Paget's Disease of Bone

by Carlo Raj, MD

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    00:01 Paget’s Disease of Bone is our topic.

    00:05 Prevalence of the bone disease - United Kingdom, Australia, South Africa, US.

    00:12 And with Paget’s disease of the bone, fundamentally this picture pretty much tells you the story of Paget’s disease.

    00:20 The story… the story began with healthy osteoclast and as the day wore on and as the weeks wore on, years wore on, osteoclast… Mr, Osteoclast kept… kept getting tired and tired, tired until he pretty much died.

    00:37 Huh! So, osteoclast, initially there might be too much chaotic osteoclastic activity and functioning.

    00:45 Therefore, initially, you would expect there to be increased bone resorption, if you take a look at the X-ray here.

    00:52 And on your left, you’ll notice that the bone appears quite lucent.

    00:56 That’s because of increased bone resorption.

    00:59 Keep that in mind.

    01:00 So, therefore, the patient initially might have hypercalcaemia.

    01:04 The story of osteoclastic activity continues and he starts or she starts, whatever, the cells start dying, starts burning out.

    01:15 So, if osteoclastic activity starts dying out, then please understand that there is going to be increase in bone activity.

    01:25 And with that increase bone activity, you are then going to have thickening of the bone as seen in the X-ray in the picture.

    01:32 So, therefore, the picture on the right shows you increased, thickened, white, opaque bone representing osteosclerosis.

    01:42 Now, what I haven’t shown you here is that there is a stage in between whereas I told you there is declining functioning of the osteoclast.

    01:52 So, initially, there was osteolytic lesion, then there will be as the osteoclast burning out a mosaic pattern, ultimately when we have thickening of the bone, it’s called osteosclerosis to the point where you might then cause compression of certain cranial nerves, for example, the vestibulocochlear.

    02:14 And with such nerves being compressed, you might have problems with hearing and maybe even ringing in the ears.

    02:20 Aetiology, to this day, really unclear, there are a few theories out there and usually, the patient that comes into you or when you read about this patient, you’ll hear that the patient is expressing that his or her hat size might be increasing.

    02:40 The pattern of bone involvement may involve one or many bones asymmetrically.

    02:45 Common sites include the pelvis, move a little bit higher… lumbar , even higher… skull and then in the pelvis region, you’re thinking about the femur, one of the major common sites.

    03:00 Most patients are asymptomatic with 90 percent, others have bone pain, skeletal deformity.

    03:06 This is what I was talking to you about earlier, particularly the frontal and the occiput, so the front and the back, either extremes of the skull, especially during the osteosclerotic phase, there might be enlargement of the skull, but then that means to you that the patient is expressing that his hat size is increasing.

    03:25 There might be bowed lower extremity, increased fracture risk… the more bone that you have doesn’t necessarily mean that what? It would be stronger.

    03:35 Remember, you have to have remodelling, the balance between osteoclasts and osteoblasts.

    03:40 That balance in Paget’s disease has been forever lost.

    03:44 So, therefore, femur, tibia, radius, extremely susceptible to pathologic fracture.

    03:52 Impingement syndrome, what does that mean? The last phase of Paget’s in which its osteosclerosis may then cause, as I was explaining earlier, compression of your cranial nerves.

    04:03 So, therefore, the vestibulocochlear might be affected in your ear, hearing loss and perhaps even vertigo.

    04:11 Late, uncommon manifestation… something that you want to keep in mind.

    04:17 So, let me give you some differentials or better yet, why don’t you give me some differentials in which the bone is becoming thicker.

    04:24 What is it called when you hear about marble bone disease that we talked about in ortho? That’s osteopetrosis.

    04:32 What if you had a patient that was older and now, you find an adenoma in the anterior pituitary and the patient is presenting as large hands, large tongue, hat size is increasing.

    04:47 You find that on laboratory studies that IGF1 is elevated.

    04:51 That’s acromegaly.

    04:53 Acromegaly, osteopetrosis, Paget’s disease… you can then expect there to be increased thickening of the bone, but each one will be a little bit different.

    05:03 How can you distinguish Paget’s disease from let’s say osteopetrosis? It’s easy with acromegaly, right? In acromegaly, what did I give you for laboratory test? Increased IGF1, hyperglycaemia, right, completely different presentation.

    05:20 Here, however, with Paget’s disease of the bone, we have high output congestive… high output heart failure from vascular shunts.

    05:27 In other words, it’s an AV malformations that you might find with Paget’s disease of the bone.

    05:33 Small percentage of your patients Paget’s disease of the bone may result in and develop osteosarcoma and immobilization results in hypocalcaemia, especially in Paget’s disease of the bone patients.

    05:47 Paget’s hip.

    05:49 If you take a look at the right side of this patient, then you’ll notice that it’s actually quite normal.

    05:59 The left aspect with all these arrows, these arrowheads that you’re seeing, the left side of this patient’s hip, you find there to be increased thickening.

    06:11 Thickened cortex, prominent trabeculae and could have lytic features.

    06:16 Remember, just because you have thickened bone doesn’t mean that it’s stronger bone.

    06:20 In fact, it’s increased prone or there’s increased tendency of fracture to take place.

    06:26 It may cause substantial pain, deformities and disabilities, especially in the elderly.

    06:32 It does not spread to other bones after those that are affected, so do not think about adjacent bones being affected, but the major bones that are affected… pelvis, the femur, the spine, the lumbar spine and maybe perhaps the skull; in the skull, the frontal and the occiput.

    06:50 Paget’s skull, enlargement of skull.

    06:54 Well, it looks like one huge cotton wool appearance.

    06:57 Hmm, the last time you’ve heard of cotton wool was in your fundoscopic examination when we talked about things like diabetes mellitus, so you know what cotton wool is and what it looks like.

    07:07 If it was looking like this, this is osteosclerosis, you can expect the hat size to be increasing and specifically in the occiput and the frontal bone region.

    07:17 Remember also please, because of increased thickness, there might be compression of the cranial nerve such as the 8th cranial nerve resulting with hearing loss and such and even maybe perhaps vertigo.

    07:29 Evaluation… lab studies isolated with now the alk-phos here is going to be incredibly elevated.

    07:37 That is the-one of the hallmark findings of Paget’s disease of the bone.

    07:40 You would never expect such an increase with acromegaly and with the osteopetrosis, once again, I’ve given you enough clues here that without a doubt you know that your patient has Paget’s disease of the bone such as your AV malformation, such as the tendency of developing osteosarcoma and the fact that the alk-phos or alkaline phosphatase is elevated.

    08:02 Look at this, greater than 500 units per litre.

    08:05 The plain film can reveal the three phases of the disease.

    08:08 Early on, it looks like osteoporosis.

    08:11 Keep that as a differential whenever you deal with bone disease, especially with Paget’s disease and osteoporosis.

    08:20 Osteoporosis is completely different, different presentation, maybe a female, post-menopausal.

    08:27 Later on, you get mixing.

    08:28 Who’s dying in the meantime? In other words, which osteo cell is burning out? The osteoclast.

    08:38 Initially, there is too much activity.

    08:40 Next, as it starts declining, there might be a mix between osteoclast, osteoblast, you call that a mosaic pattern and finally, third phase would be your sclerosis with cortical thickening, that I talked to you about earlier.

    08:52 The bone scan, most sensitive test, can reveal areas of increased uptake.

    08:58 And migratory lesions should call a diagnosis of Paget’s in to question.

    09:02 Evaluate for alternative such as metastasis to the bone.

    09:06 Paget’s disease of bone.

    09:11 Management, symptomatic patient evolve… involving the axial skeleton, weight-bearing bones; analgesics for the pain.

    09:20 Remember, the Paget’s disease of bone can be treated not cured, managed maybe perhaps with bisphosphonates.

    09:27 Bisphosphonate therapy, first line of the severe disease.

    09:32 Oral agents, these includes your risedronate and alendronate.

    09:37 Remember that alendronate could also be used for osteoporosis.

    09:42 The IV agents include pamidronate and zolendronate.

    09:46 Oral agents such as alendronate is important and we have IV agents such as pamidronate, that is important.

    09:55 Paget’s disease can monitor disease activity with alk-phos in urine N-telopeptide.

    09:59 Remember, once again, Paget’s disease of the bone the major significant increase would be alk-phos… 500 is the magic number.

    About the Lecture

    The lecture Paget's Disease of Bone by Carlo Raj, MD is from the course Bone Disease.

    Included Quiz Questions

    1. Dysfunctional osteoclast activity
    2. Chaotic osteoblastic activity
    3. Osteosarcoma
    4. Hypercalcemia
    5. Disordered alkaline phosphatase secretion
    1. Increasing height
    2. Enlarged frontal bone
    3. Bowed legs
    4. Pathologic fracture
    5. Cranial nerve impingement
    1. Cotton wool appearance
    2. Spread from skull to other bones
    3. Osteosarcoma
    4. Crew cut sign
    5. Decreasing hat size
    1. Osteolytic, mixed sclerosis and osteolytic, sclerosis
    2. Osteolytic, sclerosis, mixed sclerosis and osteolytic
    3. Osteolytic, sclerosis, ostelytic
    4. Sclerosis, mixed sclerosis and osteolytic, osteolytic
    5. Sclerosis, osteolytic, sclerosis
    1. Isolated alkaline phosphatase elevation
    2. Increased GH accompanied by elevated alkaline phosphatase
    3. Hypercalcemia and hypophosphatemia
    4. Decreased PTH, increased alkaline phosphatase
    5. Hypocalcemia and decreased alkaline phosphatase

    Author of lecture Paget's Disease of Bone

     Carlo Raj, MD

    Carlo Raj, MD

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