Lecture # 42 NEOPLASIA - 3 Dr Lecture # 42 NEOPLASIA - 3 Dr. Iram Sohail Assistant Professor Pathology College Of Medicine Majmaah University

OBJECTIVES Explain what is meant by local invasion Explain metastasis

LOCAL INVASION Benign Remains localized at the site of origin Do not infiltrate or invade Slowly expand & mostly develop a fibrous capsule

But some benign lesions do not have capsule, like leiomyoma Examples Adenoma Fibroma But some benign lesions do not have capsule, like leiomyoma

Malignant tumors (cancer) They infiltrate & invade They cause penetration & destruction of surrounding tissue

No capsule Microscopically, crab like feet penetrating the surrounding tissue

So it is necessary for the surgeon to remove the normal surrounding area of tissue along with the actual cancer.

METASTASIS Development of secondary implants, discontinuous with the primary tumor It is the most important property of malignant tumor.

Approximately 30% of newly diagnosed patients present with metastasis. Mostly the larger and more anaplastic primary tumors have more tendencies to metastasize.

Malignant neoplasm spread by 3 pathways Seeding within body cavities Lymphatic spread Hematogenous spread

Seeding within body cavities When a tumor invades a natural body cavity. Examples Ovarian cancers spread through peritoneal cavity.

Brain tumors (medulloblastoma, ependymoma) spread to the meninges through CSF (cerebrospinal fluid).

Lymphatic spread Mostly carcinomas are spread by this route. The lymph nodes & lymphatics involvement is depends upon the location of the tumor.

Examples Carcinoma of lungs spread to the hilar lymph nodes.

Breast cancers are mostly metastasize to axillary lymph nodes. All the metastatic cells eventually reach the thoracic duct through lymphatics.

Sentinel lymph node A sentinel lymph node is the first lymph node in the regional lymphatic system that receives lymph from primary tumor. We can identify this sentinel lymph node by injecting a blue dye.

Surgeons do the biopsy of sentinel lymph node to find out the extent of spread of tumor and the plan the further treatment.

In lymph nodes metastasis, the lymph nodes will be enlarged. But lymph nodes enlargement can also occur in reactive (non – cancerous) conditions.

Hematogenous (blood) spread Mostly sarcomas are spread by this route. Veins are involved more commonly as compare to arteries.

The liver & lungs are the most frequently involved secondary sites in Hematogenous spread.

Mechanism of Metastasis

Common examples of different metastatic tumors Prostatic carcinoma ----spreads to -----bone

Lung carcinoma------spreads to-------brain & adrenal gland