Pathology of bone and mesenchymal differentiation all
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Questions and Answers

What is the primary function of giant cells in bone tumors?

  • Resorption of bone (correct)
  • Maintenance of bone growth
  • Production of bone matrix
  • Regulation of bone density

    • Which of the following is a characteristic of giant cell tumor of bone?

  • Predominance in older adults
  • Preferential location in the metaphysis or epiphysis (correct)
  • High metastatic potential
  • Occurrence in the skull

    • What is the significance of the mononuclear cell compartment in histological evaluation of giant cell tumor?

  • It comprises the tumor cells (correct)
  • It is the primary source of bone matrix
  • It is responsible for bone resorption
  • It provides information on the size and distribution of giant cells

    • Which of the following is a feature of giant cell-containing lesions of bone?

    <p>Most are not malignant</p> Signup and view all the answers

    What is the typical age range for giant cell tumor of bone occurrence?

    <p>Young adults</p> Signup and view all the answers

    What is the characteristic distribution of giant cells in giant cell tumor of bone?

    <p>Equally distributed</p> Signup and view all the answers

    Which of the following is a common location for giant cell tumor of bone?

    <p>Knee area</p> Signup and view all the answers

    What is the significance of giant cell tumor being intermediate in behavior?

    <p>It is locally aggressive and rarely metastasizing</p> Signup and view all the answers

    What is a characteristic of osteoclast-like giant cells?

    <p>They have more nuclei per cell</p> Signup and view all the answers

    What is the function of osteoclasts in bone remodeling?

    <p>To absorb and resorb bone</p> Signup and view all the answers

    What is the hallmark mutation of giant cell tumor of bone (GCTB)?

    <p>H3F3A G34</p> Signup and view all the answers

    What is the significance of the antibody for the mutant protein in H3F3A?

    <p>It can distinguish GCTB from chondroblastoma</p> Signup and view all the answers

    What is the characteristic of mononuclear cells in giant cell tumor of bone?

    <p>They are negative for H3F3A mutation</p> Signup and view all the answers

    How can solid aneurysmal bone cyst (ABC) be distinguished from giant cell tumor of bone?

    <p>By the presence of USP6 rearrangement</p> Signup and view all the answers

    What is the treatment for giant cell tumor of bone?

    <p>Curettage and excision</p> Signup and view all the answers

    What is the rate of lung metastases in giant cell tumor of bone?

    <p>Rare (less than 5%)</p> Signup and view all the answers

    What is the primary characteristic of giant cell tumors in terms of their behavior?

    <p>They are intermediate because they are locally aggressive and rarely metastasizing</p> Signup and view all the answers

    What is the typical location of giant cell tumors in the bone?

    <p>In the metaphysis or epiphysis of the bone</p> Signup and view all the answers

    What is the significance of the giant cells in histological evaluation?

    <p>They are equally distributed and provide information about the tumor's size</p> Signup and view all the answers

    What is the preferred location for giant cell tumors in the body?

    <p>Knee area and sacrum</p> Signup and view all the answers

    What is the characteristic of giant cell-containing lesions of bone?

    <p>They can be reactive, metabolic, or neoplastic</p> Signup and view all the answers

    What is the main difference between osteoclasts and osteoclast-like giant cells?

    <p>The number of nuclei per cell</p> Signup and view all the answers

    What is the significance of the mononuclear cell compartment in giant cell tumor?

    <p>It provides morphological criteria for the tumor</p> Signup and view all the answers

    What is the purpose of the deposition of H+ in the Howships lacuna?

    <p>To take away the minerals of the bone</p> Signup and view all the answers

    What is the typical age range for giant cell tumors?

    <p>Young adults</p> Signup and view all the answers

    What is the percentage of giant cell tumors that have H3F3A G34 mutations?

    <p>92%</p> Signup and view all the answers

    What is the significance of the giant cell's distribution in giant cell tumor?

    <p>It is equally distributed and provides information about the tumor's size</p> Signup and view all the answers

    What is the significance of the antibody for the mutant protein in H3F3A?

    <p>It is used to distinguish GCTB from CB</p> Signup and view all the answers

    What is the main difference between GCTB and CB?

    <p>The type of mutation in the histone H3.3 protein</p> Signup and view all the answers

    What is the characteristic of the mononuclear cells in giant cell tumor of bone?

    <p>They are attracted to the tumor but are not tumor cells themselves</p> Signup and view all the answers

    What is the significance of the USP6 rearrangement in solid aneurysmal bone cyst (ABC)?

    <p>It is used to distinguish ABC from GCTB</p> Signup and view all the answers

    What is the treatment for giant cell tumor of bone?

    <p>Curettage and excision</p> Signup and view all the answers

    Study Notes

    Giant Cell Containing Lesions in Bone

    • Not all giant cell-containing lesions are giant cell tumors; many types of tumors can contain giant cells.
    • Giant cell tumors are intermediate, locally aggressive, and rarely metastasizing.
    • Most giant cell-containing tumors are not malignant.
    • Almost any kind of lesion in bone can contain giant cells, sometimes numerous.

    Non-malignant Giant Cell Containing Lesions of Bone

    • Group includes reactive, metabolic, and neoplastic lesions.

    Location in Bone

    • Some tumors are only found in certain regions of the bone.
    • Giant cell tumors are typically found in the end of the bone (metaphysis or epiphysis).

    Giant Cell Tumor of Bone

    • Giant cell tumors mostly occur after closure of the growth plate.
    • They occur in young adults, with a slight preference for females.
    • Preferential locations include the knee area, sacrum, distal radius, but never in the skull.
    • Histological evaluation is based on morphological criteria of the mononuclear cell compartment, with an exception for the size and distribution of giant cells.

    Bone Cells Involved in Remodeling

    • Osteoclasts are normally involved in bone remodeling.
    • Other bone cells involved include osteoprogenitor cells (MSC), osteoblasts and lining cells, osteocytes, and osteoclasts.

    Osteoclast Function

    • Osteoclasts absorb bone, creating an acid environment that removes minerals from the bone.
    • They have a specific structure, including the Howship's lacuna.

    Giant Cell Tumor of Bone

    • Three cell types are involved: stromal cells, mononuclear cells, and multinuclear cells.
    • Sometimes, spindle cell changes or bone deposition (metaplastic bone formation) can be seen.

    Malignancy in Giant Cell Tumors

    • Giant cell tumor of bone is intermediate, with a small percentage being malignant.
    • Primary malignancy: high-grade sarcoma arising in/next to a giant cell tumor.
    • Secondary malignancy: rare, with end of chromosomes sticking together.
    • Mutation: H3F3A G34, which is a driver mutation and hallmark of GCTB.

    Mutation Detection and Diagnosis

    • H3F3A G34 mutations are found in 92% of giant cell tumors.
    • H3F3B K36M mutations are found in 95% of chondroblastomas.
    • Antibodies can be used to detect these mutations (IHC).
    • The antibody is specific for G34W (in H3F3A) and K36M (in H3F3B).

    Differential Diagnosis

    • Solid aneurysmal bone cyst (ABC) versus giant cell tumor: molecular diagnostics can be used to distinguish them.
    • Solid ABC: ~60% USP6 rearrangement, no H3F3A mutation.
    • GCTB: 69-96% H3F3A mutations, no USP6 rearrangements.

    Treatment of Giant Cell Tumor of Bone

    • Locally aggressive, with often local recurrences (40-60%).
    • Lung metastases are rare.
    • Treatment options: curettage, excision.

    Giant Cell Containing Lesions in Bone

    • Not all giant cell-containing lesions are giant cell tumors; many types of tumors can contain giant cells.
    • Giant cell tumors are intermediate, locally aggressive, and rarely metastasizing.
    • Most giant cell-containing tumors are not malignant.
    • Almost any kind of lesion in bone can contain giant cells, sometimes numerous.

    Non-malignant Giant Cell Containing Lesions of Bone

    • Group includes reactive, metabolic, and neoplastic lesions.

    Location in Bone

    • Some tumors are only found in certain regions of the bone.
    • Giant cell tumors are typically found in the end of the bone (metaphysis or epiphysis).

    Giant Cell Tumor of Bone

    • Giant cell tumors mostly occur after closure of the growth plate.
    • They occur in young adults, with a slight preference for females.
    • Preferential locations include the knee area, sacrum, distal radius, but never in the skull.
    • Histological evaluation is based on morphological criteria of the mononuclear cell compartment, with an exception for the size and distribution of giant cells.

    Bone Cells Involved in Remodeling

    • Osteoclasts are normally involved in bone remodeling.
    • Other bone cells involved include osteoprogenitor cells (MSC), osteoblasts and lining cells, osteocytes, and osteoclasts.

    Osteoclast Function

    • Osteoclasts absorb bone, creating an acid environment that removes minerals from the bone.
    • They have a specific structure, including the Howship's lacuna.

    Giant Cell Tumor of Bone

    • Three cell types are involved: stromal cells, mononuclear cells, and multinuclear cells.
    • Sometimes, spindle cell changes or bone deposition (metaplastic bone formation) can be seen.

    Malignancy in Giant Cell Tumors

    • Giant cell tumor of bone is intermediate, with a small percentage being malignant.
    • Primary malignancy: high-grade sarcoma arising in/next to a giant cell tumor.
    • Secondary malignancy: rare, with end of chromosomes sticking together.
    • Mutation: H3F3A G34, which is a driver mutation and hallmark of GCTB.

    Mutation Detection and Diagnosis

    • H3F3A G34 mutations are found in 92% of giant cell tumors.
    • H3F3B K36M mutations are found in 95% of chondroblastomas.
    • Antibodies can be used to detect these mutations (IHC).
    • The antibody is specific for G34W (in H3F3A) and K36M (in H3F3B).

    Differential Diagnosis

    • Solid aneurysmal bone cyst (ABC) versus giant cell tumor: molecular diagnostics can be used to distinguish them.
    • Solid ABC: ~60% USP6 rearrangement, no H3F3A mutation.
    • GCTB: 69-96% H3F3A mutations, no USP6 rearrangements.

    Treatment of Giant Cell Tumor of Bone

    • Locally aggressive, with often local recurrences (40-60%).
    • Lung metastases are rare.
    • Treatment options: curettage, excision.

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    Learn about the biology and characteristics of giant cell tumors, including GCTB, and how to distinguish them from other giant cell containing lesions in bone.

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