Pathology Cheat Sheet
The Host Feels the Tumour
Tumour host effects for NEET-PG: cachexia, PTHrP hypercalcaemia, SIADH, ectopic ACTH, Lambert-Eaton, acanthosis nigricans, immunoediting, and tumour markers.
MedNext Academy | 3 min read
The Host Feels the Tumour
Tumour host effects for NEET-PG: cachexia, PTHrP hypercalcaemia, SIADH, ectopic ACTH, Lambert-Eaton, acanthosis nigricans, immunoediting, and tumour markers.
The effects of tumours on the host including paraneoplastic syndromes, and the immune response to cancer.
High-yield lines
- Tumours harm the host through local mass effects, systemic wasting, and paraneoplastic syndromes.
- Cancer cachexia preferentially loses skeletal muscle and is driven by cytokines such as TNF-alpha, so it cannot be reversed by nutrition alone.
- Hypercalcaemia of malignancy is most commonly caused by PTHrP secreted by squamous cell carcinoma of the lung.
- The syndrome of inappropriate ADH secretion is classically caused by small cell lung carcinoma.
- Ectopic ACTH secretion causing Cushing syndrome is most often due to small cell lung carcinoma, bronchial carcinoid, and medullary thyroid carcinoma.
- Lambert-Eaton myasthenic syndrome results from antibodies to presynaptic voltage-gated calcium channels and improves with repeated exercise, unlike myasthenia gravis.
- Acanthosis nigricans of sudden onset in an adult suggests an internal malignancy, most classically gastric carcinoma.
- Cancer immunoediting proceeds through elimination, equilibrium, and escape phases.
- Tumour antigens include oncofetal antigens such as AFP and CEA and overexpressed proteins such as HER2.
- Cytotoxic T lymphocytes and natural killer cells are the main effectors of anti-tumour immunity.
- Immunosuppressed patients have a higher incidence of certain cancers, supporting the concept of immune surveillance.
- AFP is a marker of hepatocellular carcinoma and yolk sac tumour, and CA-125 is a marker of ovarian carcinoma.
Mapped competency codes
- PA7.4
- PA7.5
Continue into the full chapter
This summary maps to PA7-neoplastic-disorders.
Frequently Asked Questions
Which tumour classically causes SIADH?
Small cell lung carcinoma, which secretes ectopic antidiuretic hormone leading to water retention and dilutional hyponatraemia.
What causes hypercalcaemia of malignancy?
Most commonly parathyroid hormone-related protein secreted by squamous cell carcinoma of the lung, which acts on the PTH receptor to raise calcium.
How does Lambert-Eaton syndrome differ from myasthenia gravis?
Lambert-Eaton syndrome is caused by antibodies to presynaptic calcium channels and improves with repeated exercise, whereas myasthenia gravis worsens with exercise and prominently affects ocular muscles.
What are the three phases of cancer immunoediting?
Elimination, in which the immune system destroys nascent tumour cells; equilibrium, a balance phase; and escape, in which the tumour evades immune control and becomes clinically evident.
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