Cystic Lesions of Bone #1 cause of Rib lesions, mostly Ossifying Fibroma - most in FIBROUS LESIONS OF BONE lytic, well circuscribed face Fibrous dysplasia - NO peri- slowly expanding & assoc w ex- Cortical based fibrous dysplasia osteal rxn or pain unless fx trapleural mass w same ground glass appear- Fx frequent but no pseudoarthro- Regress w puberty ance sis, no ST component Malignant degeneration reported homogeneous 1-5cm lesions, Elongated Diaphyseal lesion w in <1% maxilla & frontal #1 "Ground Glass" matrix MRI - Hyper T2 unlike most fi- assoc w loosening of the teeth in centered in medullary cav, "al- brous processes mandible phabet soup" of woven bone Malig degen to Osteosarc poss, Pt <10yrs, vascularized fibrous lucent, sclerotic, expasnsile, esp w polyostotic form stroma like FD patchy, etc... MRI high T2 No alphabet soup of woven bone Monostotic - #1 presentation, McCune-Albright syn - polyos- prox femur 78%, ribs, skull totic fibrous dysplasia Osteofibrous Dysplasia - fi- if in pelvis it will also be in ipsilat Florid disseminated form, usually brous lesion of tibia & fibula in prox femur unilat, female>male child <5yrs Diaphyseal if mild case, rarely assoc w cafe au lait spots and present w unilat bowing & pain- affects spine precocious puberty less enlargement of the leg Polyostotic - lesions usually trabecula surrounded by osteo- larger, freq Cafe-Au-Lait Adamantinoma - appears simi- blasts, mixed lytic Diaphyseal le- "Sheperds Crook" femur & cystic lar, mid tibia and jaw only sion pelvic lesions assoc can appear aggressive, 30+ yrs, no osteoclasts as in fibrous dys- Skull base thickening, CN en- trauma often assoc plasia croachment, asym orbits may be assoc w osteofibrous Juvenile Adamantinoma - possi- involvement of spine & soft tis- dysplasia, 15% met to lungs ble assoc sue myxoma more common Congenital Multiple Fibroma- Desmoplastic Fibroma - aggre- its clinical pres - pain tosis - Infantile Fibromatosis sive expansile con tis lesion 50% can degenerate to chondro- ST fibromas diagnosed at birth, Tibia #1, 10-20y/o, most benign sarcoma, histo identical stabalize by 4mo, regress by or low grade malignancy Diaphyseal long bone lesions 2yrs resembles soft tissue desmoid, more likely to deg forms lytic lesion along metaphy- 50% recur P resection Surgically excise, Bx is not a re- sis of long bones, variable size NO ST mass, never metastisize liable way to DDx DDx Giant Cell, ABC or Fibrosarc Juvenile Fibroma - benign fi- Very vascular, not easily distin- Ollier's Dz - mult enchondromas, brous tumors, cause pressure guished from FD NO inc in malig deg erosions Predominate Unilat, punctate can be aggressive, high T2 in- calc remain distinctive tensity, freq recur after resection ENCHONDROMA Bizzarre bulbous expansions of Juvenile Aponeurotic Fibroma - Lucent defect w Ring & arc tubular bones early subset w fibrochondral matrix chondroid, 40-50 Columnar growth of cartilage- occurs in deep palmar facia of Metaphyseal, unilat & solitary, nous tissue from epi young males never epiphyseal Become more rounded w older ST mass over wrist w stippled NO periostitis, central, eccentric Pts, Pathog calc, bone errosion poss & expansile Longitudinal striation - poss in Cartilage formed bones only, NO long bone metaphysis Cortical Desmoid - Reactive re- skull lesions pair at site of musc insertion #1 cystic lesion of phalanges, but Maffucci's syn - mult enchon- freq at adductor tubercle, "Don't no calc here dromas, Inc malig deg Touch" lesion. Sim bone infarct but not well de- Hemangiomas assoc, phleboliths fined or serpiginous seen. Chondrosarcoma differs only in LANGERHANS CELL HISTIO- of benign polyostotic ticular nodular in lungs CYTOSIS - HISTIOCYTOSIS X Periostitis freq, usually thick, wavy, & uniform Letterer-Siwe - Acute Dissemi- Birbeck Bodies - inclusions Fever poss similating osteo- nated Histiocytosis, <1y/o seen in cells on EM myelits Fulminate - 95% die, often bone Penilaminar Organnels also as- Skull #1, Beveled NONSCLE- lesions don't form soc ROTIC edges Permeative pattern sim to Ew- 50% have skin, eye, respiratory Calverial in 40%, often isolated ings sarc possible. & fever w enlarged nodes parietal, mandible 20% pts >2yrs w no organ dysfxn present as painful enlarging skull OTHER CAUSES OF BENIGN have 90% 5yr survival mass, rarely into dura CYSTIC LESIONS with organ dysfxn about 40% 5yr hearing loss & otitis type sx if Osteoblastoma - rare, Giant os- survival temporal bone involved teiod osteoma, >2cm Tx - chemo reserved only for Vertebra Plana - often effect post Expansile bubbly lesion, Scle- most severe cases elements as well, neuro sx rare rotic margins poss, sim ABC can have speckled calc or even Eosinophilic Granuloma - Non- Hand-schuller - Chronic Dis- blastic in long bones disseminated form, Bone only seminated Histiocytosis, <5y/o freq in post spine, predominatly 90% occur from 5-15yrs, 95% Triad of destructive lesions, lytic here white, 2:1 male, 70% in flat exophthalmos & diabetes insip- 30% are vertebral, may cause bones, idus cord compression femur & humerus #1 long bones, D. Insipidus II' to hypothalmus Appendicular are lytic w NO soft 60% diaphyseal, rare in hands involvement, hyper T2 in pit stalk tissue mass central bony sequestrum like os- 90% have cranial involvement, teomylitis & fibrosarc poss 15% have classic triad Osteoid Osteoma - not tumor or Monostotic usually but #1 cause NO osteopenia or erosions, Re- infection, unkown etiology Cortically based sclerotic lesion CT, very vascular w nidus <2cm, pt under 30 DDx - Osteomyelitis is always #1 Solitary Bone Cyst - Must be Metaphyseal 75%, 2/3 around in sclerotic lesion w nidus central in a pt under 30 knee may resemble sequestrum, can simple or unicamiral cyst, ex- Medulary - nidus in medula or also mimic stress Fx cluded if not central joint less sclerosis seen, 20% 2/3 occur prox humerus, prox Intrarticular - mimics synovitis, Aneurysmal Bone Cyst - must femur #2, any bone poss Sclerotic, joint eff seen be expansile in pt under 30 NOT most commonly seen Periosteal - minimal sclerosis, Tibia #1, 30% occur in assoc w a around knee unlike others cortical scalloping & ST swelling primary neoplasm Metaphyseal, grows in from phy- Spine - prefers appendages, freq Diaphyseal but usually near end, sis, rarely epiphyseal cause of Scoliosis extend to metaphysis Fallen fragment sign is pathag- unilat pars Fx still a more freq Markedly destructive esp in pel- nomonic cause though vic bones Asymptomatic unless fx, triangu- Spontaneous regression, can have densly sclerotic border, lar in calcaneus Recur if packed NEVER seen over age 30 Fx freq too early Resection curative, recurrance Can sim Osteoblastoma due to incomplete resection Spine appendages often in- Hyperparathyroidism - Pain at night releived by aspirin volved, lg soft tissue mass HYPERcalemia, HYPOphos- NUCS - Double Density sign Present w pain, may follow phatemia caused by hot nidus truama Subperiosteal Resorbtion - radial Angio - Nidus is hypervascular, CT - can show multiple com- aspect of dist phalanx rapid washout partments, fluid-fluid levels in dist clavicles, med prox tibia, & MRI - shows nidus lying in region 30% sacroilliac joints of marrow edema Can show rim enhancement w osteopenia & cortical resorb of nidus enhances on both MRI & cent low atten long bones late Brown Tumors - flat bones & ribs MDP, only seen w 50% in I' HPT Chondromyxoid fibroma - men- #1, sim ABC, giant cell Phosphate retained, Ca+ low tion w nonossifying fibroma most assoc w I' form, must have (Normal Ca+ 8.4-10.2, phos can present w pain in any age, other HPT Sx as well 2.2-4.5) most in dist toe phalange Parathyroid Adenoma may cause Diaphyseal w subendosteal tracheal deviation Chondroblastoma - must be thickening & scalloping Tx of HPT - all sx resolve, brown Epiphyseal in a pt under 30 Usually NO chondroid matrix, NO tumors scleros, resorb Most occur at Knee, Calc fre- malig degen Calcitonin - has opposite effect quently seen Difficult to distinguish from chon- as Parathyroid Hormone 50% will have sm extention droblastoma histologically decreases bone resorbtion, inc across the epi to metaphy renal Ca+ clearance 70% assoc w periostitis in dia- Cystic Angiomatosis - rare, as- causes Hypophosphatemia & phymetaphyseal region adjacent soc w Osler-Weber-Rendu, asym Hypocalcemia Lytic & epiphyseal: 1) infection, when isolated 2) this, 3) giant cell mult complex cystic lesions any- II' Hyperparathyroidism - Renal EG and ABC also but very rare, where, may spontaneously re- Osteodystrophy, more common mets & myeloma over 40 gress Soft tissue calc, Chondrocalcino- consider subchondral cyst if joint 70% w viceral involvement have sis & Osteosclerosis MORE DJD assoc bad prognosis. common carpal, tarsal bones, and patella kidney can't hydroxylate 25- behave like epihysis hydroxy to 1,25- Apophysis (ligamentous attach- dihydroxycholecalciferol ment) is similar causes compensatory elev in MRI - often low T2 in child due to parathyroid hormone cellular nature Freq cause of "Super Scan" w RARE CAUSES OF BENIGN seen in 15% w multiple mye- Synovitis -benign synovial swel- LYTIC LESIONS loma, preserves joint space ling 1.Inclusion Cyst - follows osteopenia & rib lesions com- Subarticular erosions poss w trauma to dist digits mostly mon, NO subperiosteal resorb joint pain & swelling Epidermoid lines cyst walls Course trabeculation in hands Lg subchondral cysts w NO joint poss, sim SLE space narrowing typical 2.Glomus Tumor - ST mass w Protenacious deposits in heart & CALC NEVER SEEN, no os- destructive lesion, sharp margins