The document describes various types of rodent liver lesions including neoplastic lesions such as hepatocellular adenomas and carcinomas, cholangiomas and cholangiocarcinomas, hepatoblastomas, hepatocholangiomas and hepatocholangiocarcinomas, Ito cell tumors, histiocytic sarcomas, hemangiomas and hemangiosarcomas, as well as lymphomas, erythroleukemia, and mononuclear cell leukemia. Photomicrographs are provided to illustrate characteristics such as nodular growth patterns, cellular pleomorphism, and infiltrative properties of these rodent liver tumors and cancers.

1. Rodent Liver Lesions - Neoplastic
R. R. Maronpot
maronpot@me.com
Photomicrographs courtesy of the National Toxicology Program (http://ntp.niehs.nih.gov)

2. Hepatocellular adenoma
• Nodular and compressing
• Oblique impingement on surrounding
parenchyma
• Loss of lobular structure
• Difference in cell size and/or tinctorial staining
• Occasional trapped portal triads

5. Hepatocellular tumor

6. Hepatocellular Adenoma

8. Hepatocellular Adenoma

11. Hepatocellular Adenoma

14. Hepatocellular carcinoma
• Locally infiltrative
• Cellular pleomorphism
• Loss of normal lobular structure
• Increased mitosis, necrosis, and/or
hemorrhage may be present
• Altered tinctorial staining
• Variable growth patterns
– Trabecular, acinar, solid, other

15. Hepatocellular tumor

17. Hepatocellular Carcinoma

19. Hepatocellular Carcinoma

20. Hepatocellular Carcinoma

21. Hepatocellular Carcinoma

22. Hepatocellular Carcinoma

23. Hepatocellular Carcinoma

24. Hepatocellular carcinoma

31. Carcinoma arising in Adenoma

32. Carcinoma Arising in Adenoma

35. Hepatoblastoma
• Discrete nodular growth with variable
structure, often within hepatocellular
adenoma or carcinoma
• Cells often small, strongly basophilic, and may
be elongated
• Cells arranged radially, concentrically, as
rosettes, trabeculae and/or pseudoglands
• Vascular cavities
• Osteoid differentiation may be present

39. Hepatoblastoma arising in adenoma

41. Hepatoblastoma with Osseous
Metaplasia

43. Cholangioma
• Variable size and shape glandular acini
• Expansive and compressive growth
• Cells mostly in a single layer without
surrounding stroma
• Cells reasonably well differentiated with
slightly basophilic cytoplasm
• Simple and cytic forms
• Occasional trapped hepatocytes

44. Cholangioma

45. Cholangioma

47. Cystic Cholangioma – Benign Bile Duct
Tumor

49. Glandular structures lined
by a single layer of cuboidal
to columnar epithelium

50. Cystic Cholangioma

54. Cholangiocarcinoma
• Locally invasive glandular, solid and/or
papillary growth pattern
• Cells are single or multiloayers with large
nuclei and basophilic cytoplasm
• May be associated with some fibrosis
• A controversial version with intestinal
metaplasia, extensive fibrosis, dilated mucus-
and debris-filled glands, and inflammation is
currently being debated

56. Cholangiocarcinoma

61. Cholangiocarcinoma

62. Well Differentiated Cholangiocarcinoma

64. Well-Differentiate Cholangiocarcinoma

65. Hepatocholangiocellular adenoma
• Combines merged features of hepatocellular
cords and single layered biliary ductules
• Hepatocytes may form ductules that resemble
biliary cells

66. Hepatocholangioma

67. Hepatocholangioma

68. Hepatocholangioma

69. Hepatocholangiocellular carcinoma
• Features of hepatocellular carcinoma and/or
cholangiocarcinoma
• Cellular stratification and atypia of biliary
component
• Increased mitoses may be present

70. Hepatocholangiocarcinoma

71. Hepatocholangiocarcinoma

72. Hepatocholangiocarcinoma

73. Hepatocholangiocarcinoma

74. Hepatocholangiocellular carcinoma

77. Hepatocholangiocellular Carcinoma

78. Hepatocholangiocellular Carcinoma

79. Hepatocholangiocellular Carcinoma

80. Hepatocholangiocellular Carcinoma

81. Hepatocholangiocellular Carcinoma

82. Hepatocholangiocellular Carcinoma

83. Ito cell tumor
• Focal to diffuse single or multicentric sheets
and/or clusters of variably sized and shaped
cells
• Tumor cells often vacuolated and present
along hepatocyte cords
• Unencapsulated growth that replaces normal
hepatic parenchyma
• Spindle-shaped cells may be part of growth

84. Ito Cell Hyperplasia Ito Cell Tumor

85. Ito Cell Hyperplasia

88. Ito Cell Tumor

89. Ito Cell Tumor

90. Ito Cell Tumor

91. Ito Cell Tumor

94. Ito Cell “Tumor”

96. Ito Cell Tumor in a Rat

97. Ito Cell Tumor in a Rat

99. Histiocytic sarcoma
• Single or multicentric nodules composed of
uniform population of round to oval cells with
foamy cytoplasm
• Growth along sinusoids and vascular
structures
• Multinucleated giant cells may be present
• Mitoses may be numerous

100. Histiocytic Sarcoma

103. Histiocytic Sarcoma

105. Histiocytic Sarcoma

109. Histiocytic Sarcoma

111. Histiocytic Sarcoma

112. Histiocytic Sarcoma

113. Histiocytic Sarcoma

114. Hemangioma
• Blood-filled spaces lined by a single layer of
uniform endothelial cells without atypia
• Occasional solid areas of uniform endothelial
cells without atypia may be present
• May be multifocal and associated with
angiectasis
• Capillary and cavernous growth patterns are
seen

115. Hemangioma

119. Hemangioma

122. Hemangioma

123. Hemangioma

125. Hemangiosarcoma
• Pleomorphic multilayered and/or clustered
pleomorphic endothelial cells
• Various poorly formed and infiltrative vascular
growth patterns
• Undifferentiated areas and mitotic figures
often present

126. Hemangiosarcoma

129. Hemangiosarcoma

132. Hemangiosarcoma

137. Hemangiosarcoma

139. Hemangiosarcoma

141. Lymphoma in a Tg Mouse

142. Lymphoma in a Tg.AC Mouse

143. Erythroleukemia in a Control Tg.AC
Mouse

144. Erythroleukemia in a Control Tg.AC
Mouse

145. Erythroleukemia in a TgAC Mouse

146. Erythroleukemia in a TgAC Mouse

147. Mononuclear Cell Leukemia

148. Mononuclear Cell Leukemia