Bombay Hospital Journal, Vol. 54, No. 2, 2012

Dept. of Nuclear Medicine and PET, Bombay Hospital and Medical Research Centre, 12, Marine Lines, Mumbai 400 020.

Unique Scintigraphic Features of Diffuse Idiopathic Skeletal Hyperostosis (DISH) on 99mTc-MDP Bone Scan

Pallavi Patil, Sunita Tarsarya Sonavane, Amrita Lahoti, Roshni Bhandary, Rajnath Jaiswar, Chanchala Kale

Introduction

ISH is diagnosed when ossification of Dthe anterolateral aspect of the

anterior longitudinal ligament is present

on at least four contiguous spinal levels

without involvement of the intervertebral

disk space and/or apophyseal (facet) 2joints. The disease can manifest itself also

at extraspinal locations leading to

peripheral entheseal ossification and bony 3,4spurs.

Case Report

A 61 years old gentleman, a known case of DISH

and recently diagnosed with adenocarcinoma of left

lung with mediastinal adenopathy complaining of

dull aching pain in the mid-dorsal region was referred

to our department for a bone scan to rule out skeletal

metastases. There is no history of trauma to the back.

Lateral view radiograph of the thoracic spine revealed

osteophytes present at the anterior margin of the D 6

to D vertebral bodies with normal intervertebral 10

discs and no evidence of lytic or sclerotic lesions in

the vertebrae. Ossification of the anterior

longitudinal ligament at multiple thoracic levels,

except for the part where the aorta is located,

confirmed the diagnosis DISH. In this individual the

CT scan of chest when performed for evaluation of

primary tumour left lung upper lobe mass, which

additionally revealed ossification of the ligamentum

flavum and partial ossification of the interspinal

ligament and supraspinal ligament. No other signs of

spinal degenerative changes such as intervertebral or

apophyseal joint space narrowing were observed. The

patient had no extraspinal manifestations of DISH.

Wholebody bone multiple planar static images were

obtained 3 hr after intravenous administration of 20 99mmCi (740 MBq) Tc-MDP. Images (preset counts of

700 Kcts) were made in the anterior and posterior

views with a Hawkeye GE millennium VG dual head

digital gamma camera equipped with a low-energy,

high-resolution collimator. The planar whole body

anterior and posterior views (fig. 1), static oblique

Fig. 1: Whole body planar anterior and posterior

images obtained 3 hrs after the injection of the

radioisotope reveals no definite scintigraphic

evidence of skeletal metastasis. Moderately increased

osteoblastic activity seen involving D6 and D7 right

paravertebral region, in view of the clinical history of

DISH is likely to represent benign degenerative

changes (osteophytes).

Abstract

Diffuse idiopathic skeletal hyperostosis (DISH) is a common but often unrecognised 1systemic disorder observed mainly in the elderly. All papers pertinent to DISH

5demonstrate a consistent and marked increase of the disease with advancing age .

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Bombay Hospital Journal, Vol. 54, No. 2, 2012

chest images (fig. 2) revealed no definite scintigraphic

evidence of skeletal metastasis. Moderately increased

osteoblastic activity seen in the right paravertebral

region in view of the clinical history of DISH is likely to

represent ben ign degenerat i ve changes

(osteophytes).

In conclusion, DISH may actually be a clinically

relevant condition although presumably only so

when the more advanced stages of the disease have

been reached.

Fig. 2: Static oblique chest images revealed

moderately increased osteoblastic activity seen

involving the D6 and D7 right paravertebral region.

Discussion

D i f f u s e i d i o p a t h i c s k e l e t a l

h y p e r o s t o s i s ( D I S H ) i s a

spondyloarthropathy also known as

Forestier's disease and ankylosing

hyperostosis. It is a noninflammatory

disease, with the principal manifestation

being calcification and ossification of

spinal ligaments and the regions where

tendons and ligaments attach to bone

(entheses). The most common abnormality

is unilateral calcification seen on one side 6,7of the thoracic spine. The exact cause is

unknown. It can be present as a

radiological abnormality, without any

symptoms. The usual complaint is with

thoracic spine pain. This occurs in around

80% of patients. Morning stiffness is also 8,9noticed in almost two thirds of patients.

Diffuse idiopathic skeletal hyperostosis

(DISH) describes a phenomenon

characterised by a tendency toward

ossification of ligaments. It most 10characteristically affects the spine.

Ossification of the longitudinal ligaments

(especially the anterior ligaments) of the

spine produces a tortuous paravertebral

mass anterior to and distinct (at least 11radiologically) from the vertebral bodies.

Grossly, the appearance is that of candle

wax dripping down the spine. While the

thoracic anterior longitudinal ligament is

ossified, the areas of ossification often

meet without fusion. Pathophysiology of

diffuse idiopathic skeletal hyperostosis

(DISH) is characterised by a tendency

toward ossification of ligament, tendon, 12and joint capsule (enthesial) insertions.

DISH is a completely asymptomatic

phenomenon; no alterations are

detectable based on history or through

physical examination. The features used 1 3to diagnose DISH are f lowing

calcifications and ossifications along the

anterolateral aspect of at least 4

contiguous vertebral bodies, with or

without osteophytes. Preservation of disc

height in the involved areas and an

absence of excessive disc disease. Absence

of bony ankylosis of facet joints and

absence of sacroiliac erosion, sclerosis, or

bony fusion, although narrowing and 14sclerosis of facet joints are acceptable.

The hallmark of DISH is ossification

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Bombay Hospital Journal, Vol. 54, No. 2, 2012

occurring along the anterior aspect of the

vertebral bodies but remaining separate

from the vertebrae. Osteophytes of

degenerative spinal disease usually occur

along the anterolateral aspect. The

location of the ossification distinguishes

DISH from ossification of the posterior 1 5l ong i tud ina l l i gament (OPLL ) .

Omnipresent degenerative osteophytes

represent the most common finding that

mimics DISH; however, DISH is defined by

the strict criteria of anterior location and

the bridging involvement of 4 contiguous

vertebral bodies (3 intervertebral disc

spaces). DISH and ankylosing spondylitis

differ in their age of onset. Unlike

ankylosing spondylitis, DISH does not

involve the sacroiliac joint. DISH is also

distinct from marginal osteophytes that

form in response to degenerative disc

disease. Lower thoracic spine involvement

is typical of DISH, but the lumbar and

cervical spine can also be affected. The left

side of the spine is typically spared or less

involved, which is probably attributable to

the pulsating aorta. Preferred examination

is radiography of the thoracic and lumbar

spine usually is sufficient for diagnosing

D I S H . O c c a s i o n a l l y , c o m p u t e d

tomography (CT) scanning may be

performed to evaluate complications, such

as fracture, or symptoms caused by

pressure effects on the trachea,

oesophagus, and veins. CT scanning of the

spine is helpful and especially is aided by

coronal and sagittal reconstructions. Bone

scanning and magnetic resonance

imaging (MRI) do not play a significant role 13in the diagnosis of DISH. The differential

diagnosis includes ankylosing spondylitis,

neuropathic arthropathy (Charcot joint),

primary osteoarthritis, and psoriatic

arthritis.

In conclusion, regarding the presently

known clinical symptoms, the diagnosis

DISH should be considered in patients of

m i d d l e o r a d v a n c e d a g e w i t h

unexplainable back pain or peripheral

arthralgia and/or restricted motion and

should alert the physician for the presence

of fracture dislocations in DISH patients

complaining of back pain after relatively 16minor trauma.

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Dalcetrapib: turning the tide for CETP inhibition?

In the search for additional cardiovascular-risk lowering strategies on top of statins, raising highdensity lipoprotein cholesterol (HDL-C) is an attractive target.

Despite controversial data on the role of cholesteryl ester transfer protein (CETP) in atherosclerosis, the impressive increase in concentrations of HDL-C after CETP inhibition has raised expectations for drugs of the CETP inhibitor class. But the ILLUMINATE study was prematurely terminated in 2006 because of an increased cardiovascular event rate in patients receiving the CETP inhibitor torcetrapib, which led to a fall in the popularity of CETP inhibition as a therapeutic target, while also casting a broader shadow on the attractiveness of raising HDL-C concentrations.

In The Lancet, Zahi Fayad and colleagues report a randomised, placebo-controlled, phase 2b study in which the CETP inhibitor dalcetrapib was used to increase HDL-C concentrations in 130 patients with coronary heart disease or an equivalent cardiovascular risk.

Dalcetrapib given for 2 years increased HDL-C concentrations by 26.9%, (90% Cl 20.0-33.9%) without affecting those of low density lipoprotein cholesterol (LDL-C) and triglycerides,. No adverse effects on the arterial wall or blood pressure were recorded. In fact, dalcetrapib was associated with a reduction in carotid vessel wall inflammation at 6 months.

Notwithstanding the absence of harmful effects, the jury is still out on the clinical value of cardiovascular protection by dalcetrapib.

As we await the final verdict on dalcetrapib in 2013, when the DAL-OUTCOME study will provide data on cardiovascular endpoints in 15600 patients, the findings of Fayad and colleagues bring us one step higher on the ladder of CETP research, after its free fall since 2006.

E Stroes, D Wijk, The Lancet, 2011; 1529-1530Vol. 378,

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