem changes, and artifacts. descritas no exame histológico. As não-lesões observadas foram In the non-lesions category are included morphologic aspects of the CNS examination that might be interpreted as lesions germinativa externa do cerebelo, placas subependimárias contributewhen the pathologist to the altered is not clinical thoroughly state familiarof the animal with the and CNS. so e aglomerados de neuroblastos nos gânglios da base; ou Lesions of no clinical significance include those that do not estruturas circunventriculares, como área de postrema, órgão subcomissural e melanose em leptomeninges e paredes dos Postmortem deathare only as incidentala result of atautolysis necropsy or orputrefaction. histologic examination.Artifacts can vasos. Lesões com pouca ou nenhuma importância relacionadas changes are not real lesions, but occur after ao envelhecimentoCorpora incluíram amylacea lipofuscina, foram hemossiderina,detectados em mineralização, hialinizaçãocorpora das paredes arenacea dos, vasosno corpo do encéfalo pineal. be produced due to killing, sampling and fixation methods. Adicionalmente,e das meninges. foi observada vacuolização no citoplasma becameDuring indispensable the high of the to achieve worldwide reliable concern surveillance with BSE, of the deprocessos neurônios astrocíticos do núcleo e vermelho e do núcleo habenular. disease.examination This of study a large stems number from of the bovine alterations brains (Wells described et al. above1991) Sarcocystis
sp. sem reação inflamatória correspondente foi during the gross and histopathological exam of 3,338 cattle raramente observado. Incluídos nos achados sem manifestação brains as part of the bovine spongiform encephalopathy clínica estavam esferóides axonais e manguitos mononucleares (BSE) active surveillance program of the Brazilian Ministry of perivasculares. Alterações no SNC causadas pelo método de abate, Agriculture, Livestock, and Supply (MAPA) from 2001-2005. amostragem e fixação podem simular ou obscurecer lesões mais Due to the shortage of comprehensive publications in the dardoimportantes. cativo Aquelasou por punção relacionadas por faca ao métododa medula de abate na articulação incluíram subject this review is intended to address the main pitfalls hemorragias causadas em bovinos dessensibilizados pelo that can be observed in the brain of cattle hoping to help other pathologists avoiding misinterpret them. deatlanto-occipital. osso no tecido neuralArtefatos em relacionados consequência à do amostragem uso de serra e MACROSCOPIC EXAMINATION OF THE BRAIN manuseio de tecido do SNC consistiram na inclusão de pó Non-lesions para abrir a caixa craniana; neurônios escuros produzidos pelo manuseio excessivo do cérebro e micro-organismos melanosisIn the adult occurs cow as and a non-lesion sheep, leptomeningeal in cattle in Brazil, melanosis in breeds is a que contaminaram os tecidos durante a amostragem ou frequent normal finding (Innes & Saunders 1962a). Leptomeningeal processamento histológico. Alterações autolíticas pós-mortais ou de putrefação incluíram vacuolizações na bainha de mielina, with pigmented skin such as Nelore and pigmented skin and dispersoshalos claros em em todo torno o tecido dos cerebral,neurônios relacionados e oligodendrócitos, ou não a overdark thehair frontal coats suchlobes as ( Angus. Melanosis is characterized by aglomerados de bacilos de putrefação dentro dos vasos ou black or dark brown areas in the leptomeninges, especially e relativamente frequente encontrada foi a dissolução parcial Fig.1A) where it is frequently mistaken halos claros. Uma alteração autolítica pós-mortal intrigante by cortical necrosis. This normal finding is also frequently seen in the brains of sheep from the breeds Suffolk and Pesq. Vet. Bras. 38(11):2099-2108, novembro 2018 2101
Gross and histopathological pitfalls found in the examination of 3,338 cattle brains submitted to the BSE surveillance program in Brazil
A B Fig.1.of the Macroscopic midbrain and examination the thalamus. of the Caudal brain. colliculi( ) Frontal, (CC). parietal (C and occipital lobes of the brain with focally extensive leptomeningeal melanosis, a common normal finding in the bovine brain. See Figure 3F for histological appearance. ( ) Location of the pineal glandD) (P)Artifact just rostraldue to tothe the use rostral of a captive colliculi bolt (RC) to ) Artifact due to the use of a captive bolt to insensibilize cattleE) Artifact before associated death by bleeding. with the Locallytype of extensive area of subdural hemorrhage and a large fragment of bone is inserted in the brain parenchyma. ( F) Postmortem putrefaction. Crossstun cattle section before of the death brain by at bleeding. the level Diffuse of the basalsubdural nuclei. hemorrhage Multiple variably-sized is on the dorsal cavities and lateral in the encephalic brain parenchyma surfaces. (that resembles Swiss cheese. brain sampling. Air bubbles in the leptomeninges resulting from the ax’s blows at the calvarium when removing the brain. (
Artifacts due to the method of slaughter as to resemble a neoplasm (Summers et al. 1995). It occurs Hampshire Down, where they can form impressive aggregates the cranial cavity may create a variety of alterations in the The glandula pinealis The methods for killing and of removing the brain from principallystructure (Gartner in the leptomeninges & Hiatt 2007) over situated the frontal dorsally lobes. at the from the method of euthanasia and is observed in brains from brainstem between the rostral or pineal colliculi gland of mesencephalicis a glandular bovine brain. Subdural hemorrhage is a lesion that). A cancomplete result tectum and the thalamus ( ). It secretes melatonin and cattle that were killed by captive bolt (Fig.1C,D Fig.1B history in these cases is very important because it is difficult due to this glandular aspect that differs from the surrounding to differentiate these forms of hemorrhage from other causes neural tissue, may be mistakenly interpreted as a neoplasm, of traumatic hemorrhage. Many times, when using a captive especially on microscopic examination. bolt for slaughter, fragments of bone can be found within brain Pesq. Vet. Bras. 38(11):2099-2108, novembro 2018 2102 Raquel R. Rech et al.
tissue.This heavy This pressure can be attributed can send toemboli the heavy of brain pressure tissue intoexerted the by the captive bolt at the time of stunning (Coore et al. 2004). lungs and other organs such as liver (Garland et al. 1996). These emboli can assume several centimeters being promptly Artifactsvisible by duethe naked to sampling eye (Garland of the etbrain al. 1996).
The use of an axe for removal of the brain from the cranial vault produces bubbles in the leptomeninges. These bubbles are introduced in the leptomeningeal vessels while theembolism prosector ( hits ).the bone with the axe (Barros et al. 2006). These bubbles are sometimes mistakenly interpreted as gas PostmortemFig.1E changes
Postmortem changes include softening of the brain throughout, sometimes associated with the development of cavitiesa Swiss cheesecaused (by gases produced by the anaerobic bacilli ofcheese putrefaction. brain from This necrosis may give or other the brain true ante the mortemappearance lesion of Fig.1F). It is important to distinguish Swiss
(Auer et al. 2008). The would-be neuropathologists may be trapped in diagnosing cystic necrosis when facing this type of postmortem change. However, the yellow color of necrosis is absent and, unlike in necrosis, the internal surface of the “holes”MICROSCOPIC are smooth (Auer EXAMINATION et al. 2008). OF THE BRAIN bovine brain should be immersed in a volume of 10% neutral A) Medulla For optimal fixation for histopathologic examination, the Fig.2. Bovine brain hemisphere showing a systematic way to obtain representative samples for histologic examination. ( formalinan entire fixativebovine brain,that is 6 at liters least of ten 10% times neutral greater formalin than theare oblongata at the level of the obex, BO (1); Cerebellum, CE (2); volume of tissue to be fixed. Consequently, to adequately fix DiencephalonPons at the level at ofthe the level cerebellar of the peduncles,thalamus: parietalPO (3); Midbrainlobe, CP, A brain from an adult bovine will require about 2 to 5 days at the level of the rostral colliculi, ME (4); Occipital lobe, CO (5); needed. The time for fixation varies with the size of the brain. hippocampus, HC, andB thalamus, TA (6); and frontal lobe, CF, before reaching full fixation. The sections, except the ones in ofat thethe brainlevel inof the corpus. Red callosum dots = areaand postremabasal nuclei, (section NB (7). 1), Red dot = pineal gland. ( ) Cross sections obtained from sampling Figureout in a2 ,systematic are stained way. with To hematoxylin-eosin ensure representative (HE). analysis, red nuclei (section 4), habenular nuclei (section 6). Figure 2A Microscopic examination of the brain should be carried that both sides of serial transverse sections of 0.5 to 1cm diverse areas of brain are examined; it is recommended systematically processed from sections depicted in . be examined. The slides for histologic examination can be meningitis. In addition, these cells, as they migrate through Figure 2 molecularthe cerebellar layer cortex, (Innes can & beSaunders confused 1962b). with glial shruberries, This procedure has the following advantages: permits detailed a change seen when inflammatory cells accumulate in the studydescribe of specific the distribution areas of the of lesions.brain, offers consistent sections Subependymal plaques can be localized in the lateral and for comparison with control brains, and makes it easy to ventral portions of the lateral ventricles and can be erroneously Non-lesions plaque and the olfactory bulb, neuroblast accumulations, interpreted as ependymitis. Adjacent to the subependymal Normal microscopic structures that might be mistaken for ). lesions include some remnants of embryonic structure (external known as residual glia, can be seen and these could be confused layer of granule cells of the cerebellum, subependymal plaque), with areas of focal gliosis (Fig.3B circumventricular organs or normal pigment in the vessels Circumventricular organs are specialized centers that share ofnormally the leptomeninges found in fetuses, (melanin and calvesproduced up to by a melanocytes). few months of two morphologic characteristics - periventricular location The external granule cell layer of the cerebellar cortex is and vasculature lacking the typical blood-brain barrier organization (Duvernoy & Risold 2007, Vandevelde et al. 2012, age (Fig.3A). As the animal ages, these cells migrate toward Wohlsein et al. 2013). Circumventricular organs include: the granule cell layer. In cattle, complete disappearance of which(a) subcommissural is located on organ, the ventral a local modification surface of the of ependymal posterior this layer occurs between 12 and 18 months of age (Barros cells that projects into the mesencephalic aqueduct and 1980). This external granule cell layer can be confused with Pesq. Vet. Bras. 38(11):2099-2108, novembro 2018 2103
Gross and histopathological pitfalls found in the examination of 3,338 cattle brains submitted to the BSE surveillance program in Brazil
A B) The Fig.3. Non-lesions of the bovine brain. ( ) The external granular cell layer is a mantle of germinative cells found in fetal, neonatal and young animals. Few germinative cells appear in the molecullarC layer as they migrate towards the granular cell layer. HE, obj.20x. ( subependymal plaque consists of multifocal aggregates of germinative cells placed between the ependymaD) The areaand thepostrema parenchyma is one of the brain at the level of the lateral ventricles. HE, obj.20x. ( ) The subcomissural organ resembles a glandular arrangement with multiple acini formed by columnar cells with vacuolatedE cytoplasm and basally located nuclei. HE, obj.20x. ( circumventricular organs, located at the dorsomedial aspect of the medulla oblongata (seeF Fig.2B). It is composed of neuropil intermixed with the abundant vasculature. HE, obj.20x. ( ) Histologically, the pineal gland or epiphysis is composed of pinealocytes intermixed with interstitial cells, giving a hypercellular appearance to the parenchyma. HE, obj.10x. ( ) In leptomeningeal melanosis, the melanocytes are linearly distributed along the leptomeninges and can occasionally extend in the perivascular spaces of the peripheral areas of the cerebral parenchyma. HE, obj.40x. the caudal portion of the roof of the fourth ventricle and it is observed microscopically when a section of the medulla commissure just caudal to the pineal gland; (b) area postrema, ). In humans, the an agglomeration of glial cells and small capillaries located dorsally to parasympathetic nucleus of the vagus at the level centeroblogata and is it taken is there at level that chemoreceptorsof the obex (Fig.3D are located that will of the medulla; and (c) the pineal gland. The subcommissural function of the area postrema has been defined as the vomition (organ functions to secrete aldosterone (Duvernoy & Risold Leslie & Osborne 1984). Also, the area postrema functions epithelial2007). Because neoplasm, of the especially glandular whenstructure it is seen histologicallyin an oblique instimulate cardiovascular vomiting control, subsequent as the to intoxicationcells here will (Borison respond 1974, to sectionFig.3C), of this the organ thalamus. could Thebe erroneously area postrema interpreted is located as anin
angiotensin II (Barnes & Ferrario 1980). In histologic sections, Pesq. Vet. Bras. 38(11):2099-2108, novembro 2018 2104 Raquel R. Rech et al.
several microns to several millimeters in diameter. These capillaries are very prominent, it could be confused with a concretions are called corpora arenacea, acervuli cerebri, or the area postrema can be mistaken for gliosis, or when the dorsocaudal aspect of the epithalamus of the diencephalon, vascular neoplasm. The pineal gland is an evagination of the brain sand (Fuller & Burger 2007). They are formed from concentric dark laminations rich in protein alternating with which it is hold through a prolongation that contains the small lightercalcium layers and phosphorous rich in calcium. as theMineral principal structure constituents. consists recessand blood of the vessels third butventricle. contains The no pineal true neurons. gland is derivedPinealocytes from morphologically of hydroxyapatite and carbon apatite, with neuralsynthesize epithelium, melatonin and fromconsists serotonine of glial cellsand pinealocytes,also contain ). These concretions generally localize between the nervous fibers (axons) and occasionally within glial cells (Fig.4C norepinephrine and thyrotropin releasing hormone (Gartner). The laminations could correspond to fluctuations of the & Hiatt 2007, Garman 2011). In the lobes of the pineal gland, pineal influenced by circadian rhythm or solar intensity thebecause pinealocytes pinealocytes are arranged are neurosensory around small cells. lumina The ( capsuleFig.3E (Vigh et al. 1998). Neuropathologists prefer the term pineal body to pineal gland, OneLesions of these of is no vacuolation clinical significance of the cytoplasm can be confused of neurons with in lesionsthe red specificnucleus toof certainthe mesencephalon important diseases ( )of that the could CNS. anddiencephalon, septa of the and pineal it is here gland that are the formed blood vesselsof pia mater penetrate and arachnoid, and are continuations of the leptomeninges of the that neuronal vacuolation is not always synonymousFig.4D of BSE. be mistaken for a lesion of BSE. It should be remembered into the pineal (Vigh et al. 1998). Melanin in the meninges is a non-lesion that can be grossly Spongiform alterations of BSE occur in the neuropil (within observed. Histologically, the melanocytes are flattened cells neuronal processes, especially dendrites) and in the perikaryon with dendritic cytoplasm and filled with granular dark-brown of neurons from specific locations in the brainstem. However, pigment.( ). In These transverse cells can sections, be found melanocytes in the leptomeninges, can be confused or in spongiform alterations affecting the neuropil and neuronal the vessels within the neuropil, adjacent to the leptomeninges bodies are also described in natural and experimental Fig.3F cases of rabies in opossums, foxes (Charlton et al. 1987), withmelanocytes hemosiderin-laden can confuse macrophages. the correct In interpretationimmunohistochemical of the cattle (Foley & Zachary 1995); in ataxic Rottweiler puppies, studiesresults that(Summers utilize diaminobenzidineet al. 1995). (dark) as the chromogen, (Jardimobserved et in al. one 1999), raccoon and (Hamir in goats & Fischerwith progressive 1999). Incidental paresis (Lancasterintracytoplasmic et al. 1987). vacuolation Neuronal of vacuolation neurons in richthe inred lipids nucleus was Lesions of no clinical significance of the mesencephalon is found in 64% of normal adult cattle
Lipofuscin is a yellow-brown granular pigment that (Gavier-Widen et al. 2001), but has been seen even in cattle accumulates in the cytoplasm of neurons in aged), but animals can also and be with only 12 months of age (Hamir et al. 2001). Vacuolation). apparently does not alter the function of the neuron. It generally ofSporadic the neuronal neuronal perikaryon vacuolation in the has habenular been seen nucleus in sheep (Gavier- and deposits in one pole of the perikaryon (Fig.4A Widen et al. 2001) can be seen in 50% of normal cattle (Fig.4E observed in the cytoplasm of glial cells or free in the neuropil. The extracellular occurrence of lipofuscin can be explained goatsSarcocystis (Hooper 1999), horses (Jahns et al. 2006a), and swine, by the process of exocytosis or through rupture of glial cells (Jahns et al. 2006b), generally in neurons of the brainstem. that contained the pigment. This pigment can be engulfed spp. are usually seen distending myofibers). Cattle by macrophages (Jahns et al. 2006a, Wohlsein et al. 2013). of the heart, skeletal muscle, and Purkinje fibers, usually Other age-related alterations include mineralizationcorpora amylacea and without inciting any inflammatory response (Fig.4F hyalinizationin astrocyte processes. of blood Mineralization vessels in the ofbrain blood and vessels meninges in the become infected through ingestion of sporocysts excreted from (Jahnsbrain of et cattle al. 2006a, ( Mandara) affects 2003),predominantly and the vessels of themuscles definitive of the hostintermediate (carnivores, hosts. omnivores), Infection by that Sarcocystis are in turn spp. infectedis common through in cattle ingestion and does of mature not produce cysts (sarcocysts)lesions because in the it Fig.4B localizes within endothelial cells. Rupture of the cysts can cause the dentate nucleus, globus pallidus, internalCorpora capsule, amylacea and caudal nucleus, without any association with generalized hosts for three species of Sarcocysts: S. cruzi, S. hirsuta, and vascular disease (Wohlsein et al. 2013). S.the hominis formation. (Dubey of small et al. granulomas. 1988). Cattle are intermediate arewithin common the cytoplasm in the brains of astrocytes of aging mammals (Hirano 1985,and consist Garman of glucose2011) and polymers should (“polyglucosan be differentiated bodies”); from they Lafora are bodies,located frequently seen in the vestibular, cuneate, and accessory Axonal spheroids can be incidental findings, and are most Borras et al. 1999), but these are seen in within neuronal which can also be an age-related change (Yanai et al. 1994, cuneate nuclei (Jahns et al. 2006a). In dogs, the presence of corpora amylacea axonal spheroids is correlated with age and they are seen in perikaryon and axon (Minassian 2001). Those that are in 50% of dogs more than 12 years of age (Borras et al. 1999). the axons are difficult to differentiate from Finding a few axonal spheroids in the brain also is a common because both appear to be free in the neuropil (Wohlsein et al. incidental finding in sheep and goats, horses, and swine 2013). Sometimes they can be mistaken for fungal organisms, (Hooper 1999, Jahns et al. 2006a,b). Perivascular cuffs can be since they have the same affinity for the special stains used discrete and nonspecific. Inflammation of this type was seen in to highlight these organisms. about 30% of normal adult cattle (Gavier-Widen et al. 2001). Concretions of the pineal gland can occur in humans, The cause of these inflammatory changes is controversial, cattle, horses, sheep, and donkeys, and can vary in size from but the clinical significance is minimal. Pesq. Vet. Bras. 38(11):2099-2108, novembro 2018 2105
Gross and histopathological pitfalls found in the examination of 3,338 cattle brains submitted to the BSE surveillance program in Brazil
A B) Vascular mineralization Fig.4. Incidental findings of the bovine brain. ( ) Lipofuscin is a yellow-orangeC pigment that taccumulates within the perikaryon of neurons in aged animals. In Periodic acid-Schiff (PAS) stain, it appears as PAS-positive granules. PAS, obj.40x. ( D) Multiple vacuolations (siderocalcinosis) at the level of the internal capsule. HE, obj.20x. ( ) PinealE gland concretions or corpora arenacea, brain sand or pineal (acervuli) are multipleF) Quiescent concentric cyst lamellar of Sarcocystis basophilic structures within the pineal gland. HE, obj.40x. ( of the perikaryon of a neuron of the red nucleus in the midbrain. HE, obj.40x. ( ) Neuronal vacuolation of the habenular nucleus in the thalamus. HE, obj.40x. ( sp. in the granular cell layer of the cerebellum. HE, obj.40x. Artifacts due to the methods of slaughter, sampling, and Artifacts related to the collection and manipulation of the fixation of the brain when it is removed from the cranial cavity with a saw, and can brain includes bone particles that lodge within the brain Artifacts due to the method of slaughter, samping, or Cammermeyer neurons ( ) are a partially controversial notmanipulation seen macroscopically. of fresh brain couldLesions be mistakendue to the for method significant of mimic pathologic mineralization (Fig.5B). Dark neurons or antermortem changes. In most cases, these changes are accepted that it is an artifactFig.5C caused by postmortem trauma subject (Cammermeyer 1978). However, it is generally euthanasia can be the cause of death, but often simply mask other alterations that might be a clue as to). whatThese was lesions the underlying disease that led to the animals’ euthanasia. These to the nervous tissue caused by handling it prior to fixation include submeningeal hemorrhages (Fig.5A (Jortner 2006, Wohlsein et al. 2013). This artifact can also should be correctly interpreted as being inflicted on a brain be produced by improper fixation. Dark neurons should not that was normal prior to the decision to kill the bovine. be confused with red neurons, a hallmark neuronal necrosis Pesq. Vet. Bras. 38(11):2099-2108, novembro 2018 2106 Raquel R. Rech et al.
A B Fig.5. Artifacts in the bovine brain. ( ) Leptomeningeal hemorrhage due to the use of a captive bolt to stun cattle before deathC by bleeding. HE, obj.10x. ( ) A focal aggregate of bone sawdust is within the brain parenchyma. This artifact is commonly found at the lateral areas of the cerebrumD when access to the brain is made by open the cranium vault with a handsaw or striker saw. HE, obj.20x. ( ) Dark neurons or Cammermeyer neurons are neurons in the cerebral cortex withE) Postmortem shrunken with artifact. dark basophilic Multiple postmortem cytoplasm and bacilli dark are condensed in the cerebral nuclei. HE, obj.40x. ( ) Freezing artifact. Linear interconnecting clefts crisscross the cerebellar cortex. Those clefts are the resultF) Postmortem of freezing and subsequently thawing of the neural tissue. HE, obj.10x. ( cortex neuropil without inflammatory reaction. Inset: many bacilli obliterate the lumen of a blood vessel. HE, obj.40x. ( artifact. Multiple variable-sized cavities in the brain parenchyma, also called Swiss cheese brain, result from gas bubbles produced by clostridial bacilli. HE, obj.10x.
). (Cantile & Youssef 2016). Linear clefts are made by crystals compared with organs of the abdominal cavity. Autolysis of the Autolysisthat form whenand putrefaction unfixed nervous tissue is frozen (Fig.5D CNS can mimic lesions associated with certain diseases, and deathbe confusing needs to thebe differentiated pathologist. Also, from some ante artefacts mortem observed lesions. when the brain is not immediately fixed in formalin after When the pathologist receives a brain to be examined in the diagnostic laboratory, there is usually little history Autolysis of gray matter can mimic lesions of trauma and brainregarding is relatively the time resistant between to the the death process of the of autolysis, animal and when the autolytic vacuolar changes in myelin can mimic intramyelinic necropsy and subsequent fixation of tissues. As an organ, the edema or Wallerian degeneration. Halos around the perikaryon of neurons, oligodendrocytes, and small vessels are common Pesq. Vet. Bras. 38(11):2099-2108, novembro 2018 2107
Gross and histopathological pitfalls found in the examination of 3,338 cattle brains submitted to the BSE surveillance program in Brazil
Coore R.R., Love S., McKinstry J.L., Weaver H.R., Phillips A., Hillman T., Hiles findings in brains that are autolyzed and should not be confused M.J., Shand A., Helps C.R. & Anil M.H. 2004. Dissemination of brain
Nervoso de Bovinos no Brasil. Valée, Montes Claros. HiranoBaltimore. A. 1985. Neurons, astrocytes and ependyma p.1-91. In: Davis R.L. & is that all? Life Sci. 14(10):1807-1817. Robertson D.M (Eds), Textbook of Neuropathology. Williams and Wilkins, Borison H.L. 1974. Area postrema: chemoreceptor trigger zone for vomiting,
and bone meal. Vet. Rec. 159(5):137-142.
Jardim51(5):449-452. L.L., Andrade-Neto J.P. & Alessi A.C. 1999. Neuronal vacuolation and spongiform lesions in young Rottweiler dogs. Arq. Bras. Med. Vet. Zootec. Vandevelde M., Higgins R.J. & Oevermann A. 2012. General neuropathology,
Pesq. Vet. Bras. 38(11):2099-2108, novembro 2018