Proceedings of the 2010 National Toxicology Program Satellite Symposium

Abstract

The 2010 annual National Toxicology Program (NTP) Satellite Symposium, entitled "Pathology Potpourri," was held in Chicago, Illinois, in advance of the scientific symposium sponsored jointly by the Society of Toxicologic Pathology (STP) and the International Federation of Societies of Toxicologic Pathologists (IFSTP). The goal of the annual NTP Symposium is to present current diagnostic pathology or nomenclature issues to the toxicologic pathology community. This article presents summaries of the speakers' presentations, including diagnostic or nomenclature issues that were presented, along with select images that were used for voting or discussion. Some topics covered during the symposium included a comparison of rat and mouse hepatocholangiocarcinoma, a comparison of cholangiofibrosis and cholangiocarcinoma in rats, a mixed pancreatic neoplasm with acinar and islet cell components, an unusual preputial gland tumor, renal hyaline glomerulopathy in rats and mice, eosinophilic substance in the nasal septum of mice, INHAND nomenclature for proliferative and nonproliferative lesions of the CNS/PNS, retinal gliosis in a rat, fibroadnexal hamartoma in rats, intramural plaque in a mouse, a treatment-related chloracne-like lesion in mice, and an overview of mouse ovarian tumors.

Figure 1

Hepatocholangiocarcinoma (HCCC), a primary hepatic tumor containing both neoplastic hepatocellular and neoplastic biliary epithelial elements. (A) Typical trabecular morphology of hepatocellular carcinoma in conjunction with exuberant neoplastic biliary epithelial proliferation. (B) Neoplastic trabeculae are at least 3 cell layers thick and (C) blend proliferating hepatocytes and biliary epithelial cells in the same cords. Metastases of HCCC in the heart (D) and lung (E) contain both proliferating hepatocytes and biliary epithelial cells. H&E.

Figure 2

Cholangiofibrosis in the rat. (A) A low-magnification image of a liver lobe from a F344/N rat treated with a high dose of furan for several months. A large portion of the lobe has been replaced by cholangiofibrosis with focal areas of regenerative hepatocellular hyperplasia. The overall contour of the lobe has not been appreciably expanded. (B) A different lobe from the same rat as in (A) with a localized contracted area of cholangiofibrosis. The remainder of the lobe is relatively normal. (C) Low-magnification image of a liver lobe from a F344/N rat treated with a high dose of furan for several months. Two protruding nodules of cholangiofibrosis on the surface of the liver consist of markedly dilated, mucus-filled glands. The remainder of the lobe is occupied by resolving sclerotic remnants of cholangiofibrosis. (D) Cholangiofibrosis diffusely distributed in the liver of a Sprague-Dawley rat treated with a high dose of a dioxin-related xenobiotic. Both small and mucus-filled, dilated biliary glands are present. (E) High magnification of 11D showing mucus-filled dilated glands with partial loss of glandular epithelium surrounded by inflammatory cell infiltrates and fibrosis. H&E.

Figure 3

Mixed tumors in the rat. (A) Pancreatic malignant mixed tumor from a male F344/N rat from a 2-year bioassay. (B) Higher magnification of the neoplasm in (A) showing intermingled but distinct acinar cell (AC) and islet cell (IC) components. (C) Extension of neoplastic IC across the fibrous capsule (arrows). (D) Neoplastic IC are pleomorphic and may have mitotic figures (arrow). Ductules (*) are lined by epithelial cells with abundant pale pink cytoplasm and large vesicular nuclei. (E) Pleomorphic neoplastic AC have abundant cytoplasm with decreased zymogen granules and sometimes mitotic figures (arrows). (F) Neoplastic AC are also characterized by large, vesicular nuclei with prominent, often multiple nucleoli (arrows). Ductules (*) are lined by epithelial cells with abundant pale pink cytoplasm and large vesicular nuclei. (G) Preputial gland from a male F344/N rat from a 2-year bioassay. Extensive areas of cartilaginous (C) and fibrous (F) tissues compress and replace the normal glandular architecture. (H) Higher magnification of the mass exhibits cartilage (C) and fibrous connective tissue (F). Dilated ducts (D) are filled with necrotic debris, inflammatory cells, and keratin and lined by poorly differentiated epithelial cells (arrow). (I) Areas of cartilage (C) and fibrous connective tissue (F) in which are scattered acinar-like structures (arrows). Diffuse inflammatory cell infiltrates are present in the fibrous tissue (F). (J) Fibrous connective tissue (F) contains diffuse inflammatory cell infiltrates and surrounds poorly differentiated acinar-like structures (arrow). (K) Fibrous connective tissue (F) contains diffuse inflammatory cell infiltrates and surrounds poorly differentiated acinar-like structures (long arrow). The adjacent dilated duct (D) is distended by necrotic debris, keratin, and inflammatory cells and is lined by poorly differentiated squamous epithelium (short arrows). (L) The poorly differentiated squamous epithelium lining a dilated duct (D) exhibits extension of branching cords and “dropping off” of cell clusters and individual neoplastic cells (arrows) into the underlying fibrous connective tissue (F). H&E.

Figure 3

Mixed tumors in the rat. (A) Pancreatic malignant mixed tumor from a male F344/N rat from a 2-year bioassay. (B) Higher magnification of the neoplasm in (A) showing intermingled but distinct acinar cell (AC) and islet cell (IC) components. (C) Extension of neoplastic IC across the fibrous capsule (arrows). (D) Neoplastic IC are pleomorphic and may have mitotic figures (arrow). Ductules (*) are lined by epithelial cells with abundant pale pink cytoplasm and large vesicular nuclei. (E) Pleomorphic neoplastic AC have abundant cytoplasm with decreased zymogen granules and sometimes mitotic figures (arrows). (F) Neoplastic AC are also characterized by large, vesicular nuclei with prominent, often multiple nucleoli (arrows). Ductules (*) are lined by epithelial cells with abundant pale pink cytoplasm and large vesicular nuclei. (G) Preputial gland from a male F344/N rat from a 2-year bioassay. Extensive areas of cartilaginous (C) and fibrous (F) tissues compress and replace the normal glandular architecture. (H) Higher magnification of the mass exhibits cartilage (C) and fibrous connective tissue (F). Dilated ducts (D) are filled with necrotic debris, inflammatory cells, and keratin and lined by poorly differentiated epithelial cells (arrow). (I) Areas of cartilage (C) and fibrous connective tissue (F) in which are scattered acinar-like structures (arrows). Diffuse inflammatory cell infiltrates are present in the fibrous tissue (F). (J) Fibrous connective tissue (F) contains diffuse inflammatory cell infiltrates and surrounds poorly differentiated acinar-like structures (arrow). (K) Fibrous connective tissue (F) contains diffuse inflammatory cell infiltrates and surrounds poorly differentiated acinar-like structures (long arrow). The adjacent dilated duct (D) is distended by necrotic debris, keratin, and inflammatory cells and is lined by poorly differentiated squamous epithelium (short arrows). (L) The poorly differentiated squamous epithelium lining a dilated duct (D) exhibits extension of branching cords and “dropping off” of cell clusters and individual neoplastic cells (arrows) into the underlying fibrous connective tissue (F). H&E.

Figure 4

Non-amyloid eosinophilic deposits in the kidney of mice and rats. (A) Low and (B) high magnifications of hyaline glomerulopathy from a B6C3F1 mouse treated with pulegone (75 mg/kg by gavage for 2 years). H&E. The renal glomeruli are expanded by amorphous, extracellular, eosinophilic material that effaces the mesangium and capillary loops. (C) The renal lesion from the rat subchronic (90 days) pulegone study is characterized by minimal mesangial thickening and occasional aggregates of eosinophilic globules within glomeruli (arrows). H&E. (D) The mesangium stains blue (indicating collagen fibrils), whereas the aggregates stain magenta (arrow) with Masson's trichrome stain. (E, F) Transmission electron microscopy (TEM) shows the location of these globules within expanded processes of podocytes. (G) TEM of a glomerular capillary loop from a control animal illustrating the uniform thin basement membrane and typical narrow structure of podocyte processes. (H) TEM of a minimally affected kidney from a mouse in the 2-year study reveals electron-dense deposits (arrows) expanding the mesangium, with irregular thickening of the capillary loop basement membrane as well as podocyte fusion and effacement. (I, J) In a glomerulus with marked lesions, the ultrastructural changes included large, well-circumscribed accumulations of closely packed tubules that are non-branching but curvilinear, occasionally forming swirls. (K, L) In the chronic F344/N rat pulegone study, the lesion has a somewhat different TEM morphology; the glomerular tuft is expanded by an amorphous, finely granular, variably electron-dense material with occasional aggregates of small, smooth-margined vacuoles and entrapped cytoplasmic organelles. M–R. Non-amyloid eosinophilic deposits of minimal (M) to mild (N, O) degree within the nasal septum at levels I and II from 2-year-old B6C3F1 mice (Herbert and Leininger 1999). H&E. This lesion is characterized by an amorphous and acellular eosinophilic material within the nasal septum that appears to be associated with the nasal glands and the vomeronasal organ. There is no inflammation or degeneration present. This material stains pale blue with occasional red areas with Masson's trichrome (P) and stains dark magenta by the periodic acid-Schiff (PAS) reaction following prior diastase treatment (Q). A silver stain reveals reticulin fibers and occasional disruption of the glandular basement membrane (R).

Figure 4

Non-amyloid eosinophilic deposits in the kidney of mice and rats. (A) Low and (B) high magnifications of hyaline glomerulopathy from a B6C3F1 mouse treated with pulegone (75 mg/kg by gavage for 2 years). H&E. The renal glomeruli are expanded by amorphous, extracellular, eosinophilic material that effaces the mesangium and capillary loops. (C) The renal lesion from the rat subchronic (90 days) pulegone study is characterized by minimal mesangial thickening and occasional aggregates of eosinophilic globules within glomeruli (arrows). H&E. (D) The mesangium stains blue (indicating collagen fibrils), whereas the aggregates stain magenta (arrow) with Masson's trichrome stain. (E, F) Transmission electron microscopy (TEM) shows the location of these globules within expanded processes of podocytes. (G) TEM of a glomerular capillary loop from a control animal illustrating the uniform thin basement membrane and typical narrow structure of podocyte processes. (H) TEM of a minimally affected kidney from a mouse in the 2-year study reveals electron-dense deposits (arrows) expanding the mesangium, with irregular thickening of the capillary loop basement membrane as well as podocyte fusion and effacement. (I, J) In a glomerulus with marked lesions, the ultrastructural changes included large, well-circumscribed accumulations of closely packed tubules that are non-branching but curvilinear, occasionally forming swirls. (K, L) In the chronic F344/N rat pulegone study, the lesion has a somewhat different TEM morphology; the glomerular tuft is expanded by an amorphous, finely granular, variably electron-dense material with occasional aggregates of small, smooth-margined vacuoles and entrapped cytoplasmic organelles. M–R. Non-amyloid eosinophilic deposits of minimal (M) to mild (N, O) degree within the nasal septum at levels I and II from 2-year-old B6C3F1 mice (Herbert and Leininger 1999). H&E. This lesion is characterized by an amorphous and acellular eosinophilic material within the nasal septum that appears to be associated with the nasal glands and the vomeronasal organ. There is no inflammation or degeneration present. This material stains pale blue with occasional red areas with Masson's trichrome (P) and stains dark magenta by the periodic acid-Schiff (PAS) reaction following prior diastase treatment (Q). A silver stain reveals reticulin fibers and occasional disruption of the glandular basement membrane (R).

Figure 4

Non-amyloid eosinophilic deposits in the kidney of mice and rats. (A) Low and (B) high magnifications of hyaline glomerulopathy from a B6C3F1 mouse treated with pulegone (75 mg/kg by gavage for 2 years). H&E. The renal glomeruli are expanded by amorphous, extracellular, eosinophilic material that effaces the mesangium and capillary loops. (C) The renal lesion from the rat subchronic (90 days) pulegone study is characterized by minimal mesangial thickening and occasional aggregates of eosinophilic globules within glomeruli (arrows). H&E. (D) The mesangium stains blue (indicating collagen fibrils), whereas the aggregates stain magenta (arrow) with Masson's trichrome stain. (E, F) Transmission electron microscopy (TEM) shows the location of these globules within expanded processes of podocytes. (G) TEM of a glomerular capillary loop from a control animal illustrating the uniform thin basement membrane and typical narrow structure of podocyte processes. (H) TEM of a minimally affected kidney from a mouse in the 2-year study reveals electron-dense deposits (arrows) expanding the mesangium, with irregular thickening of the capillary loop basement membrane as well as podocyte fusion and effacement. (I, J) In a glomerulus with marked lesions, the ultrastructural changes included large, well-circumscribed accumulations of closely packed tubules that are non-branching but curvilinear, occasionally forming swirls. (K, L) In the chronic F344/N rat pulegone study, the lesion has a somewhat different TEM morphology; the glomerular tuft is expanded by an amorphous, finely granular, variably electron-dense material with occasional aggregates of small, smooth-margined vacuoles and entrapped cytoplasmic organelles. M–R. Non-amyloid eosinophilic deposits of minimal (M) to mild (N, O) degree within the nasal septum at levels I and II from 2-year-old B6C3F1 mice (Herbert and Leininger 1999). H&E. This lesion is characterized by an amorphous and acellular eosinophilic material within the nasal septum that appears to be associated with the nasal glands and the vomeronasal organ. There is no inflammation or degeneration present. This material stains pale blue with occasional red areas with Masson's trichrome (P) and stains dark magenta by the periodic acid-Schiff (PAS) reaction following prior diastase treatment (Q). A silver stain reveals reticulin fibers and occasional disruption of the glandular basement membrane (R).

Figure 5

(A–F) Malignant ependymoma in a mouse. A series of images presented for voting from a CD-1 mouse in a high-dose group from a 2-year study. The lesion exists as a round cell tumor in proximity to the ventricular system. Differential diagnoses include choroid plexus carcinoma and malignant medulloblastoma. H&E.

Figure 6

Vacuolar lesions in the nervous system of rodents. (A) Intramyelinic edema in the dorsal hippocampus of the brain of a rat treated with triethyltin. Large numbers of vacuoles are present within the dorsal hippocampal commissure, the corpus callosum and the cingula. H&E. (Image is courtesy of Dr. Robert H. Garman, Consultants in Veterinary Pathology, Murrysville, PA.) (B) Compound-induced foamy cytoplasmic vacuolation in the spinal cord ventral horn motor neurons of a rat resulting from phospholipidosis (confirmed using electron microscopy). H&E. (Image is courtesy of Dr. Anna-Lena Berg, Safety Assessment, Pathology, AstraZeneca, S-151 85 Södertaälje, Sweden.) (C) Mucocytes (“Buscaino bodies”) in the optic nerve of a dog. These are a common processing artifact associated with extended immersion in ethanol during paraffin infiltration (typically by over-the-weekend holding on an automated processor) and manifest as pale, blue-gray, amorphous bodies in H&E-stained sections. H&E. They are positive for periodic acid-Schiff (PAS), are birefringent under polarized light, and probably represent degraded myelin. (D) Sciatic nerve injury in a Lewis rat. Axons are disrupted as indicated by digestion chambers (arrow), with multifocal myelin fragmentation. H&E. (E) Luxol fast blue stain of sciatic nerve injury in a Lewis rat. When compared to a contralateral control nerve, there is a marked reduction in staining for myelin sheaths. (F) Labeling to demonstrate ED-1 (a rat macrophage marker) of the same sciatic nerve reveals numerous positive macrophages in demyelinated areas. (Images D, E and F are courtesy of Dr. Karima Kahlat, Department of Physiology and Pharmacology, School of Medical Sciences, University of Bristol, United Kingdom.)

Figure 7

Retinal gliosis in a control F344/N rat. (A) Focally extensive hypercellular lesion (H&E stain) centered within the retina at the optic disc area (arrow). (B) Higher magnification of the lesion showing an expanded optic nerve fiber layer containing cells with elongated nuclei (arrows); fibrillar, eosinophilic cytoplasm; and indistinct cell membranes. (C) Labeling with anti-glial fibrillary acidic protein (GFAP) reveals glial processes (arrows) of reactive Müller cells extending from the outer plexiform layer through the inner nuclear layer and inner plexiform layers abutting the inner limiting membrane. GFAP-stained cells within the optic nerve fiber layer were concluded to be those of traversing Müller cells as well as astrocytes (parallel to the optic nerve fibers), and not the proliferating cells of interest, due to the meager staining immediately adjacent to the nuclei of the cells forming the lesion. (D) Staining with vimentin also clearly identifies glial processes (arrows) of Müller cells and processes within the plexiform, inner nuclear, and optic nerve fiber layers, and inner limiting membrane. Cross-section of the area of interest within the optic nerve fiber layer shows scattered punctate, nonspecific, positive staining with vimentin that was not interpreted to identify the cells of interest.

Figure 8

Fibroadnexal hamartoma in a rat. (A) Low magnification of a skin from a F344/N rat. Note the multinodular presentation with distinct folliculosebaceous units (with centrally located cystic follicular structures bordered by abundant sebaceous epithelium) that are separated by a dense collagenous stroma and do not open to the surface. (B) Higher magnification of (A). Folliculosebaceous units with intraluminal sebaceous secretion, hair shafts (asterisk), and cleft formation (arrowheads). H&E.

Figure 9

“Intramural plaque” in a blood vessel of the mouse lung. (A–C) Lesion from an untreated manganese superoxide dismutase (MnSOD) mouse. Granular, amorphous material with a spindloid cell component is present between the endothelium and the tunica media; a small focus of similar material is present between the tunica media and the tunica adventitia. The asterisk in (A) indicates a pulmonary vein, identifiable by the cardiomyocytes in the vessel wall. H&E.

Figure 10

Chloracne in the mouse. (A) Skin from a control male B6C3F1 mouse in the 2-year NTP study for 3,3',4,4'-tetrachloroazobenzene (TCAB). Hair follicles are normal, and adjacent sebaceous glands can be seen. Black arrows indicate hair follicles; open arrows indicate sebaceous glands. (B) Skin from a male B6C3F1 mouse treated for 2 years with TCAB (30 mg/kg). Note dilation of hair follicles, flattening of the epithelial lining, and atrophy of adjacent sebaceous glands. No infiltration of inflammatory cells can be discerned. This animal was assigned a moderate degree of hair follicle dilation (i.e., six or more follicles segmentally dilated to greater than double the normal diameter within a low-magnification field). Black arrows indicate dilated hair follicles; open arrows indicate atrophic sebaceous glands. (Reprinted from Ramot et al. [2009], with permission from Elsevier.) H&E.

Figure 11

Ovarian proliferative lesions in mice. (A) Normal ovary showing germ cell, stromal, and epithelial elements. (B) Cyst with epithelial hyperplasia. (C) Cystadenoma with adjacent epithelial proliferation. (D) Cystadenocarcinoma. (E) Cystadenoma. (F) Granulosa cell tumor. (G) Sertoli cell tumor. (H) Tubulostromal cell tumor. (I) Bi-ovulate follicle from a RasH2 mouse. H&E.

Figure 11

Ovarian proliferative lesions in mice. (A) Normal ovary showing germ cell, stromal, and epithelial elements. (B) Cyst with epithelial hyperplasia. (C) Cystadenoma with adjacent epithelial proliferation. (D) Cystadenocarcinoma. (E) Cystadenoma. (F) Granulosa cell tumor. (G) Sertoli cell tumor. (H) Tubulostromal cell tumor. (I) Bi-ovulate follicle from a RasH2 mouse. H&E.