24 Questions
What is the most common site of metastasis in carcinomas of thyroid, breast, lung, prostate, and kidney?
Bones
Which of the following effects is NOT associated with bone metastases?
Increased bone density
What is the term for the spread of malignant cells through body cavities, such as the peritoneal or pleural cavity?
Transcoelomic spread
Which type of spread is associated with bilateral ovarian metastases in females?
Transcoelomic spread
What is the microscopic appearance of metastases?
Resemble the primary tumor
Which of the following organs is an uncommon site for metastases?
Muscles
What is the term for the spread of malignant cells through the blood stream?
Hematogenous spread
What is the type of spread responsible for the formation of metastatic peritoneal/omental nodules accompanied by hemorrhagic ascites?
Transcoelomic spread
What is the primary mechanism of distant spread in carcinomas?
Lymphatic spread
What is the result of lymph node capsule infiltration during lymphatic spread?
The nodes become fixed
What is the fate of most tumor emboli in the circulation?
They are destroyed by immune mechanisms
What is the mechanism of direct spread in malignant tumors?
Invasion of ECM
What is the result of tumor cells spreading to a surface such as skin or mucosa?
Ulceration
What is the route of spread of tumor cells from one hollow organ to another adjacent one?
Direct spread
Which of the following is a characteristic of lymphatic permeation?
Growing inside the lumen of lymphatics as solid columns
What is the term for the spread of tumor cells from one node to another through efferent lymphatics?
Lymphatic spread
Which type of tumor is more likely to reach the circulation by direct invasion of blood vessels within the tumor?
Sarcoma
What is the term for the final stage of tumor metastasis, where tumor cells settle in a new site and proliferate?
Metastatic deposits
What is the usual route for malignant cells to reach the venous circulation in case of carcinoma?
Through the thoracic duct after lymphatic spread
Which of the following organs is NOT a common site for metastases from tumors of organs drained by the systemic veins?
Liver
Which route is responsible for metastases in brain, spinal cord, and vertebrae without causing lung metastases?
Through the vertebral system of veins
What is the characteristic of the blood vessels formed in tumors due to the release of tumor-derived angiogenesis factor?
They are more numerous and thin-walled in case of sarcomas
Which of the following statements is TRUE about tumor metastases?
Tumor metastases can occur through both lymphatic and hematogenous spread
Which of the following is a common site for metastases from tumors of the pelvic organs?
Vertebrae
Study Notes
Metastasis and Spread of Cancer
- Metastases can occur in various organs, with the most common sites being the liver, lungs, bones, and brain.
Hematogenous (Blood) Spread
- Metastases can appear as scattered round nodules of variable sizes.
- Bone metastasis is common in carcinomas of the thyroid, breast, lung, prostate, and kidney, and develops in vascular bone sites.
- Bone metastases are commonly osteolytic, but can be osteosclerotic in cases of prostate cancer.
Effects of Bone Metastases
- Pathological fracture
- Severe pain
- Bone marrow destruction leading to pancytopenia (significant reduction in the number of almost all blood cells)
Spread Through Body Cavities (Transcoelomic Spread)
- Trans-peritoneal spread can occur from carcinomas of the stomach, colon, and pancreas, leading to metastatic peritoneal/omental nodules accompanied by hemorrhagic ascites.
- Krukenberg tumors can occur in females, where carcinoma of the stomach (or colon) is associated with bilateral ovarian metastases.
Other Methods of Spread
- Transluminal implantation: malignant cells can detach from transitional carcinoma of the renal pelvis and become implanted in the mucosa of the urinary bladder.
- Lymphatic permeation: malignant cells can grow inside the lumen of lymphatics, causing marked lymphatic obstruction and lymphatic edema.
Pattern of Blood Spread
- Malignant cells can reach the venous circulation through the thoracic duct (after lymphatic spread) or by direct invasion of blood vessels within the tumor.
- Tumors are richly vascularized due to the release of tumor-derived angiogenesis factor, leading to the formation of feeding vessels derived from the host.
Course of Tumor Emboli
- Emboli derived from primary tumors of organs drained by systemic veins can cause lung metastases.
- Emboli derived from tumors of the lungs (whether primary or metastatic) can cause metastases in different organs such as the liver, bones, etc.
- Emboli derived from tumors of organs drained by the portal vein can cause liver metastases.
Degradation
- Proteolytic enzymes, such as IV collagenase and cathepsin D, can degrade basement membrane and connective tissue, allowing for invasion.
Migration
- Tumor-derived cytokines (mobility factors) can mediate migration of tumor cells.
Vascular Dissemination and Homing of Tumor Cells
- Tumor cells can cross the vascular basement membrane and adhere to platelets, which affords them some protection from host immune cells.
- The surviving tumor cell emboli can get impacted in small vessels, leading to adherence to the endothelium, crossing the basement membrane, and finally settling in the new site (homing), where they can proliferate and form metastatic deposits.
Routes of Spread
- Local (Direct) Spread: Malignant cells can spread in all directions along lines of least resistance, with some structures like cartilage, periosteum, and elastic tissue delaying direct spread.
- Distant Spread (Metastasis): Occurs through lymphatic or hematogenous spread, with lymphatic spread occurring more commonly with carcinomas than sarcomas.
This quiz covers the pathology of organ metastases, including the most common sites of metastases, gross and microscopic pictures, and specific types of metastases such as bone metastasis.
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