XXI - Musculoskeletal System

Question 1

Known as “brittle bone disease”.

Answer 1

Osteogenesis Imperfecta (TOPNOTCH)Robbins Basic Pathology,8th ed., p802

Question 2

This is a group of hereditary disorders caused by defective synthesis of type I collagen. Classic finding of a “blue sclerae” is seen in one type of this disorder.

Answer 2

Osteogenesis Imperfecta (TOPNOTCH)Robbins Basic Pathology,8th ed., p802

Question 3

Characterized by , disproportionate shortening of the proximal extremities, bowing of the legs, and a lordotic (sway-backed) posture.

Answer 3

Achrondroplasia (TOPNOTCH)Robbins Basic Pathology,8th ed., p802

Question 4

A group of rare genetic disorders characterized by reduced osteoclast-mediated bone resorption and therefore defective bone remodelling. Literally means “stone bone”.

Answer 4

Osteopetrosis(TOPNOTCH)Robbins Basic Pathology,8th ed., p802

Question 5

The hallmark of this disease is loss of bone which tends to be most conspicuous in trabecular bone. The bony trabeculae are thinner and more widely separated than usual, resulting in an increased susceptibility to fractures.

Answer 5

Osteoporosis (TOPNOTCH)Robbins Basic Pathology,8th ed., p804

Question 6

Characterized by repetitive episodes of frenzied, regional osteoclastic activity and bone resorption, followed by exuberant bone formation, and finally by an apparent exhaustion of cellular activity. Pathognomonic feature is a “mosaic pattern” of lamellar bone.

Answer 6

Paget Disease (Osteitis Deformans) (TOPNOTCH)Robbins Basic Pathology,8th ed., p806

Question 7

The hallmark of this disease is increased osteoclastic activity, with bone resorption. This leads to characteristic radiographic changes best seen along the radial aspect of the middle phalanges of the second and third fingers.

Answer 7

Hyperparathyroidism (TOPNOTCH)Robbins Basic Pathology,8th ed., p808

Question 8

Characterized by dead bone with empty lacunae is interspersed with areas of fat necrosis and insoluble calcium soaps. The cortex is usually not affected because of collateral blood supply.

Answer 8

Osteonecrosis (avascular necrosis)(TOPNOTCH)Robbins Basic Pathology,8th ed., p809

Question 9

Inflammation of the bone and marrow cavity.

Answer 9

Osteomyelitis(TOPNOTCH)Robbins Basic Pathology,8th ed., p809

Question 10

What do you call the dead entrapped bone seen in infected sites of bones affected with osteomyelitis?

Answer 10

Sequestrum(TOPNOTCH)Robbins Basic Pathology,8th ed., p809

Question 11

What do you call the shell of living tissue around a segment of devitalized bone?

Answer 11

Involucrum (TOPNOTCH)Robbins Basic Pathology,8th ed., p809

Question 12

Benign bone tumor characterized as exophytic growths attached to bone surface of the face and skull, which may histologically resemble normal bone.

Answer 12

Osteoma(TOPNOTCH)Robbins Basic Pathology,8th ed., p811

Question 13

Benign bone tumor that are cortical tumors, histologically described as interlacing trabeculae of woven bone. Characteristic symptom is pain. Common locations include the metaphyses of the femur and tibia.

Answer 13

Osteoid osteoma(TOPNOTCH)Robbins Basic Pathology,8th ed., p811

Question 14

These bone-forming lesions arise in vertebral transverse and spinous processes of the vertebral column, which may be histologically similar to osteoid osteoma.

Answer 14

Osteoblastoma(TOPNOTCH)Robbins Basic Pathology,8th ed., p811

Question 15

A bone-producing malignant mesenchymal tumor, characterized as gritty, gray-white tumors, often exhibiting hemorrhage and cystic degeneration. The production of mineralized or unmineralized bone (osteoid) by malignant cells is essential for diagnosis.

Answer 15

Osteosarcomas(TOPNOTCH)Robbins Basic Pathology,8th ed., p811

Question 16

These are relatively common benign hyaline cartilage-capped outgrowths attached by a bony stalk to the underlying skeleton.

Answer 16

Osteochondromas (TOPNOTCH)Robbins Basic Pathology,8th ed., p814

Question 17

These are benign tumors of hyaline cartilage, described as gray-blue, translucent well-circumscribed nodules. May be seen in metaphyseal regions of tubular bones of the hands and feet. On x-ray, the unmineralized nodules of cartilage produce well-circumscribed oval lucencies surrounded by thin rims of radiodense bone (O-ring sign).

Answer 17

Enchondromas (TOPNOTCH)Robbins Basic Pathology,8th ed., p814

Question 18

Chondromas seen on the bone surface.

Answer 18

Juxtacortical chondromas(TOPNOTCH)Robbins Basic Pathology,8th ed., p814

Question 19

These lesions arise within the medullary cavity of the bone to form an expansile glistening mass that often erodes the cortex. They exhibit malignant hyaline and myxoid cartilage.

Answer 19

Conventional chondrosarcomas (TOPNOTCH)Robbins Basic Pathology,8th ed., p814

Question 20

These tumors are characterized as viscous and gelatinous, with the matrix oozing from the cut surface. Spotty calcifications are typically present, with central necrosis creating cystic spaces.

Answer 20

Myxoid chondrosarcomas(TOPNOTCH)Robbins Basic Pathology,8th ed., p815

Question 21

Presents as sharply demarcated radiolucencies surrounded by a thin zone of sclerosis. They are gray to yellow-brown, and microscopically are cellular lesions composed of cytologically benign fibroblasts and macrophages. The fibroblasts classically exhibit a “storiform (pinwheel) pattern”.

Answer 21

Fibrous Cortical Defect and Nonossifying Fibroma (TOPNOTCH)Robbins Basic Pathology,8th ed., p815

Question 22

A benign tumor of the bone wherein all components of normal bone are present, but they fail to differentiate into mature structures. Curved trabeculae of woven bone mimick “Chinese characters” histologically.

Answer 22

Fibrous Dysplasia (TOPNOTCH)Robbins Basic Pathology,8th ed., p816

Question 23

Primary malignant small round-cell tumor of bone and soft tissue, characterized by Sheets of small round cells with scant, cleared cytoplasm, circled about a central fibrillary space or “Homer-Wright rosettes”.

Answer 23

Ewing sarcoma (TOPNOTCH)Robbins Basic Pathology,8th ed., p817

Question 24

A relatively uncommon benign tumor usually arising in individuals in their 20s to 40s. These are large and red-brown lesions with frequent cystic degeneration, composed of uniform oval mononuclear cells with frequent mitoses, with scattered osteoclast-type giant cells containing 100 or more nuclei.

Answer 24

Giant-cell tumors (GCTs)(TOPNOTCH)Robbins Basic Pathology,8th ed., p817

Question 25

These are the most common malignant tumor of bone.

Answer 25

Metastatic tumors (TOPNOTCH)Robbins Basic Pathology,8th ed., p818

Question 26

Pathways of metastasis to the bone.

Answer 26

1) direct extension, (2) lymphatic or hematogenous dissemination, (3) intraspinal seeding(TOPNOTCH)Robbins Basic Pathology,8th ed., p818

Question 27

Characterized by fibrillation and cracking of the articular cartilage matrix, bone eburnation, and bony outgrowths/spurs (osteophytes). Full-thickness portions of the cartilage are lost, and the subchondral bone plate is exposed.

Answer 27

Osteoarthritis (TOPNOTCH)Robbins Basic Pathology,8th ed., p819

Question 28

Characterized by a dense neutrophilic infiltrate permeating the synovium and synovial fluid. Long, slender, needle-shaped monosodium urate crystals are frequently found in the cytoplasm of the neutrophils as well as in small clusters in the synovium.

Answer 28

Acute gouty arthritis(TOPNOTCH)Robbins Basic Pathology,8th ed., p821

Question 29

Results from repetitive precipitation of urate crystals during acute attacks. The synovium becomes hyperplastic, fibrotic, and thickened by inflammatory cells, forming a pannus that destroys the underlying cartilage.

Answer 29

Chronic tophaceous arthritis (TOPNOTCH)Robbins Basic Pathology,8th ed., p821

Question 30

Formed by large aggregations of urate crystals surrounded by an intense inflammatory reaction of lymphocytes, macrophages, and foreign-body giant cells, attempting to engulf the masses of crystals. Pathognomonic feature of gout.

Answer 30

Tophi (TOPNOTCH)Robbins Basic Pathology,8th ed., p821

Question 31

Refers to multiple different renal complications associated with urate deposition, variously forming medullary tophi, intratubular precipitations, or free uric acid crystals and renal calculi.

Answer 31

Gouty nephropathy(TOPNOTCH)Robbins Basic Pathology,8th ed., p821

Question 32

Also known as chondrocalcinosis or-more formally-calcium pyrophosphate crystal deposition disease. The crystals are weakly birefringent, rhomboid in shape with blunted ends.

Answer 32

Pseudogout (TOPNOTCH)Robbins Basic Pathology,8th ed., p823

Question 33

Main causative agent of suppurative arthritis in children under 2 years old.

Answer 33

Haemophilus influenzae(TOPNOTCH)Robbins Basic Pathology,8th ed., p824

Question 34

Main causative agent of suppurative arthritis in older children and adults.

Answer 34

Staphylococcus aureus(TOPNOTCH)Robbins Basic Pathology,8th ed., p824

Question 35

Main causative agent of suppurative arthritis in late adolescence and young adulthood.

Answer 35

Neisseria gonorrhea(TOPNOTCH)Robbins Basic Pathology,8th ed., p824

Question 36

Individuals with sickle cell disease are prone to developing osteomyelitis and suppurative arthritis caused by this agent.

Answer 36

Salmonella(TOPNOTCH)Robbins Basic Pathology,8th ed., p824

Question 37

Arthritis caused by infection with the spirochete Borrelia burgdorferi, transmitted by deer ticks of the Ixodes ricinus complex.

Answer 37

Lyme arthritis (TOPNOTCH)Robbins Basic Pathology,8th ed., p824

Question 38

A small (<1.5 cm) cyst located near a joint capsule or tendon sheath, most commonly the wrist, which manifest as a firm to fluctuant pea-sized nodule.

Answer 38

Ganglion cyst(TOPNOTCH)Robbins Basic Pathology,8th ed., p825

Question 39

The most severe and the most common form of muscular dystrophy. Characterized by marked variation in muscle fiber size, caused by concomitant myofiber hypertrophy and atrophy. The definitive diagnosis is based on the demonstration of abnormal staining for “dystrophin” in immunohistochemical preparations.

Answer 39

Duchenne muscular dystrophy (DMD) (TOPNOTCH)Robbins Basic Pathology,8th ed., p825

Question 40

This can present as either acute or chronic proximal muscle weakness, and can precede the onset of other signs of thyroid dysfunction. Findings include myofiber necrosis, regeneration, and interstitial lymphocytes.

Answer 40

Thyrotoxic myopathy (TOPNOTCH)Robbins Basic Pathology,8th ed., p830

Question 41

This can occur with binge drinking, where there is an acute toxic rhabdomyolysis with accompanying myoglobinuria that can cause renal failure. On histology, there is myocyte swelling and necrosis, myophagocytosis, and regeneration.

Answer 41

Ethanol myopathy (TOPNOTCH)Robbins Basic Pathology,8th ed., p830

Question 42

An autoimmune disorder of the neuromuscular junction characterized by muscle weakness which first manifests in the extraocular muscles. Caused by circulating antibodies to the skeletal muscle acetylcholine receptors (AChRs).

Answer 42

Myasthenia gravis (TOPNOTCH)Robbins Basic Pathology,8th ed., p830

Question 43

This syndrome characteristically develops as a paraneoplastic process most commonly in the setting of small-cell lung carcinoma. Presents with muscle weakness secondary to decreased vesicle release in response to presynaptic action potential.

Answer 43

Lambert-Eaton Myasthenic Syndrome (TOPNOTCH)Robbins Basic Pathology,8th ed., p830

Question 44

Soft tissue tumor which presents as soft, gelatinous, grapelike masses on the surfaces of the bladder or vagina.

Answer 44

Sarcoma botryoides(TOPNOTCH)Robbins Basic Pathology,8th ed., p830

Question 45

It is the most common soft tissue sarcoma of childhood and adolescence, usually appearing before age 20.

Answer 45

Rhabdomyosarcoma (TOPNOTCH)Robbins Basic Pathology,8th ed., p831

Question 46

Diagnostic cell in rhabdomyosarcoma, characterized as round or elongated cells that may contain cross-striations visible by light microscopy.

Answer 46

Tadpole or strap cells(TOPNOTCH)Robbins Basic Pathology,8th ed., p831

Question 47

Soft, yellow, well-encapsulated masses of mature adipocytes; they can vary considerably in size. Histologically, they consist of mature white fat cells with no pleomorphism

Answer 47

Lipoma (TOPNOTCH)Robbins Basic Pathology,8th ed., p832

Question 48

Malignant neoplasms of adipocytes, which usually present as relatively well-circumscribed lesions. Diagnostic feature are lipoblasta, similar to fetal fat cells, with cytoplasmic lipid vacuoles that scallop the nucleus.

Answer 48

Liposarcomas (TOPNOTCH)Robbins Basic Pathology,8th ed., p833

Question 49

A self-limited, reactive fibroblastic proliferation that typically occurs in adults on the volar aspect of the forearm. Consists of plump, randomly arranged, immature-appearing fibroblasts in an abundant myxoid stroma. Not a true tumor.

Answer 49

Nodular Fasciitis(TOPNOTCH)Robbins Basic Pathology,8th ed., p833

Question 50

This develops in the proximal muscles of the extremities in athletic adolescents and young adults after trauma. Distinguished from other fibroblastic proliferations by the presence of metaplastic bone. Excision is curative.

Answer 50

Myositis Ossificans (TOPNOTCH)Robbins Basic Pathology,8th ed., p833

Question 51

Malignant neoplasms composed of fibroblasts. These are soft unencapsulated, infiltrative masses frequently with areas of hemorrhage and necrosis. Malignant spindle cells are arranged in a “herringbone pattern”.

Answer 51

Fibrosarcoma (TOPNOTCH)Robbins Basic Pathology,8th ed., p834

Question 52

These are relatively common benign lesions in adults presenting as circumscribed, small (

Answer 52

Benign Fibrous Histiocytoma (Dermatofibroma) (TOPNOTCH)Robbins Basic Pathology,8th ed., p834

Question 53

A variety of soft tissue sarcomas Characterized by considerable cytologic pleomorphism, the presence of bizarre multinucleate cells, and “storiform” architecture .

Answer 53

Malignant fibrous histiocytoma (MFH) (TOPNOTCH)Robbins Basic Pathology,8th ed., p834

Question 54

Benign smooth muscle tumors described as well-circumscribed neoplasms that can arise from smooth muscle cells anywhere in the body, but are encountered most commonly in the uterus.

Answer 54

Leiomyoma (TOPNOTCH)Robbins Basic Pathology,8th ed., p835

Question 55

These commonly present as firm, painless masses of the skin, deep soft tissues of the extermities and retroperitoneum. Histologically, they show spindle cells with cigar-shaped nuclei arranged in interweaving fascicles.

Answer 55

Leiomyosarcoma (TOPNOTCH)Robbins Basic Pathology,8th ed., p835

Question 56

What is the mineral that gives bone strength and hardness and is the storehouse for 99% of the body’s calcium, 85% of the body’s phosphorous, and 65% of the body’s sodium and magnesium?

Answer 56

Calcium Hydroxyapatite (TOPNOTCH)

Question 57

Of all the proteins in the bone matrix, which one is unique to the bone?

Answer 57

Osteocalcin (TOPNOTCH)

Question 58

Identify the bone cell: responsible for bone resorption

Answer 58

Osteoclast (TOPNOTCH)

Question 59

Identify the bone cell: most numerous than any other bone forming cell

Answer 59

Osteocytes (TOPNOTCH)

Question 60

Identify the bone cell: initiate the process of mineralization and express cell surface receptors that bind many hormones

Answer 60

Osteoblasts (TOPNOTCH)

Question 61

What is the functional unit of bone?

Answer 61

Osteoblast and Osteoclast act in coordination and are considered the functional unit of bone known as the Basic Multicellular Unit (TOPNOTCH)

Question 62

In what part of the bone can you see the histological abnormalities seen in achondroplasia?

Answer 62

Growth plate (TOPNOTCH)

Question 63

Gross appearance: lack a medullary canal and the end of long bones are bulbous (Erlenmeyer Flask Deformity) and misshapen. The neural foramina are small and compress exiting nerves

Answer 63

Osteopetrosis (TOPNOTCH)

Question 64

What is the main defect in Osteopetrosis?

Answer 64

Deficient Osteoblastic Activity (TOPNOTCH)

Question 65

Osteoporosis cannot be reliably detected in plain radiographs until how much of the bone mass is lost?

Answer 65

30-40% (TOPNOTCH)

Question 66

What is the histologic hallmark of Paget Disease of the bone?

Answer 66

Mosaic pattern of lamellar bone (Jigsaw pattern) (TOPNOTCH)

Question 67

A variety of tumor and tumor like conditions develop in pagetic bone. However, what is the most dreaded complication of this condition?

Answer 67

Sarcoma (Osteosarcoma > Malignant Fibrous Histiocytoma, or chondrosarcoma) (TOPNOTCH)

Question 68

80% of cases, what bone is involved in Paget DIsease?

Answer 68

Axial skeleton and proximal femur (TOPNOTCH)

Question 69

What is the most common site of tuberculous osteomyelitis?

Answer 69

Spine (thoracic and lumbar) > knees and hips (TOPNOTCH)

Question 70

Most cases of osteomyelitis reach the bone via what route?

Answer 70

Hematogenous (TOPNOTCH)

Question 71

What do you call a small intraosseous abscess that frequently involves the cortex and is walled off by reactive bone?

Answer 71

Brodie abscess (TOPNOTCH)

Question 72

What do you call the morphologic variant of osteomyelitis that typically develops in the jaw and is associated with extensive new bone formation that obscures much of the underlying osseous structures?

Answer 72

Sclerosing osteomyelitis of Garre (TOPNOTCH)

Question 73

What do you call a dead piece of bone?

Answer 73

Sequestrum (TOPNOTCH)

Question 74

Reactive woven or lamellar bone may be deposited and when it forms a sleeve of living tissue around a segment of devitalized bone, it is known as?

Answer 74

Involucrum (TOPNOTCH)

Question 75

Morphology: Edematous granulation tissue containing numerous plasma cells and necrotic bone

Answer 75

Congenital Syphilitic Bone infection and Acquired syphillis (TOPNOTCH)

Question 76

What is the most common primary malignant tumor of bone, exclusive of myeloma and lymphoma, and accounts for approximately 20% of primary bone cancers.

Answer 76

Osteosarcoma (TOPNOTCH)

Question 77

What are the 3 conditions associated with the development of osteosarcoma?

Answer 77

1. Paget disease2. Bone infarcts3. Prior irradiation (TOPNOTCH)

Question 78

What part of the bone do osteosarcomas usually arise?

Answer 78

Metaphyseal region of the long bone of the extremities, 60% occur about the knee. (TOPNOTCH)

Question 79

Morphology: Coarse, lacelike pattern of neoplastic bone produced by anaplastic malignant tumor cells

Answer 79

Osteosarcoma (TOPNOTCH)

Question 80

Morphology: sheets of uniform small, round cells that are slightly larger than lymphocytes with small amounts of clear cytoplasm.

Answer 80

Ewing Sarcoma (TOPNOTCH)

Question 81

Morphology: Presence of Homer Write rosettes ( tumor cells are arranged in a circle about a central fibrillary space)

Answer 81

Ewing Sarcoma (TOPNOTCH)

Question 82

The diagnostic cell of embryonal, alveolar, and pleomorphic variants of Rhabdomyosarcoma which contains eccentric eosinophilic granular cytoplasm rich in thick and thin filaments

Answer 82

Rhabdomyoblast (TOPNOTCH)

Question 83

Tadpole or strap cells are seen in what soft tissue tumor?

Answer 83

Rhabdomyosarcoma (TOPNOTCH)

Question 84

Morphology: characterized by malignant spindle cells that have cigar shaped nuclei arranged in interweaving fascicles.

Answer 84

Leiomyosarcoma (TOPNOTCH)

Question 85

Morphology: histological hallmark is the dual line of differentiation of tumor cells, epithelial like cells and spindle cells

Answer 85

Synovial Sarcoma (TOPNOTCH)

Question 86

Gross morphology: unencapsulated, infiltrative, soft, fish flesh masses, often having areas of hemorrhage and necrosis

Answer 86

Fibrosarcoma (TOPNOTCH)

Question 87

These cells mimic fetal fat cells and contain round clear cytoplasmic vacuoles of lipid that scallop the nucleus. Seen in liposarcoma.

Answer 87

Lipoblasts (TOPNOTCH)

Question 88

Morphology: consist of mature white fat cells with no pleomorphism

Answer 88

Lipoma (TOPNOTCH)

Question 89

Pathognomonic hallmark of gout

Answer 89

Tophi (TOPNOTCH)

Question 90

What are the most common cutaneous lesions seen in RA?

Answer 90

Rheumatoid Nodules (TOPNOTCH)

Question 91

The most important factors in the development of Osteoarthritis

Answer 91

Aging and mechanical effects (TOPNOTCH)

Question 92

Bone eburnation and joint mice are seen in what disease entity?

Answer 92

Osteoarthritis (TOPNOTCH)

Question 93

The most common cancers that metastasize to the bone are?

Answer 93

Prostate, breast, kidney, and lung (TOPNOTCH)

Question 94

What bones are most commonly involved in skeletal metastasis?

Answer 94

In descending order: Axial skeleton ( vertebral column, pelvis, ribs, skull, and sternum), proximal femur, and humerus (TOPNOTCH)

Question 95

Skeletal metastases are typically multifocal, however, what carcinomas that metastasize to the bone are notorious for producing solitary lesions?

Answer 95

Ca of Kidney and Thyroid (TOPNOTCH)

Question 96

morphology: uniform oval mononuclear cells that have indistinct cell membranes and appear to grow in syncitium with scattered numerous osteoclast type giants cells having 100 or more nuclei that have identical features to those of the mononuclear cells

Answer 96

Giant cell Tumor (TOPNOTCH)

Question 97

Morphology: trabeculae mimic chinese characters

Answer 97

Fibrous Dysplasia (TOPNOTCH)

Question 98

Morphology: Storiform pattern or pinwheel pattern created by benign spindle cells with scattered osteoclast

Answer 98

Fibrous cortical defect and nonossifying fibroma (TOPNOTCH)

Question 99

What is the primary characteristic of osteosarcoma?

Answer 99

The formation of bone by the tumor cells (TOPNOTCH)

Question 100

The combined picture of increased bone cell activity, peritrabecular fibrosis, and cystic brown tumors is the hallmark of what disease of abnormal mineral homeostasis?

Answer 100

Hyperparathyroidism (Generalized osteitis fibrosa cystica or von Recklinghausen disease of the bone) (TOPNOTCH)

Question 101

What is the xray pattern that is virtually diagnostic of hyperparathyroidism?

Answer 101

Subperiosteal resorption producing thinned cortices in the middle phalanges of the index and middle finger and loss of the lamina dura around the teeth (TOPNOTCH)

Question 102

What is the most important prognostic feature of a bone sarcoma?

Answer 102

Histological grade (TOPNOTCH)

Question 103

O ring sign is seen in what cartilage forming tumor?

Answer 103

Chondroma (TOPNOTCH)

Question 104

Morphology: chicken wire pattern of mineralizaton

Answer 104

Chondroblastoma (TOPNOTCH)

Question 105

Myositis ossificans is distinguised from the other fibroblastic proliferations by the presence of what structure?

Answer 105

Metaplastic bone (TOPNOTCH)