| A | B |
|---|
| Chondrosarcoma | Older males |
| Chondrosarcoma | Central location |
| Chondrosarcoma | Large destructive mass |
| Chondrosarcoma | Glistening white tissue |
| Chondrosarcoma | No osteoid |
| Osteochondroma | Exostosis |
| Osteochondroma | Protruding “mushroom” |
| Osteochondroma | Enchondral bones only |
| Osteochondroma | Metaphysis near growth plate (knee) |
| Osteochondroma | Young males |
| Osteochondroma | EXT gene inactivation in growth plate chondrocytes |
| Osteosarcoma | Osteoid formation by malignant cells |
| Osteosarcoma | Teenage boys, knee metaphysis |
| Osteosarcoma | RB gene (13q14) in 60% |
| Osteosarcoma | 2nd peak in older adults with abnormal bone (Paget disease) |
| Chondroblastoma | Chondroblastoma |
| Chondroblastoma | Tennage boy, knee, Epiphysis |
| Chondroblastoma | Monotonous small Chondroblasts |
| Chondroblastoma | Lacelike matrix calcifies (chicken wire) |
| Chondroblastoma | Recur locally |
| Chondroblastoma | Rare lung metastasis à Curettage emboli |
| Giant cell Tumor of bone | Giant cell tumor of bone |
| Giant cell Tumor of bone | Epiphysis (starts in metaphysic, where it stays if epiphyseal plate still present) |
| Giant cell Tumor of bone | Young adults, knee |
| Giant cell Tumor of bone | Mononuclear Cell is proliferative component |
| Giant cell Tumor of bone | Fuse to form osteoclast-like giant cells (osetoclastoma) |
| Giant cell Tumor of bone | Benign but locally agressive |
| Chondromyxoid fibroma | Mistaken for sarcoma |
| Chondromyxoid fibroma | Teen/ y.a male; metaphysis of long bones |
| Chondromyxoid fibroma | Hyaline cartilage, fribrous septa, and myxoid regions with stellate cells; can show cytologic atypia |
| Chondromyxoid fibroma | May recur, never malignant |
| osteoid osteoma | Males 10-30 ;Lower limb |
| osteoid osteoma | < 2cm |
| osteoid osteoma | Pain, nocturnal |
| osteoid osteoma | Prostaglandin E2 |
| osteoid osteoma | Aspirin helps |
| osteoid osteoma | Radiolucent nidus with sclerotic border |
| osteoblastoma | Males: 10-30; Spine and skull |
| osteoblastoma | Larger than 2 cm |
| osteoblastoma | Less specific pain |
| osteoblastoma | No PGE2 |
| osteoblastoma | Aspirin doesn’t help |
| osteoblastoma | Radiolucent nidus with sclerotic border |
| Ewing Sarcoma and PNET | Small round blue cell tumor |
| Ewing Sarcoma and PNET | Teens; Diaphysis (Medullary cavity) |
| Ewing Sarcoma and PNET | Systemic symptoms (fever) |
| Ewing Sarcoma and PNET | T(11;22): results in fusion gene, a dominant oncogene leading to cell proliferations |
| PNET | shows neural differentiation |
| Enchodroma | Young Adults; short tubular bones of hands and feet |
| Enchodroma | Benign cartilage |
| Enchodroma | Probably arise from cartilaginous rests |
| Enchodroma | Multiple = Ollier disease |
| Enchodroma | Multiple + hemangiomas = Maffucci syndrome |
| Enchodroma | Chondroma – bone surface, less common |
| Fibrous dysplasia | YA, Adolescents; Benign intramedullary mass-like lesion |
| Fibrous dysplasia | Curvilinear trabeculae (Chinese characters) of woven bone; no mature osteoblasts; cellular fibroblastic stroma |
| Fibrous dysplasia | Monostotic > Polyostotic > McCune-Albright (café au lait spots and endocrinopathies |
| Fibrous dysplasia | Postzygotic, somatic mutation for G-protein à increased activity of cAMP à increase cell function; distribution of mutation determines degree |
| Pagets Disease | Mosaic pattern – prominent irregular cement lines |
| Pagets Disease | Stages: osteoclastic > mixed > osteoblastic > quiescent (osteosclerotic) |
| Pagets Disease | Possibly viral; paramyxovirus (measles) |
| Pagets Disease | Polyostotic >>> monostotic |
| Pagets Disease | Hypervascular à hear failure |
| Pagets Disease | Secondary sarcoma |
| Gout | Monosodium urate crystal deposition |
| Gout | Purine metabolism (usually unknown defect; salvage pathway: HGPRT) |
| Gout | Crystals precipitate in joints à activate inflammation |
| Gout | Tophi in joints, surrounding soft tissue |
| Gout | Acute and chronic arthritis; nephropathy |
| Ganglio (cyst) | Wrist, usually dorsum |
| Ganglio (cyst) | Near tenosynovium or joint capsule |
| Ganglio (cyst) | Contains thick fluid similar to synovial |
| Ganglio (cyst) | No true cell lining (synovial or otherwise) |
| Ganglio (cyst) | Degenerative vs. synovial-related (traumatic?) |
| Giant cell tumor of tendon sheath | Joint equivalent is PVNS (usually knee) |
| Giant cell tumor of tendon sheath | Most common mesenchymal neoplasm of hand |
| Giant cell tumor of tendon sheath | Smaller cells are proliferative component |
| Giant cell tumor of tendon sheath | Giant cells variable in prominence |
| Giant cell tumor of tendon sheath | Variegated (hemosiderin = brown; foamy macrophages = yellow) |
| Superficial Fibromatoses | Palmar (Dupuytren’s), plantar, and penile (Peyronie’s) |
| Superficial Fibromatoses | M>F |
| Superficial Fibromatoses | Hypercellular (Myofibrobroblasts?) |
| Superficial Fibromatoses | Not aggressive |
| Deep Fibromatoses | Desmoid tumor |
| Deep Fibromatoses | Abdominal ones related to pregnancy |
| Deep Fibromatoses | Extra/intra-abdomical |
| Deep Fibromatoses | Locally aggressive |
| Deep Fibromatoses | Difficult to excise |
| Myositis ossificans | Ossified soft tissue mass |
| Myositis ossificans | Proximal extremities, young, athletic |
| Myositis ossificans | Usually post trauma |
| Myositis ossificans | Zonation: central fibroblastic zone maturing peripherally to trabecular bone |
| Myositis ossificans | Differential: extraskeletal osteosarcoma (no zonation, older patients) |
| Nodular Fasciitis | Non-ossified soft tissue mass |
| Nodular Fasciitis | Forearm |
| Nodular Fasciitis | History of trauma uncommon |
| Nodular Fasciitis | Mitotically active cellular proliferation of fibroblasts (“pseudosarcoma”) |
| Malignant fibrous histiocytoma | Has giant cells |
| Cytokeratin: | usually a marker of epithelial cell |
| Synovial Sarcoma | Bad prognosis |
| Synovial Sarcoma | Has cytokeratin |
| Synovial Sarcoma | Biphasic: spindled and epithelial-like |
| Synovial Sarcoma | T(x;18) |
| Synovial Sarcoma | Usually near joints of limbs, but not directly from synovium |
| Synovial Sarcoma | Adolescents and young adults, M>F |
