Page 609 - Concise Pathology for Exam Preparation ( PDFDrive )

594 SECTION II Diseases of Organ Systems

Gross Pathology
• Lesion is generally small, less than 4 cm in diameter, granular and brown.
• Larger lesion (5–10 cm) referred to as nonossifying fibroma.

Microscopy
• Cellular masses of fibrous tissue showing storiform pattern interspersed with numerous
multinucleate osteoclast-like giant cells.
• Focal areas showing haemosiderin-laden macrophages and foam cells.

JOINTS
Functions of Joints
• Enable movement and provide mechanical support
• Solid joints provide structural integrity
• Cavitated joints are lined by synovial cells and aid in movement
Components of Synovial Lining
• Type A cells: Macrophage-like; synthesize hyaluronic acid
• Type B cells: Fibroblast-like; produce various proteins

Functions of Articular Cartilage
• Friction-free movement in joints
• Spreading the load evenly in weight-bearing joints, so that the underlying bones absorb
shock and weight without being crushed.

Q. Outline the aetiopathogenesis, clinical and pathological features
of osteoarthritis (OA).
Ans. OA or degenerative joint disease is characterized by age and mechanical stress
dependent progressive erosion of articular cartilage. It is more common in females than
in males and may be primary or secondary in origin. Secondary osteoarthritis occurs
following metabolic disorders (ochronosis, haemochromatosis), deformity, trauma,
fracture, obesity, severe mechanical stress and diabetes.

Clinical Features
• OA primarily targets weight-bearing joints (hip, knee, distal interphalangeal joints of
hands and lower lumbar vertebrae).
• May be asymptomatic or presents with the following manifestations:
- Deep aching pain which worsens with movement
- Stiffness and limitation of movement with crepitus (crackling sound)
- Bone eburnation (when cartilaginous protection is reduced, subchondral bone may
be exposed and damaged. This is followed by regrowth leading to a proliferation of
ivory-like, dense, reactive bone in central areas of cartilage)
- Small fractures in articular bones
- Atrophy of regional muscles and laxity of ligaments (consequent to decreased
movement because of the pain)
- Degenerative changes (result in formation of hard, bony, painless enlargements called
Heberden’s nodes at the base of distal interphalangeal joint of the fingers and Bouchard’s
nodes on the proximal interphalangeal joints).
• Reactive bone formation at the margins of the joints (osteophytes). Osteophytes in spine
may cause compression of cervical/lumbar nerve roots causing pain, muscle spasms and
neurological deficit.

mebooksfree.com