Bone and Soft Tissue Pathology, Clin Core Lecture 7

What are the steps of handling bone tumor resection specimens?

1. Orient with surgeon (ink margins)

2. Sample tumor, normal interface and heterogenous zones

3. Include soft tissue cuff, skin if PRESENT

4. Selective decalcification, to retain antigenicity

5. Tumor mapping (effectiveness of prior treatment needs to be evaluated)

What are the 3 subtypes of osteosarcoma?

1. Osteoblastic

2. Chondroblastic

3. Fibroblastic

Osteosarcoma is high-grade in what age group?

Teens

Osteosarcoma can metasitize to:

Lung and liver

This is the malignant over-production or aberrant production of bone

Osteosarcoma

How is osteosarcoma typically found in young patients?

From the pathological fracture

Unexpected fracture when playing sports, walking, or other basic tasks

What 4 things determine the grading and staging of osteosarcoma?

1. Grade drives stage (low vs. high)

2. Assess the size, compartment, skip lesions, metastasis

3. Response to chemotherapy (% necrosis) is prognostic

4. Margins: aim for negative, document closest margin

What age group typically is diagnosed with Ewing sarcoma?

10-20 year old

What are the three treatment options for Ewing Sarcoma?

1. Neoadjuvant therapy

2. Surgical resection

3. Radiation therapy

Genetically, what is the mutation in Ewing Sarcoma?

EWSR1::FLI1 fusion

What other cancers are similar to Ewing Sarcoma but are ruled out genetically?

1. Lymphoma

2. Small cell osteosarcoma

3. Rhabdomyosarcoma

On the skin surface, what is evident of Ewing Sarcoma?

Onion-skin, peristeal reaction

What is Ewing Sarcoma?

Small round blue cell tumor, typically found in the diaphyseal

What are some characteristics of Ewing Sarcoma?

1. Presents as bone pain, swelling and fever

2. Can metastasize

3. Potential pathological fracture

4. Often in the femur or near femoral head, but can present elsewhere (RIBS, SPINE, HUMERUS, PELVIC BONES)

This is fibrious, scar-like tissue that fills the spaces around the woven bone. It is depicted in radiology as ground glass, exhibiting irregular woven bone.

Fibrous dysplasia

This is immature bone with random, disorganized collagen fibers, bony elements are surrounded by osteoblasts that are producing bone. Present during fetal development, a fracture site, but not found in the ADULT HUMAN SKELETON.

Woven bone

This is mature bone, organized with embedded osteocytes. Very few if any osteoblasts are present. Appears to have concentric rings, similar to tree

Lamellar bone

Monostotic fibrous dysplasia of bone means:

Only one bone is affected, usually a long bone

Monostotic fibrous dysplasia of bone is typically found in what age group?

Children, usually stops at puberty

Polyostotic fibrous dysplasia of bone means:

Involving multiple bones (may remain for whole life, widespread, more severe)

How can fibrous dysplasia affect the bone marrow?

Expansile intermedullary mass in the bone marrow, resulting in severely weakened bone (bone deformities and pathologic fractures)

What are 3 treatments of fibrous dysplasia of bone?

1. Management of symptoms/pain

2. Surgically stabilizing the bones

3. Possible bone resections for pathological fracture

Metastatic and hematologic bone lesions typically spread to:

Breast

Prostate

Lung

Kidney

Thyroid

Myeloma and plasmacytoma affect the:

plasma cell sheets

This is known as “lytic bone lesions”, essentially the destruction of bone

Multiple myeloma

What is the mechanism of multiple myeloma?

1. Abnormal plasma cells signal the increased release of osteoclasts (breaking down of bone)

2. Cause an imbalance, more osteoclasts than osteoblasts

3. Facilitates the breakdown of bone, the imbalance results in a lack of new bone formation by osteoblasts

These types of cancers can also metastasize to bone:

Lung, breast, kidney tumors

Hematologic malignancies, other than MM can develop or arise in bones, such as:

Lymphoma

What are the steps in grossing bone resections for tumor?

1. What is present? (bone only, or bone with overlying soft tissue, skeletal muscle, fat and skin)

2. Orientation

3. Measurements of the bone and soft tissue (if present)

4. What are the margins?

5. Inking scheme to orientation

6. Section bone, prior to fixation

7. Submit sections of the nearest margins: PROXIMAL AND DISTAL BONE MARGINS, RADIAL MARGIN, AND SOFT TISSUE MARGINS AS ORIENTED

8. If there is a primary tumor, many sections will be submitted to assess prior treatment effect.

9. If soft tissue is present, sections closest to margins, sections demonstrating tumor extension

10. Use less concentrated decal to decalcify bone, to protect antigenicity for IHC

What are the 3 matrix clues?

1. Osteoid

2. Chondroid

3. Fibrous

What are the 6 bone tumor classifications?

1. Osteoid-forming tumors

2. Chondroid-forming tumors

3. Fibro-osseous tumors

4. Small round blue cell tumors

5. Giant cell-rich lesions

6. Vascular tumors