QUESTION 74
A pathologist is examining a surgically removed mass under the microscope. Of the following, which feature would indicate the mass was malignant?
A. Necrosis
B. A high mitotic rate
C. Nuclear pleomorphism
D. Focal calcification
E. Invasion of surrounding tissue.
Answer for Question 74
Answer: E (invasion of surrounding tissue)
Explanation: although necrosis, a high mitotic rate, and nuclear pleomorphism are commonly found in malignant neoplasms, they can also occasionally be identified in some benign tumors as well, and, as such, are not an absolute marker of malignancy (e.g., nodular fasciitis has a high mitotic rate and nuclear pleomorphism, and can be misdiagnosed as a sarcoma, but, is in fact a benign proliferation). Focal calcification, in areas of necrosis or areas of scarring can also occur in both tumor types. The two characteristic features that distinguish malignant tumors from benign tumors are the ability of malignant tumors to invade surrounding tissue and to metastasize to distant sites; and, of these two, the only one possessed by all malignant tumors is the ability to invade. Basal cell carcinoma of the skin, a malignant tumor, is locally invasive, but rarely metastasizes, and malignant neoplasms of the brain rarely metastasize. Drop metastases associated with a medulloblastoma are not technically metastatic.
QUESTION 75
Prior to an elective laparoscopic cholecystectomy, a 54-year-old male has a chest x-ray as part of his pre-operative work-up. The x-ray reveals a mass in the left lung, which is subsequently surgically excised. The pathologist examining the tissue notes it to be well-circumscribed, firm, and gray-white. Microscopically, he sees disorganizing but otherwise benign-appearing hyaline cartilage. Of the following, what is the best term to describe this mass?
A. Adenoma
B. Chondrosarcoma
C. Hamartoma
D. Choristoma
E. Hyalinoma
Answer for Question 75
Answer: C (hamartoma)
Explanation: a disorganized collection of otherwise normal appearing tissue in an area where that tissue normally occurs is referred to as a hamartoma (cartilage is a normal component of the bronchi). A collection of benign appearing and normally developed cells at an abnormal location (e.g., a nest of adrenal gland cells in the cortex of the kidney), is termed a choristoma. An adenoma is a benign tumor derived from epithelial cells and a chondrosarcoma would be a malignant tumor derived from cartilage. The mass has no features of malignancy.
QUESTION 76
A pathologist is examining a repeat cervical biopsy from a 25-year-old female with a history of multiple sexual partners. She is positive for HPV16. Previous biopsies have revealed mild to moderate dysplasia. Of the following, which microscopic finding would indicate that carcinoma has developed within the dysplastic epithelium?
A. Marked disorganization of cellular maturation from basal to apical layers
B. Numerous mitotic figures throughout the epithelium
C. Hyperchromatic nuclei of various sizes throughout the epithelium
D. Sloughed outer layer of the epithelium
E. Nests of atypical epithelial cells within the superficial dermis
Answer for Question 76
Answer: E (nests of atypical epithelial cells within the superficial dermis)
Explanation: nests of atypical epithelial cells within the superficial dermis would indicate invasion, which is a feature of carcinoma. A-C above, as they are confined to the epithelium are features of dysplasia and would not be indicative, by themself, of carcinoma.
QUESTION 77
A 23-year-old male develops abdominal pain. A CT scan reveals a mass in the liver. A surgical resection is performed. Microscopic examination of the mass by the pathologist reveals a diagnosis of metastatic osteosarcoma. Subsequently, radiologic examination of the right knee reveals a mass. Of the following, which route most likely allowed the neoplasm to spread from the knee to the liver?
A. Spread of tumor cells through the lymphatics
B. Spread of tumor cells through the blood
C. Spread of tumor cells along the surface of nerves
D. Invasion and growth along the lymphatics
E. Invasion and growth along the blood vessels
Answer for Question 77
Answer: B (spread of tumor cells through the blood).
Explanation: While it is not absolute, sarcomas are most known for hematogenous spread. The tumor cells enter the blood vessels and are carried by the blood to distant sites where they implant and grow. Carcinomas are more commonly known for lymphatic spread. While tumors can grow along nerves, distant spread by growing along a nerve would not be a metastasis. Renal cell carcinoma and hepatocellular carcinoma are known for invading into and then growing along blood vessels, but spreading in this manner would not technically be a metastasis, since there is communication with the original tumor site.
QUESTION 78
A neuropathologist is examining a biopsy of a brain tumor at frozen section. Features consistent with a glioblastoma are identified. Molecular analysis of the tumor reveals over-expression of the PDGF gene. This molecular abnormality contributed to which of the following mechanisms by which this tumor developed?
A. Evasion of immune surveillance
B. Sustained angiogenesis
C. Evasion of apoptosis
D. Self-sufficiency for growth signals
E. Insensitivity to growth-inhibitory signals
Answer for Question 78
Answer: D (self-sufficiency in growth signals)
Explanation: PDGF is platelet derived growth factor. In patients with glioblastoma, over-expression of the PDGF gene can occur, resulting in abnormal stimulation of the growth and division of the cell. The cells can grow and divide outside of the normal chain of events and therefore, have developed a self-sufficiency in their growth signals.
QUESTION 79
A young woman is diagnosed with breast cancer after a biopsy of a suspicious mass that had been detected by mammography. The pathologist confirmed the diagnosis of invasive ductal carcinoma and molecular analysis revealed that the tumor was HER2 positive. She received chemotherapy, including anti-HER2 antibodies. Her molecular abnormality contributed to which of the following mechanisms by which this tumor developed?
A. Evasion of immune surveillance
B. Sustained angiogenesis
C. Evasion of apoptosis
D. Self-sufficiency for growth signals
E. Insensitivity to growth-inhibitory signals
Answer for Question 79
Answer: D (self-sufficiency in growth signals)
Explanation: HER2 (also referred to as ERBB2) is a member of the epidermal growth factor receptor family. A mutation in this receptor allowed the patient’s cells to be very sensitive to growth factors, and hence, the development of carcinoma occurred as there was uncontrolled cell growth. When the growth factor receptor is mutated and as a result more responsive to growth factor stimulation, the neoplastic cell has developed self-sufficiency for growth signals.
QUESTION 80
A large medical center that conducts molecular analyses of neoplasms for various small hospitals in the area, specializing in no specific tumor type, conducts a statistical analysis of their last 1000 tumors. Of the following, a mutation of which gene did they see most commonly?
A. ABL
B. MYC
C. ERBB1
D. RAS
E. PTEN
Answer for Question 80
Answer: D (RAS)
Explanation: 30% of all tumors have a mutated RAS, and it is the most commonly identified mutation in human tumors in general. If the medical center had specialized in a specific tumor type, RAS may not have been the most commonly identified oncogene.
QUESTION 81
A 53-year-old male with a 45 pack-year smoking history is diagnosed with pancreatic adenocarcinoma during the work-up of prolonged and unexplained abdominal pain. Molecular analysis of the tumor reveals a mutated RAS gene. Of the following, what was the most likely mechanism by which this mutation contributed to the development of the tumor?
A. Pre-mature hydrolysis of ATP
B. Impaired hydrolysis of ATP
C. Pre-mature hydrolysis of GTP
D. Impaired hydrolysis of GTP
Answer for Question 81
Answer: D (impaired hydrolysis of GTP)
Explanation: mutation of the RAS gene is commonly identified in a pancreatic adenocarcinomas. RAS is a signal transducing protein, a link between the growth factor receptor and the cascade of proteins (PI3K to AKT to mTOR or RAF to MAPK) that lead to activation of transcription factors in the nucleus. When RAS has GTP bound, it is active,and hydrolysis of the GTP inactivates RAS. So, impaired hydrolysis of the GTP would lead to prolonged activation of RAS and abnormal stimulus of nuclear transcription.
QUESTION 82
A pathologist is examining a tumor removed from the left testis of a young boy. Within the tumor, the pathologist identifies squamous epithelium overlying sebaceous glands, hyaline cartilage, neural tissue, and hepatocytes. Of the following, what is the correct name for this tumor?
A. Hamartoma
B. Carcinoma
C. Sarcoma
D. Teratoma
E. Choristoma
Answer for Question 82
Answer: D (teratoma)
Explanation: teratomas, a form of germ cell tumor, have components derived from all three germ cell layers (ectoderm, mesoderm, and endoderm). The skin is derived from ectoderm, the neural tissue is derived from endoderm, and the hyaline cartilage is derived from mesoderm.
QUESTION 83
A pathologist is examining a malignant neoplasm of the lung. Molecular analysis reveals that the tumor has a mutation of the RB gene. Of which of the following mechanisms did the mutation present contribute to the development of the neoplasm?
A. Self-sufficiency in growth signals
B. Insensitivity to growth-inhibitory signals
C. Altered cellular metabolism
D. Evasion of apoptosis
E. Limitless replicative potential
Answer for Question 83
Answer: B (insensitivity to growth inhibitory signals)
Explanation: RB is a tumor suppressor gene. Although it has other functions, when it is hypophosphorylated, the RB protein binds to E2F, which inhibits the transition from G1 to S. When hyperphosphorylation of RB occurs, through actions of Cyclin D/CDK4 and others, E2F is released and transcription occurs. Therefore, RB is growth inhibitory, and mutations to the RB gene will result in an insensitivity to growth inhibitory signals.
QUESTION 84
A researcher is studying the role of apoptosis in breast tissue following a period of lactation after the birth of a child. In their study, they wish to promote apoptosis in samples of lactating breast tissue to study its effects. Promotion of transcription of which of the following genes would best bring about their desired effects?
A. RB
B. Cyclin D
C. MYC
D. TP53
E. GADD45
Answer for Question 84
Answer: D (TP53)
Explanation: the role of TP53 is to identify DNA damage, arrest the cell cycle at G1, trigger repair of the damaged DNA, and if repair is not possible, caused senescence or apoptosis of the cell. Of the genes listed, TP53 is the only one that plays a significant role in the promotion of apoptosis. GADD45 is a DNA repair gene. RB and Cyclin D control the transition from G1 to S.
QUESTION 85
A research oncologist is studying the Warburg effect in neoplastic cells obtained from an individual with small cell carcinoma of the lung. Given that the Warburg effect is present in this cell population, the breakdown of glucose to which of the following substances is expected to be greater than expected?
A. Lactose
B. Water and oxygen
C. Glycine
D. Reactive oxygen species
E. Triglycerides
Answer for Question 85
Answer: A (lactose)
Explanation: in the Warburg effect, neoplastic cells preferentially breakdown glucose to lactose, even in the presence of sufficient oxygen (aerobic glycolysis). While this is an inefficient way to produce ATP, it is a good way to produce other substances required for growth (including proteins, lipids, and nucleic acids). Oxidative phosphorylation efficiently reduces glucose to water and oxygen, producing the maximum amount of ATP, but does not generate substances necessary for cellular growth. Other rapidly growing cells (e.g., during fetal develop) can also exhibit the Warburg effect, so it is not specific to cancer.