Lecture 2 1/31/25 Flashcards
What is a tumor?
a swelling or swollen state
What are some examples of findings that are considered tumors?
-cyst
-abscess
-granuloma
-hyperplasia
What are the characteristics of hyperplasia?
-increase in the number of cells
-increase in cell division
-can only occur in cell types capable of mitosis
How does hyperplasia differ from neoplasia?
-hyperplasia typically subsides if initial stimulus is removed
-stimulus can include inflammation, trauma, hormones, or increased functional demand
-hyperplasia can be diffuse or nodular
What are the characteristics of compensatory hyperplasia?
-done for wound healing
-only needs to get big enough to replace lost tissue
-well-controlled and driven by growth factors
What are the characteristics of idiopathic hyperplasia?
-often age associated
-no functional significance
Which types of hyperplasia are typically nodular?
-compensatory
-idiopathic
Which type of hyperplasia is typically diffuse?
hormone-driven
What are the characteristics of neoplasia?
-new growth
-DNA mutations allow for uncontrolled cell proliferation and tumor formation
-formerly normal cells undergo irreversible genetic changes
-cells become unresponsive to ordinary cell growth controls
What is oncology?
the study of tumors
What is oncogenesis?
process of tumor development, whether benign of malignant
What is carcinogenesis?
processes involved in the development of cancer and/or the malignant transformation of cells
What are the characteristics of benign neoplasms?
-“easily” cured
-do not invade surrounding tissues or spread to new anatomic locations within the body
What is an adenoma?
a benign neoplasm originating from the epithelial cells; endoderm or ectoderm in origin
Which tissues are epithelial?
-skin
-intestines
-lungs
Which tissues are mesenchymal?
-connective tissue
-muscle
-bone
What is a fibroma?
a benign neoplasm originating from the mesenchymal cells; mesoderm in origin
What are the characteristics of malignant neoplasms/cancer?
-not “easily” cured
-have potential to spread/metastasize within tissue, to lymph nodes, or to distant sites
What is a carcinoma?
a malignant neoplasm of the epithelial cells; ectoderm or endoderm in origin
What is a sarcoma?
a malignant neoplasm of the mesenchymal cells; mesoderm in origin
What are the gross features of benign neoplasm?
-localized and/or encapsulated
-“easily” removed
-similar to normal tissue/well differentiated
-slower growth rate with fewer mitotic figures
What are the gross features of malignant neoplasm?
-invasive and infiltrative with possible metastases
-not “easily” removed
-disorganized compared to normal tissue/poorly differentiated
-fast growth rate with more mitotic figures
What are the histologic features of benign neoplasm?
-well-differentiated
-expansive and/or compressive; may have a capsule
-minimal to mild pleomorphism
-minimal to mild nuclear atypia
-low numbers of mitotic figures
-lack a stromal reaction
What are the histologic features of malignant neoplasm?
-poorly or undifferentiated
-invasive and infiltrative with poor demarcations
-moderate to marked pleomorphism
-moderate to marked nuclear atypia with multinucleated or karyomegalic cells
-high numbers of mitotic figures
-scirrhous/desmoplastic response
What is anaplasia/atypia?
loss of cellular differentiation indicative of neoplasia
What is anisocytosis?
variation in cell size within a population of cells
What is ansiokaryosis?
variation in nuclear size within a population of cells
what is carcinoma in situ?
preinvasive epithelial neoplasm that has not yet penetrated the epithelial basement membrane
What is a hamartoma?
mature but disorganized tissue found in its normal anatomic location
What is a desmoplastic /scirrhous response?
-extensive non-neoplastic fibrous connective tissue growth in response to tumor cell factors
-commonly seen with carcinomas
What are the characteristics of malignant tumors and metastasis?
-often a large primary tumor
-multiple smaller masses in the same organ or in different sites/organs are metastases
-malignant tumors do not need metastases to be malignant
How are metastases named?
they keep the same name as the primary tumor but are indicated as metastases in the new tissue in which they are found
What is a teratoma?
-tumor consisting of at least 2 of the 3 primary germ layers
-often originate from the gonads
-typically benign, but size and location can still result in problems
What is lymphoma?
malignant neoplasm of lymphocytes with no benign counterpart
What is mesothelioma?
malignant neoplasm of mesothelial cells with no benign counterpart
What is melanoma?
malignant neoplasm of melanocytes; melanocytoma is benign counterpart
What are the characteristics of mesothelioma?
-arises from cells that line the thoracic and abdominal cavities
-no designation between benign and malignant
-easily spreads throughout body cavity
What are round cell tumors?
a subset of mesenchymal tumors; malignant forms are considered sarcomas
Which tumors are types of round cell tumors?
-lymphoma
-mast cell tumor
-plasma cell tumor
-histiocytoma (benign)
-histiocytic sarcoma (malignant)
-transmissible venereal tumor
What are the characteristics of mast cell tumors?
-mesodermal in origin
-technically do not have a benign counterpart
-cutaneous mast cell tumors can be high or low grade
-characterized by location; cutaneous, subcutaneous, or organ
What are the common sites for plasma cell tumors/plasmacytomas?
-pinnae
-digits
-oral cavity/lips
What are the characteristics of plasma cell tumors?
-high mitotic count
-anisocytosis and anisokaryosis present
-numerous multinucleated cells
-typically benign
-malignant form is called multiple myeloma
What are the characteristics of cutaneous histiocytoma?
-top heavy with a narrow base
-often a dome shaped, smooth, pink, raised mass
-often ulcerated
-commonly found on pinna/head and extremities
-majority occur in dogs younger than 4 years old
-follows typical naming convention; malignant form includes sarcoma in name
-often benign despite high mitotic count
What are the characteristics of transmissible venereal tumor?
-horizontally transmitted infectious tumor of dogs; STI
-usually remains localized but can metastasize
What are the characteristics of brain tumors?
-arise from meninges, neurons, and glial cells
-neuroectodermal in origin
-generally bad; no designation between benign vs. malignant
Why is it important that most tissues have epithelial and mesenchymal components?
most tissues can have both carcinomas and sarcomas that arise
Which type of neoplasm causes an umbilicated/depressed center?
carcinoma
What are the potential consistencies for neoplasms?
-soft
-firm
-hard
What is the typical consistency of lymphoma?
soft
Which consistency is associated with desmoplasia/scirrhous response?
firm
Which consistency is associated with tumors containing bone?
hard
