Pathology of Sarcoma ELEANOR CHEN, MD, PHD, ASSISTANT PROFESSOR DEPARTMENT OF PATHOLOGY UNIVERSITY OF WASHINGTON
Presentation outline • Background and epidemiology of sarcomas • Sarcoma classification • Sarcoma grading and staging (to predict clinical prognosis) • Role of pathologists in sarcoma treatment
Sarcoma • A cancer that starts in the connective tissues of the body, e.g. muscle , bone, tendons, fat, nerves and tissues around joints. • Sarcoma can be found anywhere in the body. • Most frequent sites: legs, arms, abdomen and chest
Key sarcoma statistics • About 12,390 new sarcomas will be diagnosed (6,890 cases in males and 5,500 cases in females). Lung Cancer: 222,500 new cases • 4,990 people in the U.S. (2,670 males and 2,320 females) are expected to die of sarcomas. Sarcoma: 12,390 new cases
Etiology • The etiology of most sarcomas is unknown. • Potential causes: • Chemical carcinogens • Radiation • Viral infection • Genetic susceptibility
Age distribution • Sarcoma can occur at any age, but more common with increasing age (median age: 65) • Age-related incidences vary. • Embryonal rhabdomyosarcoma in children. • Bone sarcomas (e.g. osteosarcoma and Ewing’s sarcoma) in children and young adults • Some sarcoma types (e.g. undifferentiated pleomorphic sarcoma, liposarcoma, leiomyosarcoma and myxofibrosarcoma) in the elderly.
Sarcoma classification • At least 50 sarcoma types have been described! • Many sarcomas are named based on the type of tissue they resemble.
Leiomyosarcoma Smooth Muscle
Sarcomas that do not resemble any tissue type Interstitial Cell of Cajal Gastrointestinal Stromal Tumor Malignant Peripheral Nerve Sheath Tumor (MPNST)
Sarcomas with overlapping morphologic features Ewing Sarcoma Alveolar Rhabdomyosarcoma
Sarcomas mimicking other cancer types Small Cell Carcinoma Ewing Sarcoma Small Cell Lymphoma
Immunohistochemistry Fluorescence In Situ Hybridization Perform additional molecular tests to confirm a sarcoma type
Grading of sarcomas • Histologic grade correlates with malignant biological potential. • A high-grade sarcoma shows a more aggressive clinical course compared to a low-grade sarcoma.
Sarcoma grading criteria Cytologic Atypia Necrosis (Cell Death) Mitosis (Cell Division) SARCOMA Normal Tissue
Low Grade Fibromyxoid Sarcoma High Grade Leiomyosarcoma
High-grade Pleomorphic Sarcoma Low-grade myxofibrosarcoma Quiz time! High-grade or low-grade sarcoma?
Some sarcomas are not assigned a grade • Sarcomas with indolent behavior but metastatic potential: • Alveolar soft part sarcoma, angiomatoid fibrohistiocytic tumor, ossifying fibromyxoid tumor • Sarcomas with aggressive behavior: • Epithelioid sarcoma, pleomorphic liposarcoma, undifferentiated pleomorphic sarcoma, Ewing sarcoma
Staging of sarcomas • The process of determining whether a sarcoma has spread • Information needed for staging sarcomas: • Histologic grade • Tumor size • Anatomic location/depth (superficial or deep) • Regional lymph node involvement • Distant organ involvement (metastasis)
What does a pathologist do? Pathologists specialize in interpreting laboratory tests and evaluating tissue samples from patients.
Role of pathologist in treatment of sarcoma A Pathologist….. Determines the disease and cancer type in the tissue and work with other members of the care team to recommend the best treatment strategy. • Interprets biopsy samples to determine whether the tissue is benign or malignant (cancerous). •
Role of pathologist in treatment of sarcoma A Pathologist….. • Renders final pathology reports. • Some pathologists are research scientists, translating bench findings to clinical applications.
Summary • Sarcoma is a rare cancer that can occur anywhere in the body, but more frequently in the extremities, chest and abdomen. • Incidence of sarcoma increases with age, some sarcoma types occur frequently in specific age groups. • Some sarcoma types resemble certain tissue types, and some need additional ancillary tests to confirm their identity. • Grading and staging can help predict clinical course of the disease.
THANK YOU! Any questions?