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Epidemiology: Pathology Basis of Caner Lec-14 Lecturer: Dr. Twana A. Mustafa What is the difference between “tumor” vs “cancer” Tumor – Either benign or malignant Cancer – Usually malignant CANCER HISTOLOGICAL TYPE • Three Major Categories: – Epithelial – “Carcinoma” – Mesenchyme – “Sarcoma” – Hematopoitic – “Leukemia/Lymphoma” • Other Minor Categories: – Nevocytic – “Melanoma” – Germ cell – Teratoma, Seminoma, Yolk sac tumor, Choriocarcinoma, etc… – Endocrine/Neuro – Carcinoid/Insulinoma/small cell carcinoma, etc… CARCINOMA • Squamous – Squamous Cell Carcinoma. • Glandular - Adenocarcinoma. • Transitional – Transitional Cell Carcinoma. • Small cell – Small cell carcinoma SARCOMA • Muscle – Smooth muscle: Leiomyosarcoma – Skeletal muscle: Rhabdomyosarcoma • Fat – Liposarcoma • Skeleton – Osteosarcoma • Cartilage – Chondrosarcoma Carcinoma • Carcinoma (Cancer of the epithelium) 85% Epithelium is the term applied to the cells that cover the external surface of the body or that line the internal cavities, plus those cells derived from the linings that form glands. Why most common cancers are epithelial origin? • These cells are the first point of contact of the body with environmental substances, either directly (squamous cells) or indirectly (glandular cells). • Epithelial cells usually have fast turn over rate, i.e., fast cell division, and their DNA can be damaged by carcinogens more often than non-dividing cells. Carcinoma: Squamous cell • Originates from stratified squamous epithelium of the skin, mouth, esophagus, and vagina, as well as from areas of squamous metaplasia, as in the bronchi or squamocolumnar junction of the uterine cervix. SCC is marked by the production of keratin. Skin Cancer Squamous Cell Carcinoma Carcinoma, Transitional Cell • Transitional cell carcinoma - arise from the transitional cell epithelium of the urinary tract, such as bladder. transitional cell carcinoma of the urothelium is shown here at low power to reveal the frond-like papillary projections of the tumor above the surface to the left. It is differentiated enough to resemble urothelium, but is a mass. No invasion to the right is seen at this point. TCC at high power Carcinoma: Adenocarcinoma • Adenocarcinoma - is carcinoma of glandular epithelium and includes malignant tumors of the gastrointestinal mucosa, endometrium, and pancreas; and is often associated with desmoplasia, tumor-induced proliferation of nonneoplastic fibrous connective tissue, particularly in adenocarcinoma of the breast, pancreas, and prostate. Prostate Ca Ovarian Ca Sarcoma • Sarcoma is a malignant tumor of mesenchymal origin • Sarcoma is often used with a prefix that denotes the tissue of origin of the tumor, as in osteosarcoma (bone), leiomyosarcoma (smooth muscle), rhabdomyosarcoma (skeletal muscle), and liposarcoma (fatty tissue). Classification of tumor according to stage Classification of Tumor according to its differentiation (grade) Gleason's breakthrough was to develop a reproducible description of the glandular architecture, to which one assigns a score from 1 to 5. The pathologist looks for a major pattern and a minor pattern to give a Gleason sum between 2 and 10. On the left is a picture adapted from Gleason's 1977 article demonstrating the changes in gland pattern as one goes from grade 1 to grade 5 cancer. The glands in grade 1 cancer are small and round. Grade 5 cancer is hardly forming glands at all. Gleason Grade 1 Prostate Cancer At right is Gleason 3 CaP. The glands are irregularly shaped. They are mixed in with some normal glands. This tumor is infiltrating the prostate. At higher magnification, there are nests of glands with no intervening stroma. This is characteristic of higher grade CaP Here is Gleason 5, or poorly differentiated cancer. You can see that it is invading the seminal vesicle (stage T4) The cells are not organized into glands, but are infiltrating the prostate as cords. Thank You!