Pathology Review Carousel
Bone, Joint and Soft Tissue

---

---

Image	Slide	Tissue	Mag	Feature
	1	Retroperitoneal soft tissue	LP	Well differentiated liposarcoma: Fat cells interspersed with collagen can be seen at low power. A higher magnification is necessary to see the diagnostic lipoblasts.
	2	Same	MP	Well differentiated liposarcoma: Adipose tissue resembling a lipoma with interspersed immature lipoblasts (fat cells with one or more lipid droplets in the cytoplasm distorting large hyperchromatic nuclei).
	3	Same	HP
	4	Hands	Gross	Rheumatoid arthritis: dots). Radial deviation of the wrist (not striking in this example) and the ulnar deviation of the fingers from the proximal interphalangeal and metacarpophalangeal joints characteristic of RA.
	5	Synovium	LP	Rheumatoid arthritis: diffuse proliferative synovitis or pannus which is the inflamed synovium which covers the articular surface in RA. Note the multi-layering of the synovial lining cells and the infiltrate of mononuclear inflammatory cells (small blue dots).
	6	Synovium	MP	Rheumatoid arthritis: fibrin intermixed with inflammatory cells and possible foci of necrosis.
	7		MP	Rheumatoid arthritis: Marked inflammatory infiltrate of mononuclear cells consisting of macrophages, lymphocytes and lots of plasma cells. (Germinal centers can sometimes be seen).
	8	Arm		Osteomyelitis: Bone destruction from osteomyelitis, more prominent in the distal 1/2 of bone with a sleeve of new bone formed beneath the periosteum or involucrum. While the diaphysis is involved, the site of origin was most likely the distal metaphysis with more proximal spread.
	9	Distal Femur	Roentgenogram	Pedunculated osteochondroma. Characteristic features include continuity of the cortex and medullary cavity with their counterparts of the parent bone and the stalk points away from the adjacent joint surface.
	10		LP	Osteochondroma. Somewhat disorganized cartilage cap overlying cancellous bone. Thought to arise as a developmental defect of the epiphyseal plate.
	11	Same	MP	.SAME
	12	Hand	Roentgenogram	Chondroma. Well defined, largely radiolucent, lobulated lesion with punctate calcifications in the proximal phalanx of the ring finger. Location and small size help in differentiating this from a chondrosarcoma on roentgenogram.
	13	Bone of hand	LP	Chondroma. Somewhat disrupted section. Note pale lobules of disorganized cartilage separated by thin rims of pinker bone.
	14	Same	LP	Same. Note that there is more bone at the periphery.
	15	Same	HP	Chondroma. Lobule of somewhat hypercellular cartilage without significant atypia. Note thin rim of pink bone containing blood vessels. Lack of significant numbers of binucleate chondrocytes and lack of atypia (as well as the location and size clinically) help in differentiating this lesion from chondrosarcoma.
	16	Bone	LP	Healing fracture. Note thick layer of periosteum, somewhat disorganized new bone where cortical bone should be, and cartilage and fibrous tissue intermixed with bone (callus).
	17	Bone	LP	Healing fracture. Note islands of necrotic bone (pink, irregular, and no nuclei), most of which has been resorbed, irregular trabeculae of woven bone, and fibrous tissue.
	18	Bone	HP	Healing fracture. This field has mostly woven bone and cellular fibrous tissue.
	19	Bone	HP	Healing fracture. Woven and some lamellar bone, cartilage and granulation tissue.
	20	Femur	X-ray of halved surgical specimen	Osteosarcoma. Destructive neoplasm with a variable appearance with lytic and osteoblastic areas, and extension into soft tissue. There is a sunburst pattern where new neoplastic bone spicules are oriented at right angles to the surface of the bone in one area of soft tissue extension. The opposite side shows an area of tumor extension which is non calcified.
	21	Femur	LP	Ostogenic sarcoma. Note the irregular, eosinophilic osteoid and very cellular tissue with unevenly distributed giant cells. (In giant cell tumor of bone, the giant cells would be evenly distributed.)
	22	Femur	MP	Osteogenic sarcoma. Markedly cellular, pleomorphic neoplasm producing osteoid.
	23	Femur	HP	Osteogenic sarcoma. Note hypercellularity and that the individual cells have hyperchromatic, enlarged nuclei that vary and are different from the nuclei in the giant cell. (In giant cell tumor there is nuclear identity between giant cells and mononuclear cells). Note the pink osteoid.