<prompt> Fallen fragment sign is seen inSimple bone cystOsteosarcomaAdamantinomaAneurysmal bone cyst  <response>: A Simple bone cyst?Fallen Fragment Sign:Small piece of bone settles to dependent portion of a Unicameral Bone Cyst from pathological fracture.Solitary Bone Cyst:Physical findings - Usually asymptomatic.Cyst lying adjacent to growth plate can lead to growth disturbances.X ray findings centrally located, lytic lesion:Expansion of the bone.Well marginated outline.Thinning of the cortex scallopingPathognomonic for a simple unicameral bone cyst following a pathological fracture.Fallen fragment sign:Periosteal surface is smooth.Loculated appearance is due to presence of ridges over inner surface of cyst.May be seen in other cystic lesions, e.g. eosinophilic granuloma.RADIOLOGICAL DIAGNOSTIC SIGNSHatchet signRecurrent anterior dislocation of shoulderMetacarpal sign presence of short 4th metacarpalTurners syndrome, Pseudohypoparathyroidism some Normal peopleSnow cap signSickle cell diseaseTrummerfeld sign seen inScurvy, Leukaemia Acute infection Congenital syphilisCorner sign of Park Pelkan signScurvyVacuum sign is seen inPerthes disease Degen. disease of spineWaldenstroms sign is seen inEarly Perthes dis. in Irritable Hip syndromeHalo sign of WimburgerCongenital Syphilis, ScurvyTram-track signAnkylosing spondylitisWimbergeris signCongenital syphilisFallen fragment signUnicameral bone cystBeheaded Scottish terrier signSpondylolisthesisOther OptionsOsteosarcoma:Most common malignant primary bone tumor in young adults children; 2nd MC prirnary malignant bone tumor after multiple myeloma.Neoplastic tissue is radiolucent, Periosteal reaction shows Codmans triangle, Zone of transformation is fairly large, sun-ray appearance is characteristic produced by thin radiopaque spicules of bone, radiating away from the cortex of the bone, large soft tissue swellingParosteal Sarcoma - Low grade malignancy, seen in older age group, bone forming tumour, shows osteolytic lesion with radiolucent line between the cortex bone the new bone forms in the soft tissue around it.Adamantinoma Malignant Angioblastoma locally aggressivemalignant lesion.Histo: pseudoepithelial cell masses with peripheral columnar cells in a palisade pattern with varying amounts of fibrous stroma; areas of squamoustubularalveolarvessel transformation; prominent vascularity; resembles ameloblastoma of the jaw.Location: middle 13 of tibia 90, fibula, ulna, carpals, metacarpals, humerus, shaft of femur eccentric round osteolytic lesion with sclerotic margin, may have additional foci in continuity with major lesion Characteristic may show mottled density bone expansion frequent often multiple.Prognosis: tendency to recur after local excision; after several recurrences pulmonary metastases may develop.Aneurysmal bone cyst expansile pathologically benign lytic lesion of bone containing thin-walled cystic cavities filled with chronic blood products; name derived from roentgen appearance purely lytic eccentric radiolucency.Location: a spine 12-30 with slight predilection for posterior elements; thoracic lumbar cervical spine 22; involvement of vertebral body 40-90; may involve two contiguous vertebrae 25.b long bones; eccentric in metaphysis of femur, tibia, humerus, fibula; pelvis aggressive expansile ballooning lesion of soap-bubble pattern thin internal trabeculations rapid progression within 6 weeks to 3 months.Sclerotic inner portion almost invisible thin cortex CT shows integrity tumor respects epiphyseal plate no periosteal reaction except when fractured. 