It is useful to define the overall extent and distribution of disease. Tc-99m-MDP is highly sensitive but not specific. Low signal intensity on both T1 and T2 images suggesting the presence of compact bone or fibrous tissue least common pattern: seen in late sclerotic stageįatty marrow signal is usually preserved in all sequences unless there is a complication 10. Relatively low T1 and high T2 signal alteration (also referred as a “speckled” appearance) second most common pattern: probably corresponds to granulation tissue, hypervascularity, and edema seen in early mixed active disease Several major patterns of involvement have been described 8,16:ĭominant signal intensity in Pagetic bone similar to that of fat most common pattern and probably corresponds to longstanding disease The overall signal characteristics are variable, likely reflecting the natural course of the disease process in different phases. In rare cases, the disease is isolated to the diaphysis, most commonly in the tibia, rather than subchondral bone, which can cause diagnostic confusion Long bonesīlade of grass or candle flame sign: begins as a subchondral area of lucency with advancing tip of V-shaped osteolysis, extending towards the diaphysis These findings are often asymmetric, and for some reason, are more commonly seen on the right side. Vertical trabecular thickening: coarser than the more delicate pattern seen in intraosseous hemangiomas with which it may be confusedĬortical thickening and sclerosis of the iliopectineal and ischiopubic lines results in the pelvic brim sign and leads to obliteration of Köhler's teardropĮnlargement of the pubic rami and ischium Squaring of vertebrae: on lateral radiographs, flattening of the normal concavity of the anterior margin of the vertebral body also adds to the rectangular appearance This is said to be a pathognomonic appearance 25 Picture frame sign: Paget disease of the spine frequently manifests with cortical thickening and sclerosis encasing the vertebral margins, which gives rise to this appearance on radiographs in mixed-phase disease Tam o' Shanter sign: platybasia and basilar invagination with the appearance of the skull falling over the facial bones, like a Tam o' Shanter hat this is said to be a pathognomonic appearance 25 Osteoporosis circumscripta: large, well-defined lytic lesions involving the inner aspect of the outer table of the skull (stage one) with a preserved inner table.Ĭotton wool appearance: mixed lytic and sclerotic lesions of the skull.ĭiploic widening: both inner and outer calvarial tables are involved, with the former usually more extensively affected Sclerotic changes occur much later in the disease process.Īdditional destructive features may become apparent if malignant transformation occurs. The early phase features osteolytic (lucent) regions which are later followed by coarsened trabeculae and bony enlargement. Plain radiographic and CT features will depend upon the phase of the disease. * pathognomonic signs 25 Plain radiograph / CT Jigsaw pattern bone or mosaic pattern bone There are many Paget disease-related signs, listed here and described in the modality-specific sections below 25: These stages correlate well with the imaging findings. Intermediate stage (active, mixed): osteoblastic as well as osteoclastic activity There are three classically described stages, which are part of a continuous spectrum 22:Įarly destructive stage (incipient active, lytic): predominated by osteoclastic activity Viral infection (paramyxovirus) 6 in association with genetic susceptibility has been postulated. The etiology is not entirely known, but it is a disease of osteoclasts. Polyostotic disease is more prevalent than monostotic type 1. The most frequent sites of involvement are: Signs and symptoms relating to complications (see below) Increased bone size: historically changing hat size was a giveaway Increased focal temperature due to bony hypervascularity (not fever) Localized pain and tenderness (most common symptom 24) The majority (approximately three-quarters) of patients are asymptomatic at the time of diagnosis, the diagnosis being an incidental finding on imaging 23. Involvement of multiple bones ( polyostotic) is more common than single or monostotic disease. It is also common in Australia, New Zealand, Western Europe, and the United States. Incidence can be considerably higher in the United Kingdom than in other countries 8. Paget disease of the bone is relatively common and can affect up to 4% of individuals over 40 and up to 11% over the age of 80 1. There may be a slight male predilection for Paget disease. Synonymous terms such as osteitis deformans, which was the name given by Paget himself to the disease, are of historical interest only. Paget disease of the bone is the most common formal name for the condition 24.
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