First reported thoroughly as a discrete entity by Sir James Paget in 1876, this is a bone lesion of unknown etiology characterized by a profound increase in both bone resorption and new bone formation resulting in simultaneous mixtures of lytic and sclerotic processes, initiating as a localized condition but often terminating as a widespread state.
The clinical, symptomatic form of the disease is certainly one of older people, most commonly over age 60 years and the prevalence increases with age. However this is often preceded by a decades-long asymptomatic period during which it is found serendipitously usually by a radiologic study carried out for some other reason. Overall it is found in 2-3 % of adults over 40 years (Krane, 1991:1937). Nevertheless, geographic prevalence rates vary greatly with higher frequencies present in parts of England, Europe, Australia and New Zealand, but rates less than 1 % have been reported from Scandinavia, African Blacks and India (Altman, 1993). Its cause is unknown, though a pattern suggestive of autosomal dominance has been found in about 15 % of the cases. A viral origin (measles? respiratory syncytial virus?) has been suspected on the basis of some morphologic and serologic findings but no unequivocal evidence for such a conclusion has emerged.
About 80 % of individuals with Paget's disease of bone in a radiographically surveyed adult population are without symptoms. In the remainder, bone pain is the usual feature leading them to seek medical aid. Predominantly lytic lesions are more apt to be painful than the densely sclerotic ones. During the period of greatest activity the affected area is often palpably warm, probably because of the up to 20-fold increase in blood flow. Eventually compressive changes resulting from thickening of the cranium by new bone formation can produce dysfunction of cranial nerves especially near the skull base where even the brain stem can be compressed, and cord compression can occur due to vertebral involvement (Krane, 1991:1938). The vault bones can thicken sufficiently to compress the cerebral hemispheres, producing a melange of motor or behavioral symptoms. While high serum alkaline phosphatase levels reflect the new bone formation, most afflicted persons have a normal serum calcium level. Eventually widespread disease may become incapacitating.
The alterations in the individual bones described below can produce certain characteristic effects. These include a moderate kyphosis that is due principally to vertebral body collapse in the lower spine, though in some individuals long bone leg fractures and bowing can also contribute to the shorter stature. Increased cranial blood flow includes the external carotid branches, producing bulging subcutaneous scalp arteries and veins. Frontal area bossing can be prominent. Altman (1993) has characterized the constellation of such effects in advanced stages of this condition as resembling a simian posture.
The frequency of individual bone involvement in decreasing order is pelvis, femur, skull, tibia, lumbar spine, dorsal spine, clavicles and ribs (Krane, 1993: 1938).
The initial, predominantly lytic phase causes a localized region of radiolucency known as ‘osteoporosis circumscripta’. Such an area grossly reveals a loss of trabeculae, though even at that stage the individual, surviving trabeculae already commonly are thickened by new bone formation. In addition both the inner and outer tables can be thinned to the point of difficult radiological recognition. Progression into a mixed and then predominantly sclerotic phase produces new bone at the inner and outer tables and eventually within the diploe as well (Figs. 15.1, 15.2, 15.3 & 15.4). During this phase of many years, new bone production and resorption occur simultaneously, though the degree of each varies from one area to the other. Jaffe (1972:250) emphasizes the enormous irregularity in radiodensity this produces and defines the radiologic picture of the lesions during this mixed phase as a ‘cotton wool’ appearance (Fig. 15.5). He likens the new bone to the granular structure reminiscent of pumice, and also notes that the eventual skull thickness usually does not exceed 2-3 cm (though extreme cases of twice that value have been reported). In addition, while facial bones are usually spared, when they do become enlarged in the late, predominantly sclerotic phase a distortion not unlike leontiasis ossea will result (Jaffe, 1972:250; Ortner & Putschar, 1985:312).
The lower end of the spine is most frequently involved and in a characteristic manner. All portions of the vertebra are affected, though the changes in the vertebral body are most apparent. There the periphery of the vertebral body's cancellous bone becomes most dense, often finely granular, while its central area is occupied by much fewer but thicker trabeculae. These localized differences become quite apparent radiologically Weight-bearing may cause the central portion of the body to yield and become compressed. New bone formation on the horizontal surface may widen the vertebra and cause vertebral fusion if the disc degenerates.
The pelvic changes parallel those in the skull but usually do not achieve a similar degree of thickening.
The spongiosa at either end of a long bone is usually the initial area of involvement by the lytic process (Fig. 15.6) which then progresses toward the other end with a V-shaped leading edge, trailed by denser bone in the sclerotic phase (Krane, 1991:1939). The cortex becomes thickened, though the medullary cavity is retained (Fig. 15.7). New bone is deposited preferentially on the concave surfaces, causing anterolateral bowing of the femur and lateral tibia bowing. Fissure-like stress fractures (infractions) are common. In addition, the newly-formed bone is lamellar, does not remodel in response to stress-produced effects and therefore does not have the strength of normal bone. The result is a vulnerability to complete, usually transverse, fractures that heal well but slowly (Fig. 15.8). In antiquity malalignment must have been common, contributing further to short stature.
Development of osteogenic sarcoma in an active lesion is the complication of greatest concern. It occurs in about 2—3 % of the cases, and is believed to arise from the fibrocytes that commonly occupy the space between trabeculae in involved areas. It is a devastating development and usually causes death from lung metastases within 2 years. Jaffe (1972:267) writes that he has never seen a person with Paget's disease survive 5 years after the diagnosis of osteogenic sarcoma.
The paucity of archaeological case reports is usually explained by the late age at which the disease becomes manifest clinically. However, as noted above, a large fraction of the cases have asymptomatic but radiologically evident single lesions that may begin as early as 40 years of age. This certainly overlaps with the ages examined by paleopathologists. If the current prevalence of at least 1 % of the population was similar in antiquity, then the dearth of case reports more probably reflects the fact that X-raying normal-appearing ancient bones is not yet a universal practice.
No doubt the earliest suggestion of Paget's disease in an archaeological bone is that by Palés (1929:263-7) involving a French Neolithic femur. Ortner & Putschar (1985:315) regard this as a possible candidate for such a diagnosis but no histopathological studies have been performed on it. The exceedingly rapid bone resorption and production in Paget's disease results in a cement line pattern of architectural disarray producing an irregular, mosaic structure. It requires no more than the viewing of a histologic bone section to identify this highly distinctive appearance if the specimen has maintained sufficient postmortem integrity. Today a reader can expect reports of Paget's disease of bone in an archaeological specimen to be accompanied by a description and photomicrograph of such a section's appearance. To date this has not been carried out on this Neolithic specimen.
Saul et al. (1981) describe a partial Maya skeleton from Belize (A.D. 800-1000) including a skull, two humeri and a clavicle whose changes suggest Paget's disease. Unfortunately we have available only an abstract for the paper presented at a conference but he reports that ‘preliminary histologic studies… support the strong possibility…’ of Paget's disease. An Anglo-Saxon burial from about A.D. 950 was found to have abnormalities compatible with Paget's disease in most of the skeleton of an elderly male from an English site (Wells & Woodhouse, 1975). Morphologically and radiologically the changes appear consistent with Paget's disease but unfortunately bone architectural preservation was insufficient to permit histological confirmation. Five cases from the central U.S.A. region reported by Denninger (1933) and two by Fisher (1935) as examples of Paget's disease have been reevaluated (Cook, 1980) and felt to be representative of treponematosis. An adult male skeleton from Norwich prior to A.D. 1468 may be an example of Paget's disease (Stirland, 1990). In addition two medieval skeletons (one an isolated sacrum) demonstrated both gross and histologic changes characteristic of Paget's disease, and the authors (Aaron et al, 1992) add that theirs may be the first example documented histologically
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What Is It? Bones in your body continuously break down and form again in a natural and tightly balanced process called bone remodeling. This bon
Definition, epidemiology, and etiology First reported thoroughly as a discrete entity by Sir James Paget in 1876, this is a bone lesion of unknow