This document provides an overview of imaging findings in Diffuse Idiopathic Skeletal Hyperostosis (DISH). It describes how DISH most commonly involves the thoracic spine and can also affect other areas of the spine and peripheral joints. Key radiographic features of DISH in the spine include flowing anterior and lateral ossification along vertebral bodies, osteophyte formation, and preserved disc height. Extraspinal manifestations involve enthesophytes and ligament ossification in areas like the pelvis, heels, and elbows. The document contrasts DISH with conditions like spondylosis deformans, ankylosing spondylitis, and psoriatic arthritis that can have similar radiographic appearances.

1. Imaging of
Diffuse Idiopathic Skeletal
Hyperostosis
(DISH)
19
Muhanna Kazempour MD

2. INTRODUCTION
 Diffuse idiopathic skeletal hyperostosis (DISH) is a condition characterised by
calcification and ossification of ligaments and entheses.
 The condition usually affects the axial skeleton, in particular, at the thoracic segment,
though also other portions of the spine are often involved.
 DISH often involves also peripheral tendinous and/or entheseal sites either alone, or in
association with the involvement of peripheral joints.
 DISH is a common disease of older persons. (mean age :seventh decade)
 DISH predominates in men (two thirds)

3. Symptoms and signs
 Recurrent Achilles tendinosis
 Recurrent “tennis elbow”
 Progressive restriction of ROM
 Palpable calcaneal enthesophytes
 Palpable olecranon enthesophytes
 Dysphagia
 Restricted motion after total joint replacement
➢ Stiffness, restricted motion, and tendinosis in these patients are consistent with the underlying
radiographic alterations.
➢ In general, the clinical findings are mild in comparison to the spectacular radiographic evidence of
the disease

4. Resnick Criteria
1. The presence of flowing calcification and ossification along the anterolateral aspect of at
least four contiguous Vertebral bodies
R/O spondylosis deformans
2. Relative preservation of intervertebral disc height in the involved vertebral segment and
the absence of extensive radiographic changes of “degenerative” disc disease
R/O intervertebral (osteo)chondrosis
3. The absence of apophyseal joint bony ankylosis and sacroiliac joint erosion, sclerosis, or
intra-articular osseous fusion.
➢ R/O ankylosing spondylitis

5. Common sites and Radiographic Abnormalities
➢ Spinal
✓ Thoracic
✓ Lumbar
✓ Cervical
•Anterolateral flowing ossification
•Bumpy spinal contour
•Radiolucent disc extension
•Radiolucent area beneath deposited bone
➢ Extraspinal
✓ Pelvis
✓ Heel , Foot
✓ Hand
✓ Elbow
✓ Knee
➢ Bony proliferation
➢ Ligament calcification, ossification
➢ Para-articular osteophytes

6. Thoracic Spine
➢ Such calcification and ossification are most apparent on lateral radiographs of the thoracic spine. (7th and 11th )
➢ In the initial stages of the disease, small bony areas in front of the disk space can be observed in the sagittal projection
➢ calcification and ossification appear along the anterolateral aspect of the vertebral bodies and continue across the
intervertebral disc spaces.
➢ In the following stages, enthesophytes do elongate (more common on right sides of the vertebral bodies.)
➢ The contour of the involved thoracic spine is generally irregular and bumpy; occasionally, examples of a smooth
“pseudospondylitic” pattern of ossification may be seen.
➢ linear radiolucency may be detected Between the newly formed bone and the anterior border of the vertebral body.
➢ Radiolucent areas within the ossified mass at the level of the intervertebral discs correspond to anterolateral extension
of disc material.
➢ Thoracic disc space narrowing is generally mild or absent
➢ Ankylosis is often incomplete.

7. Criteria for Early-Phase Diffuse Idiopathic Skeletal
score 0 : normal vertebral
bodies without formation
of new bone
score 1: anterior new
bone formation
score 2: near complete
bridging
score 3: complete
bridging

9. flowing anterior ossification (arrowhead) with a bumpy spinal contour
radiolucent disc extensions (d)
radiolucent area between the deposited bone and underlying vertebral bodes (lu).

10. anterior spinal ossification (arrowheads)
radiolucent disc extensions (d)
radiolucent areas (lu)
exaggerated anterior vertebral concavity (c)

11. The bumpy spinal contour (arrowheads)
anterior hyperostosis with radiolucent disc extensions (d)
linear radiolucent areas (lu)

12. Thick flowing ossification of the anterior lateral ligament

13. (A–C) Sagittal: CT scan images of anterior flowing osteophytes (arrows).
(D) Coronal: DISH of the thoracic spine (arrow)

14. Lumbar spine
➢ The upper lumbar segments are involved in a large percentage of cases.
➢ Radiographical abnormalities along the anterior aspect of the lumbar spine are similar to those of the
cervical spine.
➢ Unlike the thoracic spine, the flowing ossifications are equally frequent on the right and left sides of the
lumbar spine.
➢ Initially, hyperostosis is observed along the anterior aspect of the vertebral body.
➢ With progression, cloudlike increased bone density and pointed bony excrescences develop.
➢ Additional findings include radiolucent areas, and the rare occurrence of posterior outgrowths.
➢ One can observe ossifications of the spinous processes and of the interspinous ligaments.
➢ The narrowing of the intervertebral space is generally mild to moderate.
➢ Degenerative changes in apophyseal joints can occur in the lower lumbar spine and in the lumbosacral
junction
➢ spinal stenosis is not rare (Due to the hyperostosis)

15. B,
anterior linear ossification (arrowheads)
radiolucent areas, both beneath the deposited bone (lu)
A,
bony excrescences or osteophytes (e)
cortical hyperostosis (h)
radiolucent areas (lu).
Note the preservation of the height of the intervertebral discs.

16. (A) L3–L4 right-sided large bridging osteophyte (arrow).
(B-D) non-marginal osteophytes

17. CT scan image showing ossification of the anterior lateral ligament
separated from the vertebral body (arrow).

18. Cervical spine
➢ The hyperostotic process develops along the lower half of the anterior border of the vertebral body
(4th and 7th )
➢ morphological aspects are described appears as ‘falling drop’, ‘candle flame’, ‘parrot-beak’ image or
‘bridge’.
 The initial finding is hyperostosis of the cortex along the anterior surface of the vertebral body.
 Gradually, extend across the intervertebral disc space.(inferior lip of the vertebral body and extend
downward)
 Progressive bony deposition can be either smooth and homogeneous or bumpy and irregular.
 A flowing pattern of ossification is frequently interrupted by radiolucent disc extensions at the level of
the intervertebral disc.
 posterior vertebral abnormalities include: hyperostosis of the posterior aspect of the vertebra,
posterior spinal osteophytosis, and posterior longitudinal ligament calcification and ossification.
 Elongation of the styloid process at the base of the skull or calcification or ossification of the stylohyoid
ligament, or both.

19. B
A bony shield (large arrowhead).
small posterior osteophytes (small arrowhead)
A
cortical hyperostosis(h)
pointed excrescences(e)
radiolucent area (lu).

20. ossification of the posterior longitudinal ligament (arrows)
ossification of both stylohyoid ligaments (arrowheads).

21. (C) Thickening and ossification of
anterior longitudinal ligament
(arrow),
large enthesophytes
(blue arrow)
nuchal enthesopathy
(red arrow).
(D) Flowing thickened
anterior lateral
ligament (arrow).
(E) Patient with DISH and
swallowing difficulties (arrow).
(A) Anterior osteophyte

22. A) osteophyte (arrow).
B) ossification originating from the discal annulus fibrosus (dotted arrow)
B) space between the anterior longitudinal ligament and the vertebral body (arrow).
(C) large anterolateral osteophyte (arrow).

23. Extraspinal Abnormalities
OR
Peripheral joint involvement
 Typically, they have a bilateral and symmetrical distribution.
 Pelvis
 Heel
 Foot
 Elbow
 Hand, wrist
 Knee

24. pelvic
 bony proliferation or “whiskering,” ligament calcification and ossification, and para-articular osteophytes .
 Proliferation (whiskering) is seen at sites of ligament and tendon attachment to bone, particularly on the
iliac crest, ischial tuberosity, and trochanters.
 Ligament calcification and ossification occur in the iliolumbar and sacrotuberous ligaments.
 Paraarticular osteophytes are noted along the inferior aspect of the sacroiliac joint, lateral aspect of the acetabulum, and
superior pubic margins, where they produce para articular osseous bridging.
 The most specific abnormalities in DISH are calcification or ossification of ligaments and enthesophyte formation at
insertion sites.

25. B,
an osseous bridge extends across the symphysis pubis.
A,
iliolumbar ligament mineralization (arrowhead)
osseous proliferation or “whiskering” (white arrow)
irregular bony excrescences above the acetabulum
and from lesser trochanter (black arrows)

26. (C) Bilateral hip joints’ capsule ossification (full arrows).
Enthesopathies of
greater trochanter (full arrows),
lesser trochanter (dotted arrows),
left hip capsule and iliac bone (empty arrow).

27. (D) Enthesopathy of the greater trochanter and hip joint capsule
(full arrow).
Periostitis of the iliac and ischial bones (empty arrows).
(E,F) Trochanteric enthesopathies (arrows).

28. (C) Ossification of anterior lateral ligament
(full arrow) and
large ileum enthesopathy (dotted arrows).
(A) Anterior bridges with normal
sacroiliac joints (arrows).
(B) Enthesopathy of the great trochanters (arrows).

29. Enthesopathies in DISH
(A) Plantar enthesophyte (arrow) and ossification of the terminal portion of the Achilles tendon (dotted arrow).
(B) Large, bilateral Achilles (dotted arrows) and plantar enthesopathies (arrows).
(C) Achilles enthesopathy (dotted arrow). Calcaneal enthesophyte extending along the plantar fascia (arrows).

30. Enthesopathies in DISH
(D) Enthesopathy of the patellar ligament (arrows).
Calcification of the posterior knee capsule (dotted arrow)
(E) Talonavicular enthesopathy (arrow).
(F) Ossification of the hips’ joints capsules (dotted arrows).
Enthesopathy of the right greater trochanter and the iliac
bone margins (arrow).
(G) CT: enthesopathy of the left greater trochanter (arrow).

31. osseous excrescences (arrowheads)
dorsal bone outgrowths (open arrows)
irregularity and enlargement of the base of the fifth metatarsal bone
(solid arrow)
Heel :
Enthesophytes on the posterior and inferior surface of the calcaneus
(irregular, without adjacent reactive bone sclerosis or erosions)
Foot: Bony excrescences
dorsal surface of the talus, dorsal and medial regions of the tarsal navicular, lateral and plantar aspects of the cuboid,
and base of the fifth metatarsal bone.

32. Patellar abnormalities in DISH
Osseous proliferation of the anterior patellar surface, with excrescences
extending from its superior and inferior margins into the adjacent tendons
(arrows).

33. Elbow abnormalities in DISH
A large olecranon enthesophyte (arrowhead).

34. (A) enlargement of the base of the distal
phalanx (arrows).
joint space narrowing and new bone formation of
both thumbs’ interphalangeal joint and the second
left DIP joint.
Hypertrophic osteoarticular
changes in the interphalangeal
joints.
Joint space narrowing of the second and
third MCP joints with enlargements and
osteophytes of the third metacarpal head.

35. Joint space narrowing with exuberant
new bone formation (arrows).
Hypertrophic/hyperostotic
Heberden’s nodes.
Third MCP capsular ossification
(arrow).

36. (I) Exostosis of the acromion (full arrow).
(II) Remodelling of the mid/proximal clavicle (empty arrow).
Large osteophyte of the first metatarsal head (arrow).

37. (A) Chondrocalcinosis in a patient with
DISH (arrows).
(B) Elbow joint space narrowing
with a osteophyte (arrow).
(C) Elbow joint space narrowing
with capsular ossification
(arrows).

38. (D) Knee:
femoral condyle osteophyte (white arrow),
ossification of the patellar tendon (black arrow)
large enthesopathy of the tibial tuberosity (dotted arrow).

39. large osteophyte of the humeral head (white arrow)
acromioclavicular degenerative osteophytes (dotted arrow).

40. Fractures in DISH
(A) X-ray: percutaneous fixation T 7–T12.
(B) CT scan: hyperextension fracture of Th10 (arrow).
(C) CT scan (sagittal) of a patient with fracture of the pedicle of the lumbar vertebrae 2 (arrow).
(D) CT scan (transversal) of a patient with fracture of the pedicle of the lumbar vertebrae 2.

41. DIFFERENTIAL DIAGNOSIS of Spinal Abnormalities
➢ Spondylosis Deformans /Resnick Criteria 1
➢ Intervertebral (Osteo)Chondrosis/Resnick Criteria 2
➢ Ankylosing Spondylitis /Resnick Criteria 3
➢ Psoriatic arthritis
➢ Acromegaly
➢ Hypoparathyroidism
➢ Fluorosis
➢ Ochronosis
➢ Axial Neuropathic Osteoarthropathy.

43. Intervertebral (Osteo)Chondrosis
 Moderate to severe decrease in height of intervertebral discs ; vacuum phenomena
 Sclerosis of superior and inferior surfaces of Vertebral bodies

44. Spondylosis Deformans
➢ spinal osteophytosis
➢ The presence of ligamentous calcification or ossification, and the existence of a
proliferative enthesopathy generally distinguish DISH from typical spondylosis deformans.

45. Spondylosis Deformans

46. D) DISH
C) Intervertebral
osteochondrosis
B) Spondylosis deformans
A) Cervical disc osteochondrosis
and facet arthrosis

47. Ankylosing Spondylitis
❑ In AS, syndesmophytes are thin, vertical osseous bridges that extend from one
vertebral body to the next
❑ In DISH Outgrowths are broad and irregular and have an anterior distribution.
✓ AS : vertebral body osteitis ,subsequent erosion, reactive sclerosis along the
anterior corners of the vertebra; sacroiliac joint erosion, sclerosis, and intra-
articular bony ankylosis; and apophyseal joint ankylosis.
✓ These manifestations are absent in DISH.

48. Progression of radiographic deterioration in both
the cervical (A) and the lumbar (B) spine
in a patient with AS.
Progression of radiographic deterioration in both
the cervical (A) and the lumbar (B) spine
in a patient with DISH.

49. Psoriatic arthritis
(1) Outgrowths that may resemble the typical syndesmophytes of AS
(2) Asymmetrical osteophytes, or
(3) paravertebral ossification.

50. Psoriatic arthritis
bulky ossification
There are large, asymmetric osteophytes
(white arrow).
They are thicker than the syndesmophytes
of AS and their asymmetric distribution
should raise suspicion of psoriatic disease.

51. psoriatic arthritis with axial involvement ankylosing spondylitis
radiographic evidence of syndesmophytes is less common in PsA than in AS.
Spinal disease in PsA is more frequently unilateral, the syndesmophytes show a larger volume, do not
follow exactly the course of the anterior longitudinal ligament and do not appear in consecutive
vertebrae, as compared to AS

52. Acromegaly
• Periosteal new bone formation
• Osteophytes
• scalloping of the vertebral body
• increased intervertebral disc space height.

53. Acromegaly

54. ➢ Hypoparathyroidism
osteophytes and enthesophytes in the presence of a normal intervertebral disc
space.

55.  Fluorosis
 severe osteophytosis of the spine and ligament ossification, particularly ossification of the sacrotuberous ligament.
The short arrow shows osteosclerosis of the pelvis
and vertebral column. The long arrow
demonstrates calcification of the sacrotuberous
ligament.
osteosclerosis of the posterior
longitudinal ligament.

56. Ochronosis
 osteophytosis and anterior disc ossification.
 The presence of extensive disc calcification and vertebral body osteoporosis allows an
accurate diagnosis.

57. Axial Neuropathic Osteoarthropathy.
 syphilis, diabetes mellitus, and syringomyelia.
➢ The initial radiographic findings may simulate those of intervertebral (osteo)chondrosis,
with loss of intervertebral disc space and vertebral body marginal sclerosis.
➢ Progressive alterations are increasing sclerosis, subluxation, fragmentation, and bizarre
osteophytosis.

58. DIFFERENTIAL DIAGNOSIS OF Extraspinal Abnormalities
➢ Ankylosing Spondylitis
The abnormalities at sites of tendon and ligament attachment to bone resemble the hyperostosis observed in DISH.
osseous erosion and sclerosis are more prominent/ In DISH, proliferative changes are without signs of erosion or underlying bone
sclerosis
➢ Hypertrophic Osteoarthropathy
symmetrical periostitis / diaphyseal periostitis is not usually prominent in DISH.
➢ Hypervitaminosis A
periosteal reaction and no other bone abnormality.
➢ CPPD
tendon calcification resembles the findings of DISH.
chondrocalcinosis is characteristic
➢ X-Linked Hypophosphatemic Osteomalacia
enthesopathy , calcification of the joint capsules and tendinous and ligamentous insertions ( infrequent and mild )

59. DISH and AS
(A) hips with coarse capsular ossification (arrows) with grade 4 sacroiliitis (dotted arrows).
(B) coarse asymmetrical osteophytes (arrows) with grade 4 sacroiliitis (dotted arrows).
(C) anterior thick bridges and ossification of the anterior lateral ligament.
(D) erosive sacroiliitis with anterior osseous bridges (dotted arrows).

60.  (E) X-ray of the knee: patellar (dotted arrow) and tibial tuberosity enthesopathies (arrow).
 (F) X-ray of the cervical And (G) lumbar spine with thickening and ossification of anterior
longitudinal ligament (arrows) as well as MRI sacroiliac joint (T1 sequence) with partial
ankylosis (H, dotted arrows) in a patient with both diseases DISH and AS.