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PA6.1-7 | Neoplasia — Practice Quiz
Practice
14 questions · Untimed · Unlimited attempts
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A 55-year-old man presents with a deeply pigmented, irregular skin lesion on his back. Biopsy shows malignant transformation of melanocytes. Which of the following BEST explains why this tumour is called 'melanoma' rather than 'melanosarcoma'?
A
Melanocytes are derived from neural crest ectoderm, not mesenchyme, so the '-sarcoma' suffix is reserved for mesenchymal tumours
✓
B
Melanoma is a historical misnomer; the correct term should be melanosarcoma
C
Melanomas always behave less aggressively than sarcomas, justifying a different suffix
D
The '-oma' suffix in melanoma indicates it is a benign tumour with low metastatic potential
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A pathologist examines a resected soft-tissue mass from a 40-year-old woman's thigh. Histology shows high nuclear-to-cytoplasmic ratio, prominent nucleoli, frequent atypical mitoses, loss of cellular polarity, and tumour giant cells. These features are collectively described as:
A
Metaplasia
B
Dysplasia
C
Hyperplasia
D
Anaplasia
✓
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Carcinoma of the breast most commonly spreads first to axillary lymph nodes, while osteosarcoma of the femur typically spreads first to the lungs via the bloodstream. Which statement BEST explains this difference in metastatic route?
A
Both carcinomas and sarcomas spread via lymphatics first; the lung involvement in osteosarcoma is a secondary haematogenous event from lymph node seeding
B
Sarcomas spread via lymphatics and carcinomas spread haematogenously because sarcomas have higher E-cadherin expression
C
Carcinomas tend to spread via lymphatics first; sarcomas tend to spread haematogenously first — reflecting the rich lymphatic drainage of epithelial tissues versus the rich vascular supply of mesenchymal tissues
✓
D
Carcinomas preferentially use lymphatic channels because they lack access to blood vessels; sarcomas prefer haematogenous spread because they arise close to large veins
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Which of the following pairings of hallmark of cancer and its molecular mechanism is CORRECT?
A
Enabling replicative immortality — activation of TP53 pathway
B
Inducing angiogenesis — upregulation of thrombospondin-1
C
Sustaining proliferative signalling — inactivation of the RB tumour suppressor gene
D
Evading apoptosis — overexpression of BCL-2 sequestering pro-apoptotic BAX
✓
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In colorectal carcinogenesis, the APC gene is mutated early. APC encodes a protein that normally degrades β-catenin. Loss of APC leads to nuclear β-catenin accumulation and activation of MYC and cyclin D1. APC is classified as:
A
A DNA repair gene whose loss causes microsatellite instability
B
A tumour suppressor gene (TSG) requiring both alleles to be inactivated (Knudson two-hit hypothesis)
✓
C
An oncogene activated by chromosomal translocation, as seen in follicular lymphoma
D
A proto-oncogene that undergoes gain-of-function mutation
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A 45-year-old man from sub-Saharan Africa presents with hepatocellular carcinoma (HCC). He has a history of HBV infection and consumption of improperly stored maize. Which chemical carcinogen is most likely responsible for the additional oncogenic insult, and what does it specifically cause?
A
Nitrosamines formed during grain fermentation, causing methylation of guanine residues
B
Aflatoxin B1 from Aspergillus flavus contamination of stored grains, causing a specific G→T transversion in codon 249 of TP53
✓
C
Aromatic amines from improperly stored grains, causing bladder transitional cell carcinoma
D
Polycyclic aromatic hydrocarbons from mould combustion, causing squamous cell carcinoma of the liver
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During an occupational health audit of a rubber manufacturing plant, workers are found to have 20-fold higher rates of urothelial carcinoma of the bladder. The carcinogen responsible undergoes N-hydroxylation in the liver, is excreted in urine, and then concentrated in the bladder lumen. Which mechanistic step allows this carcinogen to act locally on the urothelium?
A
Aromatic amines act as tumour promoters by stimulating urothelial cell proliferation without DNA damage
B
Aromatic amines bind oestrogen receptors in urothelial cells, mimicking oestrogen-driven proliferation
C
The N-hydroxy metabolite is deacetylated by urothelial enzymes to a reactive electrophile that forms DNA adducts
✓
D
The parent aromatic amine directly alkylates DNA in the bladder without metabolic activation
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A 28-year-old woman with HIV infection presents with cervical intraepithelial neoplasia (CIN 3). Molecular testing shows HPV-16 integration into her genome with loss of E2 expression. Which of the following BEST explains why loss of E2 drives carcinogenesis?
A
E2 loss triggers integration-mediated chromosomal instability by inserting into the BRCA1 locus
B
E2 is a viral oncogene; its loss paradoxically suppresses tumour growth
C
E2 loss activates viral DNA replication, leading to direct cytopathic cell death
D
E2 normally represses E6 and E7 transcription; its loss allows E6 to degrade TP53 and E7 to inactivate RB, removing two critical tumour suppressors
✓
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A 19-year-old male survivor of Hiroshima who received an estimated bone marrow dose of 2 Gy develops acute myeloid leukaemia 8 years later. Which of the following BEST characterises the mechanism by which ionising radiation caused this malignancy?
A
Double-strand DNA breaks cause chromosomal rearrangements (translocations/deletions) that activate proto-oncogenes or inactivate TSGs, with a latency of years to decades
✓
B
Radiation acts as a tumour promoter only; it cannot initiate carcinogenesis without a prior chemical initiating event
C
Ionising radiation directly cleaves oncogene mRNA, generating truncated proteins with constitutive kinase activity
D
Radiation induces retroviral insertion mutagenesis by activating endogenous retroviruses within haematopoietic progenitors
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A 62-year-old woman with known small-cell lung carcinoma (SCLC) develops muscle weakness, hypokalaemic alkalosis, hypertension, central obesity, and hyperglycaemia. Her 24-hour urinary cortisol is 5× the upper limit of normal. ACTH levels are markedly elevated despite a normal pituitary MRI. The MOST likely explanation is:
A
Corticotroph adenoma of the pituitary producing excessive ACTH (Cushing disease)
B
Adrenocortical carcinoma producing autonomous cortisol independent of ACTH
C
Ectopic ACTH secretion by the SCLC causing bilateral adrenal hyperplasia and Cushing syndrome
✓
D
PTHrP secretion by SCLC causing pseudo-Cushing syndrome via parathyroid-hormone-mediated cortisol elevation
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A 55-year-old male smoker presents with new-onset paraesthesiae in his hands and feet, progressive proximal muscle weakness, and a serum calcium of 3.1 mmol/L. Chest CT reveals a 4 cm spiculated mass in the right upper lobe. Which of the following is the MOST likely tumour type and paraneoplastic mechanism?
A
Large-cell neuroendocrine carcinoma secreting calcitonin causing hypercalcaemia
B
Adenocarcinoma of the lung secreting ectopic ADH causing SIADH with paradoxical hypercalcaemia
C
Small-cell lung carcinoma secreting SIADH causing dilutional hypercalcaemia
D
Squamous cell lung carcinoma secreting PTHrP causing humoral hypercalcaemia of malignancy
✓
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A 68-year-old man undergoes a prostatectomy for adenocarcinoma. The pathologist assigns Gleason grade 4+3=7 and reports pT3aN0M0. Which of the following statements CORRECTLY interprets these findings?
A
Gleason grade 4+3=7 reflects the degree of glandular differentiation (histological grade); pT3aN0M0 is the pathological TNM stage (extraprostatic extension, no nodal involvement, no distant metastasis)
✓
B
Grade and stage provide identical prognostic information for prostate cancer; Gleason 7 and pT3a confer the same risk as Gleason 6 and pT2
C
Gleason grade is a staging system; pT3aN0M0 is the histological grading by IHC
D
Grade 7 indicates 7 mitoses per 10 high-power fields; pT3a means three lymph nodes are involved; N0 means no distant metastasis
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A pathologist performs immunohistochemistry (IHC) on a poorly differentiated hepatic metastasis of unknown primary. The tumour cells stain positively for AFP (alpha-fetoprotein) and HepPar-1, and negatively for CK7, CK20, PSA, and TTF-1. Which of the following is the MOST likely primary tumour site?
A
Lung adenocarcinoma
B
Colorectal adenocarcinoma
C
Yolk sac tumour (endodermal sinus tumour) of the testis or ovary
✓
D
Prostate adenocarcinoma
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A 66-year-old woman presents with migratory thrombophlebitis affecting her arm veins, which resolves spontaneously only to recur in a different location two weeks later. She has lost 8 kg over 3 months. CT abdomen-pelvis reveals a 3 cm hypoechoic pancreatic head mass with dilated biliary and pancreatic ducts. Which paraneoplastic syndrome is she exhibiting, and which tumour marker is MOST useful for monitoring her disease?
A
SIADH due to pancreatic adenocarcinoma; CEA is the most useful monitoring marker
B
Trousseau syndrome (migratory thrombophlebitis) due to pancreatic adenocarcinoma; CA 19-9 is the most useful monitoring marker
✓
C
Trousseau syndrome due to hepatocellular carcinoma; AFP is the most useful monitoring marker
D
Eaton-Lambert syndrome due to insulinoma; CA-125 is the most useful monitoring marker
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