ABSTRACT
Cavernous hemangiomas/venous malformations
vening stroma, luminal thrombi, papillary endothelial hyperplasia (Masson lesion)
Gorham-Stout disease
proliferation of lymphatic vessels in bones leading to bone loss
FIBROUS SPINDLE CELL TUMORS OF BONE
Non-ossifying fibroma
demarcated ●● Bland uniform spindle cell proliferation,
interspersed giant cells, xanthomatous histiocytes
Desmoplastic fibroma
●● Similar to intraosseous desmoid-type fibromatosis
genized stroma, mitotic figures ●● High recurrence rate
Myofibromas
Cranial fasciitis
●● Fibroproliferative lesion resembling nodular fasciitis
●● Local growth erodes inner and outer table of skull
Congenital pseudoarthrosis
Fibrosarcoma
variant of osteosarcoma
Adamantinoma
●● Anterior diaphysis of tibia, well-circumscribed lesion
plasia ●● Bland spindle cell stroma, trabeculae of
woven bone and clusters of bland epithelial cells with peripheral palisading
●● Osteoblastic lining seen around bony trabeculae
basaloid, squamoid, pseudoglandular cells in myxoid stroma, may metastasize
ROUND CELL NEOPLASMS
Ewing sarcoma/primitive neuroectodermal tumor (PNET)
●● Second-most common pediatric malignant bone tumor
●● Imaging: Intramedullary, diaphyseal/ metadiaphyseal
with hyperchromatic nuclei, vacuolated to clear cytoplasm (glycogen)
●● Stain positively with PAS, CK, vimentin, CD99 (membranous), caveolin, FLI-1
Melanotic neuroectodermal tumor of infancy
●● Head and neck region: Maxilla, mandible, skull, brain/meninges
●● Larger epithelioid cells; glandular architecture, pigmented, positive for HMB45
●● Smaller cells; primitive, positive for neuroendocrine markers
Large B cell lymphoma
Langerhans cell histiocytosis (LCH)
●● Cells have abundant eosinophilic cytoplasm, folded nucleus, no processes
●● Infiltrate of Langerhans cells, eosinophils, Charcot-Leyden crystals, giant cells
disease ●● Acute disseminated LCH: Letterer-Siwe
disease
Chordoma
notochord ●● Cords and lobules of physaliferous cells
(vacuolated, bubbly cytoplasm) in fibromyxoid stroma
●● Stain positive for S100, CK, vimentin, EMA
OSTEOMYELITIS
●● Acute (neutrophils), subacute (mixture of neutrophils, lymphocytes, and plasma cells), chronic (lymphocytes, plasma cells, and macrophages)
●● Necrotic bone (sequestrum) and new bone formation (involucrum)
Acute osteomyelitis
●● Bacterial infection (Staphylococcus aureus); methicillin-resistant S. aureus (MRSA) or methicillin sensitive
●● In children with sickle cell disease = Salmonella
●● Tuberculous osteomyelitis is hematogenous, anterior portion of vertebral body (caseating granulomas)
●● Non-tuberculous mycobacterial infection in immunocompromised children (cystic fibrosis)
Subacute osteomyelitis
●● Brodie abscess (lytic lesion surrounded by osteosclerosis)
NON-BACTERIAL OSTEITIS
●● Auto-inflammatory disorder, chronic recurrent multifocal osteomyelitis
bony trabeculae, mosaic lines ●● Marrow fibrosis, chronic inflammation
ROSAI-DORFMAN DISEASE
●● Emperipolesis, background contains plasma cells, eosinophils, and histiocytes
INFANTILE CORTICAL HYPEROSTOSIS
condition ●● Soft-tissue swelling, inflammation, self-
limited course ●● Subperiosteal new bone formation, struc-
tural loss of cortical bone
OSTEONECROSIS
hemoglobinopathies (sickle cell disease) ●● Osteonecrosis of femoral head; seen in Legg-
Calvé-Perthes disease and Gaucher disease
●● Involved by infectious, metabolic, or autoimmune conditions
CHRONIC SYNOVITIS
●● Diffuse/nodular infiltrate of lymphocytes, plasma cells, mast cells
●● Hyperplasia of synovial cell lining, papillary architecture
Juvenile rheumatoid arthritis
large joints ●● Papillary synovial hyperplasia, lympho-
plasmacytic infiltrate, lymphoid follicles and germinal centers, multinucleated giant cells, fibrin and hemosiderin
HEMOPHILIC ARTHROPATHY
●● When factor VIII and IX levels <1% of normal
●● Infiltrates of lymphocytes, histiocytes, prominent hemosiderin deposits (synovial lining cells and histiocytes)
GRANULOMATOUS SYNOVITIS
HISTIOCYTIC SYNOVITIS
●● CD68 positive multinucleated giant cells and foamy macrophages
●● Non-tuberculous mycobacterial synovitis, arthropathy
TUMEFACTIVE LESIONS
●● Synovial chondromatosis, synovial lipomatosis, pigmented villonodular synovitis, giant cell tumor of tendon sheath, ganglion cyst
OSTEOARTHROPATHY
bolic disorder, osteonecrosis, abnormal skeletal development
