Major types of Carcinoma Flashcards
Understand the pathologic features that distinguish a benign and malignant tumor.
Benign tumors do not invade or metastasize. They tend to grow slowly, over the course of years. These tumors are often encapsulated, meaning they are surrounded by a thin layer of connective tissue that separates the tumor from the surrounding tissue. Cells of these tumors tend to be uniform in appearance and less differentiated than normal epithelial cells, but still recognizable as epithelial cells of the original tissue. Benign tumors can still cause damage via compression or producing harmful proteins.
Malignant tumors invade the surrounding tissues and can then metastasize
Understand what histological feature defines “invasion”.
Invasion by a tumor indicates that along the edge of the carcinoma tumor cells have broken through the basement membrane that separates the epithelium from the underlying connective tissue.
Understand the distinction between stage and grade, and the principles of the TNM grading system.
Stage is the extent to which a tumor has spread (at the time of diagnosis). The staging of tumors is often done by TMN classification. T stands for size of the tumor, with Tis meaning tumor in situ (still confined within the epithelium), and T1-4 indicating increasing size and involvement as number increases. N stands for lymph node involvement. No indicates no involved nodes, with increasing involvement on a scale of 1 to 4. M is for metastasis, Mo is no metastasis and M1 indicates distant metastasis.
Grade is the state of differentiation of the tumor cells in histological sections. Low grade indicate the cells are well
differentiated and exhibit feature of the normal epithelium. High grade tumors do not resemble normal epithelial cells. These cells are more likely to be pleomorphic, anaplastic, have a high nuclear:cytoplasm ratio, show unusual mitotic figures and have a high mitotic rate.
Know the risk factors for major types of lung cancer.
In general, about 85%-90% of lung cancers are caused by long term cigarette smoking (exposure measured in pack-years).
Family history is also a critical factor. Other risk factors include age, occupational hazards such as exposure to metal vapors or asbestos, exposure to air pollutants particularly radon gas and previous history of lung cancer.
Squamous Cell Carcinoma: strongly linked to smoking
Adenocarcinoma: many cases linked to smoking, also most common lung cancer in non-smokers
Bronchioalveolar carcinoma: not linked to smoking
Large Cell Cancer: not specified
Small Cell Cancer: strongly linked to smoking
Pathologic features: Squamous Cell Carcinoma:
● Arise in areas of sqaumous metaplasia
● Occurs in major branches of bronchial tree (ie centrally)
● Often large
● Often exhibit central area of necrosis
● Moderately well differentiated; cells appear squamous with keratin and keratin pearls present
● P53 mutations, loss of Rb, inactivation of p16 are common
● Can produce parathyroid related protein leading to hypercalcema
Pathologic features: Adenocarcinoma:
● Arise centrally or in periphery (in areas of scarring)
● Cells form primitive glands and secrete mucin
● K-Ras mutations common
● Subclass = bronchioalveolar carcinoma
○ Cells grow along alveolar septae, along airspace structures
○ Very little stroma produced by tumor
Pathologic features: Large Cell Carcinoma:
● Undifferentiated, High grade cancer
● Anaplastic cells produce neither keratin or mucin
● Highly pleomorphic
● Produce large, bizarre appearing nuclei
● Bizarre mitotic figures
Pathologic features: Small Cell Carcinoma:
● Can arise anywhere in lung
● High grade, poorly differentiated
● Small, dark straining clusters of cells
● Stain positive for neruoendocrine markers
● Highly aggressive and metastasizes widely, especially to brain
pancreatic carcinoma: pathologic features:
Pathologic Features:
● Moderately differentiated adenocarcinoma (produce mucin)
● Usually arise in ducts (not acini)
● K-Ras mutations very common, also loss of p16, SMAD4 and p53
● Patients present with late stage disease
● Tumors synthesize a lot of connective tissue stroma – tumors feel very hard
● Infiltrate entire gland
● Commonly metastasizes to liver, abdominal lymph nodes and celiac plexus of nerves
Pancreatic carcinoma: risk factors
Risk Factors: ● Mostly unknown… ● Age ● Family history ● Smoking ● Alcoholism (chronic pancreatitis) ● Diabetes mellitus ● Peutz-Jeghers/BRCA2
Pancreatic carcinoma: prognosis
Prognosis: Is abysmal. Five year survival is <5% because cancer grows silently, without causing symptoms or signs until the
tumor is large and has metastasized
Pancreatic carcinoma: treatment options.
Treatment:
● Small lesions discovered early can be surgically resected (not common)
● Radiation, alone or with chemotherapy
● Surgery can include removal of most of the pancreas, common bile duct, gall bladder and duodenum (Whipple
Procedure)
Colorectal carcinoma: pathological features
Pathological Features:
● Moderately well differentiated adenocarcinomas
● Usually arise in pre-existing adenmatous polyps (two major types)
○ Tubular Adenoma – tethered to mucosa by stalk
○ Villus Adenoma – long, finger-like projections with heads that look like cauliflower (more common to rectum)
○ As polyps increase in size, more likely to become cancerous
● Usually invades up through submucousa, muscularis propria and enters blood or lymphatics
● Lung and liver are common sites of metastasis
● Left-sided lesions usually appear apple-core like
● Right-sided neoplasms produce a polypoid mass that protrudes into the lumen
Colorectal carcinoma: clinical features
Clinical Features:
● Left (descending colon): constipation, change in stool caliber and colon obstruction
● Right (ascending): Cancers can grow to large sizes before symptoms develop because the fecal stream is liquid on
the right. When symptoms present, they may be abdominal pain, blood or mucous in the stool or anemia (from
colonic bleeding).
Colorectal carcinoma: risk factors
Risk Factors: ● Age ● Family history ● Alcohol consumption ● Diet rich in animal meat and fat ● Obesity
