Musculoskeletal Disorders

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Block B2 - Neuromusculoskeletal Problems


Pathological Anatomy
Office:4th floor, Radiopoetro
Lab:4th floor, Radiopoetro
Work-plan:No.
Pre-test:10 multiple-choice questions.
Post-test:5-10 written questions.
Lab Report:Yes.


Structure of a long bone.
Anatomy of hand and knee joint

For batch 2011, Osteoma and Fibrous Dysplasia were not included even though they appeared in the block book. There was just one PA session for batch 2011 that included the remaining specimens.

Specimens[edit]

Synovial Sarcoma[edit]

  • aka. Synovial cell sarcoma, malignant synovioma, tendosynovial sarcoma.
  • Origin: synoviocyte type B.
    • (Classic) Biphasic: epithelial-like cells as well as spindle cells.
    • Monophasic: just spindle cells.
  • Spindle cells appear as elliptical/ovoid in shape. Epithelial cells are cuboidal to columnar and tend to form glands.
  • IHC:
    • Spindle: BCL2, vimentin, CD99.
    • Epithelial: EMA, CK7, CK19, and CD34 (-).
  • To identify: look for many flat or oval shaped cells.

Osteosarcoma[edit]

  • aka. Osteogenic sarcoma, conventional sarcoma, classical sarcoma.
  • Origin: osteoblast.
  • Atypical and pleomorphic tumor cells with large, hyperchromatic nucleus.
  • Neovascularization.
  • Mostly found in young age (<20 years old) and then in elderly (with Paget's disease). Affects males:females = 3:2.
  • Mostly found in the medulla area of metaphysis areas of long bones (e.g. femur, tibia, humerus, pelvis)
  • IHC: Vimentin, collagen type I, II, IV.
  • Cancer cells produce bone matrix.
  • Multinucleated giant cells are seen near necrosis and calcification areas.
  • Codman's triangle: shadow between cortex and raised ends of periosteum (due to reactive bone formation).
  • Variants:
    • Osteoblastic
    • Fibroblastic: pure spindle cell growth with minimal matrix.
    • Chondroblastic: malignant appearing cartilage with peripheral spindling and osteoid production.
  • Differential diagnosis: osteoblastoma, fibrous dysplasia, fibrosarcoma, and chondrosarcoma.
  • Identified using: p53 gene and RB (retinoblastoma) gene.
  • To identify: similar to synovial sarcoma in that there are elongated oval/flat shaped cells, and similar to GCT in that there are giant multinucleated cells, but in this case there's also osteoid area (large, empty, pink areas).

Giant Cell Tumor of Tendon Sheath[edit]

  • aka. Localized nodular tenosynovitis, tenosynovial giant cell tumor, xanthogranuloma, benign synovioma, and fibrous histiocytoma of tendon sheath.
  • Most common mesenchymal neoplasm of the hand.
  • Multinucleated giant cells are formed by the fusion of mononuclear cells (i.e. histiocyte). Thus, the origin of this tumor is histiocytes.
  • Pathogenesis involves translocation of chromosomes leading to overexpression of CSF-1.
  • Types:
    • Localized type: mature collagen capsule surrounding the tumor. Common. Slow growing. Usually affects flexor surface of fingers.
    • Diffuse type: no capsule and grows as expansive sheet. Rare. Aggressive. aka PVNS. Usually affects knee (80%).
  • Soap bubble appearance on x-ray.
  • Usually affects fingers, wrists, and toes of people aged 20-50 (sometimes said to be 20-40 and 30-50).
  • Usually affects epiphysis and metaphysis.
  • Polygonal/polyhedral cells, often with hemosiderin (brown color) and siderophages (cells that eat hemosiderin). Hemosiderin is caused by hemorrhage.
  • IHC: clusterin, apoprotein, CD68, CD45.
  • This neoplasm can develop into osteosarcoma. Osteosarcoma also features multinucleated giant cells.
  • Differential diagnosis: epithelioid sarcoma.
  • To identify: look for giant cells (large cell with a bunch of nuclei inside it) and also hemosiderin (pink dots) and hemosiderin pigment (dark brown chunks).

Osteomyelitis[edit]

  • Inflammation of bone or bone marrow. Acute or chronic.
  • Inflammatory cells such as neutrophils, macrophages, plasma cells, and lymphocytes. Hemorrhage, necrosis, and new bone formation.
  • Types: pyogenic, tuberculous, and vertebral.
  • Pyogenic:
    • Most common pathogen: S. aureus. Others include E. coli (usually neonates), N. gonorrhoeae, H. influenzae, and Salmonella sp (usually sickle cell disease patients).
    • Most common site: metaphysis of long bones (knee, ankle, and hip).
    • Brodie abscess: reactive bone from the periosteum and endosteum, which surrounds and contains the infection.
    • Sequestrum: fragment of necrotic bone embedded in pus.
    • Involucrum: a lesion in which periosteal new bone formation forms a sheath around the necrotic sequestrum.
  • Tuberculous:
    • Pott disease: tuberculous osteomyelitis at vertebrae.
    • Common site: synovium.
  • Gold standard: bone biopsy.
  • Marjolin's ulcer: squamous cell carcinoma on the skin as a result of chronic osteomyelitis.

Chondroma[edit]

  • Benign neoplasm of hyaline cartilage.
  • Origin: chondrocyte.
  • Majority of patients between 20 and 40 years old.
  • Enchondroma: medulla of bone.
  • Periosteal chondroma: surface of the bone.
  • O-ring sign on x-rays: oval lucencies surrounded by thin rims of radiodense bone. aka. "c-sign".
  • Targets metaphysis of short tubular bones (e.g. metacarpals and proximal phalanges of hands). Also, less frequently, chondromas can target long tubular bones (e.g. proximal humerus and distal femur) as well.
  • Cytoplasm is granular eosinophilic.
  • Nuclei are small and round with condensed chromatin.
  • Foci of myxoid degeneration, calcification, and endochondral ossification are common.
  • Enchondromatosis: multiple enchondromas (2 or more).
  • Ollier disease: multiple enchondromas, often on one side of the body.
  • Maffucci syndrome: multiple enchondromas related to hemangiomas in soft tissue.
  • To identify: fewer cells in large, empty, pink spaces.

Osteoma[edit]

Fibrous Dysplasia[edit]

  • aka. Fibrocartilaginous dysplasia, generalized fibrocystic disease of the bone.
  • Chinese character appearance, microscopically.
  • Ground-glass appearance, macroscopically.


Pretests[edit]

Batch 2011 Regular, pretest (Indonesian)

Batch 2011[edit]

  1. Malignant mesenchymal cells in matrix pattern. Osteosarcoma.
  2. Chondroma
  3. Affects wrists to fingertips and toes. GCT.
  4. Inflammation of bone and marrow. Osteomyelitis.
  5. Malignant ... Synovial sarcoma.
  6. 50% of synovial sarcomas occur in the knee. True.
  7. What color does ??? stain? Gray-blue.
  8. ??? is easily confused with? Fibrosarcoma.
  9. Radiologic appearance? Involcrum.
  10. Polyhedral cells are found in? GCT.


Links[edit]