bone, joint, ST

this bone disease is porous bone with reduced mass from increased clast activity and decreased blast. microscopically there are thin trabecular plates with loss of interconnections

osteoporosis

this disease occurs in older people with increased clast activity with blast increased as well. there is a gain in bone mass but it is brittle. microscopically there is lamellar bone in a mosaic pattern

pagets disease

this acutely shows hemorrhage. chronic shows hematoma and fibrous tissue and then woven bone forming a bony callus. eventually the it is remodeled to the original contour of the bone

fracture

this is an ischemic geographic necrosis involving trabecular bone and marrow. dead bone shows empty lacunae with necrotic marrow adipocytes. there is a creeping substitution with new bone forming on dead fragments. the problem is collapse of subchondral bone leading to osteoarthritis

avascular necrosis

this is from bacterial infection with acute and chronic inflammation, bone necrosis, bone resorption. there is an ingrowth of fibrous tissue and reactive new bone formation at the periphery of the infected

osteomyelitis

this is a benign bone tumor often in the skull. microscopically appears as normal cortical bone. this tumor may impinge on other structures like cranial nerves

osteoma

this is a malignant tumor producing osteoid, is gritty gray and white grossly. microscopically shows coarse irregular lace like pattern of bone produced by malignant osteoblasts. primary mets to the lung

osteosarcoma

this disease is a benign cartilage tumor within the medullary cavity, most often in small bones of hands and feet, shows benign cartilage on micro with abundant blue-gray matrix. this can predispose to fracture

enchondroma

this is the most common benign bone tumor usually near joints. grossly is mushroom shaped. microscopically shows benign cartilage capped tumor attached to bone by bony stalk. the cartilage cap has underlying endochondral ossification

osteochondroma

this is a malignant tumor of cartilage. microscopically is hyper cellular with pleomorphic chondrocytes and permeation of trabecular bone (snakes through it). this occurs in middle aged-older patients in pelvis, femur, humerus, it is not sensitive to chemo.

chondrosarcoma

this is localized arrested development of bone, normal bone components but not organized into mature structures. causes pain, enlargement and path ex’s. typically younger people and has a ground glass appearance on imaging microscopically has curved trabeculae of WOVEN bone (c shaped, Chinese letters) in a background of fibrous tissue wth fibroblasts. LACKS OSTEOBLASTS

fibrous dysplasia

this is a benign. but locally aggressive neoplasm that is grossly red-brown in color. microscopically contains mononuclear and multinucleate giant cells which are osteoclasts. treated with currettage, occurs in young adults at end of long bones. the spindle cells in the background are the malignant cells

giant cell tumor of bone

this is a small round blue cell tumor in pediatric cases, typically receives neoadjuvant therapy, soft tan tumor in the medulla which invades the cortex. micro you see sheets of blue cells with scant cytoplasm

Ewing sarcoma

this is typically from breast, lung, thyroid, kidney, prostate (BLT kosher pickle), X-rays show mixed lytic and plastic bony reaction. can see epithelial cells which are round or polygonal with more cytoplasm and malignant features

metastatic carcinoma

this disease shows weakened articular cartilage due to increased water content. there are fibrillations and cracks of cartilage, erosion, fragments falling off, loose bodies, exposure of bone, bony cysts, bony sclerosis

osteoarthritis

this is an inflammatory process manifesting in the synovium with hyperplastic inflamed synovium with lymphoid aggregates and plasma cells with organizing fibrin on surface of synovium. a pannus forms which is synovium growing over articular cartilage and eroding it

rheumatoid arthritis

this is deposits of monosodium irate in soft tissue around joints which chalky white deposits. microscopically periarticular soft tissue shows areas of amorphous dissolved rate crystals, reactive fibroblasts, multinucleate giant cells, the crystals are needle shaped

gout

this is a small benign simple cyst near joint caused by cystic degeneration of connective tissue. fluid is similar to synovial fluid, no communication with joint space. microscopically is an open cystic space within unremarkable fibrous tissue, LACKS CELL LINING

ganglion

this is usually associated with tendon sheets on the finger, localized (nodular) and diffuse (villous) variants, grossly yellow-brown. micro has many macrophages and giant cells either hemosiderin. is benign

tenosynovial giant cell tumor

this a benign tumor of fat, grossly is smooth yellow fat. micro shot encapsulated benign mass of fat with normal looking adipocytes. usually subcutaneous

lipoma

this is a malignant tumor of fat, is the most common soft tissue sarcoma of adulthood which arises in deep tissues. micro shows lipoblasts which mimic fetal fat, round vacuoles of lipid indent the nucleus, some normal fat present, myxoid type has pale blue-gray mucus in the background which can have a chicken wire appearance. myxoid type is common in young adults

liposarcoma

this occurs in young adults deep in the dermis and grows rapidly. it is a cellular lesion with immature appearing fibroblasts, and a myxoid stroma

nodular fasciitis

this is a locally aggressive fibroblastic tumor of young adults arising in musculature. it is grossly white and firm and poorly demarcated. microscopically shows plump fibroblasts with dense collagen. tumor cant typically be resected due to irregular borders and local aggressiveness

deep seated fibromatosis

this us a malignant tumor of skeletal muscles, is the most common soft tissue sarcoma of childhood and adolescence, soft gray mass, cells vary from small and round to eosinophilic with striations. these cells mimic the embryogenesis of skeletal muscle-u can see the striations sometimes

rhabdomyosarcoma

this is a benign smooth muscle tumor often in uterus with intersecting bundles of eosinophilic spindle cells and cigar shaped nuclei

leiomyoma

this is a malignant tumor of smooth muscle cells in adults in deep soft tissue, shows intersecting bundles of pleomorphic eosinophilic spindle cells with cigar shaped nuclei and mitotic activity

leiomyosarcoma

this is a deep soft tissue tumor of young adults often near the knee joint. micro shows dense spindle cell growth pattern. biphasic can have small gland like formations and monophonic is all spindle cells. it is slow growing but can mets

synovial sarcoma

this is a deep soft tissue tumor of adults which is relatively common. micro shows aggressive sarcoma with bizarre pleomorphic cells and high mitotic rate. can see multilobated nuclei

undifferentiated pleomorphic sarcoma