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).

• 4,990 people in the U.S. (2,670 males and 2,320 females) are expected to die of sarcomas.

Lung Cancer: 222,500 new cases

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

Gastrointestinal Stromal Tumor Malignant Peripheral Nerve Sheath Tumor (MPNST)

Interstitial Cell of Cajal

Sarcomas with overlapping morphologic features

Ewing Sarcoma Alveolar Rhabdomyosarcoma

Sarcomas mimicking other cancer types

Ewing Sarcoma

Small Cell Lymphoma

Small Cell Carcinoma

Perform additional molecular tests to confirm a sarcoma type

Immunohistochemistry Fluorescence In Situ Hybridization

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 Mitosis (Cell Division) Necrosis (Cell Death)

SARCOMA

Normal Tissue

Low Grade Fibromyxoid Sarcoma

High Grade Leiomyosarcoma

Quiz time! High-grade or low-grade sarcoma?

Low-grade myxofibrosarcoma High-grade Pleomorphic 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

• 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).

A Pathologist…..

Role of pathologist in treatment of

sarcoma • Renders final pathology reports.

• Some pathologists are research scientists, translating bench findings to clinical applications.

A Pathologist…..

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?