Diffuse idiopathic skeletal hyperostosis (DISH): where we are now and where to go next

Challenges in the clinical diagnosis of psoriatic arthritis

Psoriatic arthritis (PsA) is a chronic heterogeneous inflammatory musculoskeletal disease. The non-specific and often subtle manifestations make early diagnosis and subsequent treatment challenging. In the absence of diagnostic criteria and biomarkers, the diagnosis is often delayed leading to poor long-term outcomes. In addition, the differential diagnosis of a patient presenting with arthritis in the setting of skin psoriasis is wide due to symptom overlap with many other diseases. Peripheral arthritis, dactylitis, enthesitis and axial arthritis are the 4 domains of musculoskeletal involvement in PsA and careful examination of each domain by a rheumatologist is the first step for a correct diagnosis. Other extra-musculoskeletal features such as the presence of uveitis, inflammatory bowel disease, nail psoriasis and elevated acute phase reactants aid in the diagnosis of PsA. Screening patients with skin psoriasis using validated questionnaires might help in early diagnosis especially when coupled with imaging.

Patients with ankylosing spondylitis suffering from AO Type B3 traumatic thoracolumbar fractures are associated with increased frailty and morbidity when compared with patients with diffuse idiopathic skeletal hyperostosis

Background

AO Type B3 hyperextension thoracolumbar fractures are the commonest fracture subtype in ankylosing spinal disorders. Although often considered together in spinal fractures, ankylosing spondylitis (AS) and diffuse idiopathic skeletal hyperostosis (DISH) are distinct spondyloarthropathies with different pathophysiology. Few studies have compared the two entities in the setting of traumatic thoracolumbar fractures. The authors compare demographic metrics, injury profile, clinical and radiographical outcomes between patients with AS and DISH in patients suffering from AO Type B3 traumatic thoracolumbar fractures.

Methods

From January 2008 to December 2018, a retrospective analysis of consecutive surgically-managed patients with AO Type B3 fractures was performed. Demographic metrics, co-morbidity [Charlson-comorbidity index, modified frailty index (mFI), etc.], injury profile (level of injury, mechanism of injury, etc.), clinical (postoperative complication, etc.) and radiographical variables were collected. Differences between patients with AS and DISH were compared.

Results

Fourteen patients were identified. All patients had AS (n=6) or DISH (n=8). The mean age was 72.8±10.2 years and 78.6% of patients were neurologically intact at presentation. Medical and/or surgical complications occurred in 10 of 14 (71.4%) patients. As compared to patients with DISH, patients with AS were more likely to have low falls as the injury mechanism [odds ratio (OR): 35.0, P=0.026], have higher mFI (OR: 30.6, P=0.015), and experience a higher number of postoperative complications per patient (AS: 1.8/patient vs. DISH: 0.5/patient, P=0.024).

Conclusions

In the setting of AO Type B3 fractures, patients with AS are more frail and have higher in-hospital morbidity compared to patients with DISH. Despite both pathologies being ankylosing in nature, further studies are required to fully understand the clinical differences between the two entities to enable clinicians to apply a more targeted and nuanced approach in managing fractures in ankylosing spinal disorders.

Diffuse idiopathic skeletal hyperostosis in a 33-year-old woman with PCOS and metabolic syndrome: a rare scenario

Diffuse idiopathic skeletal hyperostosis (DISH) is a common degenerative enthesopathy seen in the elderly with male preponderance. It is uncommon in patients before 50 years of age and is extremely rare in patients younger than 40 years. We report a case of 33-year-old unmarried woman who presented with inflammatory spinal pain and stiffness, limited chest expansion, decreased range of spinal motion and postural abnormalities, all of which suggested the diagnosis of ankylosing spondylitis, considering the patient's age. But, further evaluation led us to the final diagnosis of DISH with associated metabolic syndrome and polycystic ovarian syndrome (PCOS). To the best of our knowledge, our patient is the first reported case of DISH in a woman less than 40 years of age, and also the first case of DISH associated with PCOS and metabolic syndrome.

[Differential diagnosis of axial spondyloarthritis-axSpA mimics]

The classification of axial spondyloarthritis (axSpA) comprises the classical ankylosing spondylitis (AS), which is characterized by already existing structural changes in the sacroiliac joints, and the so-called non-radiographic axSpA (nr-axSpA), in which by definition such changes are not present. This distinction is based on the ASAS classification criteria for axSpA, which are however not suitable for a diagnosis. According to the current classification, spondyloarthritis (SpA) includes axSpA, which can be associated with psoriasis and/or chronic inflammatory bowel diseases (CED), such as Crohn's disease and ulcerative colitis, and peripheral SpA, which is further divided into SpA associated with psoriasis, partially synonymous with psoriatic arthritis (PsA), reactive SpA, partially synonymous with reactive arthritis (ReA) and SpA associated with CED, partially synonymous with arthritis associated with CED (e.g. Crohn's disease, ulcerative colitis) and peripheral undifferentiated SpA, which by definition is not associated with any of the above. In this article only the most important differential diagnoses are discussed, i. e. diffuse idiopathic skeletal hyperostosis (DISH), fractures and infections in the axial skeleton. In addition, the frequency of certain musculoskeletal findings in the normal population examined by magnetic resonance imaging (MRI) are also discussed.

Respiratory presentation of diffuse idiopathic skeletal hyperostosis (DISH): Management and review of the literature

Background: Diffuse idiopathic skeletal hyperostosis (DISH) is characterized by the ossification of entheses. When localized in the cervical paravertebral region, typical signs and symptoms include stiffness, pain, loss of range of motion, and difficulty swallowing. Clinical Presentation: The authors present two less typical respiratory manifestations of DISH due to cervical osteophytes protrusion and obstruction of the upper airway. The first patient was treated conservatively (application of CPAP during nighttime), while the second required emergency intubation and a combined ENT-neurosurgical operation for the removal of osteophytes. Clinical Relevance: Even though dysphagic symptoms are more frequent, DISH may be a cause of airway obstruction and should be included in the differential diagnosis of respiratory distress and OSA.

High prevalence of abnormalities on chest radiography in rheumatoid arthritis

INTRODUCTION

Chest radiography (CXR) is commonly performed in rheumatoid arthritis (RA), particularly for the diagnosis of pulmonary disease. However, other structures are visible on CXR, abnormalities of which may contribute to morbidity and early mortality. This study was undertaken to evaluate the extent of CXR abnormalities in RA patients.

METHODS

Consecutive out-patients meeting the 2010 ACR/EULAR classification criteria for RA were included. The most recent CXR was assessed by two independent reviewers. Abnormalities identified were recorded and compared to the formal CXR report. Predictors of abnormalities on CXR were assessed using chi-squared tests. SPSS 18.0 was used for statistical analysis.

RESULTS

One hundred and ninety-eight patients were included. Mean age was 62 years (range 18-90). One hundred and nine (55.1%) were current or ex-smokers. One hundred and fifty-six (79%) patients were seropositive and 123 (62.1%) had joint erosions. A recent CXR was available in 163 (82%) cases. Abnormalities were identified in 129 (79.1%). Ninety-seven (60%) had bony abnormalities. Seventy-one (43.6%) had pulmonary abnormalities; old tuberculosis in 34 (20.9%), hyperinflation in 24 (14.7%), interstitial changes in 20 (13.3%), nodules in 4 (2.4%), consolidation in 2 (1.2%), and pneumothorax in 1 (0.6%). Cardiomegaly was identified in 37 (22.7%) and aortic calcification in 24 (14.7%). Age (p = 0.001), male gender (p = 0.01), and seropositivity (p = 0.04) were significantly associated with lung abnormalities. Cardiomegaly was associated with hypertension (p = 0.012) and ischaemic heart disease (p = 0.018).

CONCLUSION

Abnormalities were identified in 79% of chest radiographs in RA patients. Sixty-six percent of these were not reported. Clinicians need to be aware of the need to check for abnormalities.Key Points• RA patients have a high prevalence of CXR abnormalities.• Many of these are of clinical significance.• Age, being male, and seropositivity were associated with lung abnormalities.

Criteria for Early-Phase Diffuse Idiopathic Skeletal Hyperostosis: Development and Validation

Background Diffuse idiopathic skeletal hyperostosis (DISH) is a condition characterized by the formation of new bone along the anterolateral spinal column at four adjacent vertebral bodies. Purpose To propose and validate criteria for the early phase of DISH by using CT data from two large-scale retrospective cohorts, each with 5-year follow-up. Materials and Methods For this retrospective study, CT data at baseline and follow-up in 1367 patients (cohort I) from 2004 to 2011 were evaluated by two observers to define no DISH, early-stage DISH, and definite DISH on the basis of interval development of consecutive complete or incomplete bone bridges. An independent group of 2267 participants from the COPDGene cohort from 2008 to 2016 was used to validate the early DISH criteria (cohort II). The sensitivity and specificity of early DISH criteria were based on findings in the last CT study as the reference standard by using a nested case-control design. κ Values were calculated between seven readers and with a 3-month interval for one reader. Results Cohort I consisted of 100% men, with a mean age of 60.0 years ± 5.6 (standard deviation) and a mean time between baseline and follow-up CT of 5.0 years ± 1.1. Cohort II consisted of 51% men, with a mean age of 59.9 years ± 8.6 and a mean time between baseline and follow-up CT of 5.4 years ± 0.5. In the derivation cohort, 55 patients comprised the early DISH group. Early DISH was defined as the presence of a spinal segment with a complete bone bridge with an adjacent segment of at least a near-complete bone bridge and another adjacent segment with at least the presence of newly formed bone or when three or more adjacent segments were recorded as showing a near-complete bone bridge. In the validation cohort, sensitivity for early DISH (vs no DISH) was 96% (99 of 103 participants; 95% confidence interval [CI]: 90%, 99%). The corresponding specificity was 83% (1695 of 2034 participants; 95% CI: 82%, 85%). The Fleiss κ for interrater reliability was 0.78 (95% CI: 0.77, 0.78), and the κ for intrarater reliability was 0.89 (95% CI: 0.82, 0.96). Conclusion Early diffuse idiopathic skeletal hyperostosis (DISH) criteria had high sensitivity and specificity for predicting the development of DISH. © RSNA, 2019 Online supplemental material is available for this article. See also the editorial by Block in this issue.

Ectopic spinal calcification associated with diffuse idiopathic skeletal hyperostosis (DISH): A quantitative micro-ct analysis

Diffuse idiopathic skeletal hyperostosis (DISH) is a non-inflammatory spondyloarthropathy identified radiographically by calcification of the ligaments and/or entheses along the anterolateral aspect of the vertebral column. The etiology and pathogenesis of calcifications are unknown, and the diagnosis of DISH is currently based on radiographic criteria associated with advanced disease. To characterize the features of calcifications associated with DISH, we used micro-computed tomographic imaging to evaluate a cohort of 19 human cadaveric vertebral columns. Fifty-three percent of the cohort (n = 10; 3 females, 7 males, mean age of death = 81 years, range 67-94) met the radiographic criteria for DISH, with calcification of four or more contiguous vertebral segments. In almost all cases, the lower thoracic regions (T8-12) were affected by calcifications, consisting primarily of large, horizontal outgrowths of bony material. In contrast, calcifications localized to the upper thoracic regions demonstrated variability in their presentation and were categorized as either "continuous vertical bands" or "discontinuous-patchy" lesions. In addition to the variable morphology of the calcifications, our analysis demonstrated remarkable heterogeneity in the densities of calcifications, ranging from internal components below the density of cortical bone to regions of hyper-dense material that exceeded cortical bone. These findings establish that the current radiographic criteria for DISH capture heterogeneous presentations of ectopic spine calcification that can be differentiated based on morphology and density. These findings may indicate a naturally heterogenous disease, potential stage(s) in the natural progression of DISH, or distinct pathologies of ectopic calcifications. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

Oropharyngeal dysphagia as an uncommon manifestation of an osteoarticular disease

We report a case of a 76-year-old Caucasian woman who was referred to our department due to progressive dysphagia. We performed a flexible nasofibrolaryngoscopy that demonstrated the presence of a non-pulsatile mass in the right posterior wall of the hypopharynx. Cervical CT scan revealed that the mass represented a bulging of the hypopharynx wall produced by osteophytes along the cervical segment (C3-C4 and C4-C5) of the rachis. The patient was successfully treated with conservative measures with progressive improvement of dysphagia. This case highlights that anterior cervical osteophytosis should be included in the differential diagnosis of oropharyngeal dysphagia.

Interobserver agreement using Schlapbach graded scale for diffuse idiopathic skeletal hyperostosis (DISH): can we reduce the cut-off point of vertebral affection?

Resnick-Niwayama criteria for diagnosing DISH depict an advanced stage, and a new reduced cut-off point with three contiguous vertebrae affected (two bone bridges) has been proposed. The aim has been to know the interobserver agreement by using a graded scale of DISH in which grade II matches with the new proposed cut-off point and grade III matches with the first criterion of Resnick-Niwayama. Males ≥ 50 years and postmenopausal women included in a population-based prospective study (the Camargo Cohort) were analyzed. Sample size was obtained according to an expected kappa of 0.95 and an accuracy of ± 8%. Three physicians applied independently Schlapbach graded scale (ranged from grade 0, no ossification, to grade III, ≥ 3 consecutive bone bridges) on the lateral radiographs of thoracic and lumbar spine of participants. We calculated inter- and intra-observer agreement and correlation. One hundred and fifty eight radiographs (79 patients, 68 ± 9 years) were assessed. Kappa values (95% confidence interval) for grades 0, I, II, and III were 0.63 (0.50-0.77), 0.49 (0.37-0.62), 0.32 (0.17-0.47), and 0.69 (0.60-0.77), respectively. Weighted kappa for the three pairs of raters were 0.87 (0.82-0.93), 0.84 (0.77-0.91), and 0.81 (0.72-0.90). Grade III was the image that generated greater agreement, while a significant decrease was noted in grade II, the new proposed criterion. The simultaneous presence of an incomplete DISH and osteoarthritis, in a thoracic spinal segment with peculiar anatomical characteristics (reduced disk spaces, kyphotic curve), is thought to be a major cause of variability in the results.

Retroodontoid Pseudotumor Related to Development of Myelopathy Secondary to Atlantoaxial Instability on Os Odontoideum

Retroodontoid pseudotumor (ROP) is a nonneoplasic lesion of unknown etiology, commonly associated with inflammatory conditions, and the term of pannus is usually used. Less frequently, ROP formation can develop with other noninflammatory entities, with atlantoaxial instability as most accepted pathophysiological mechanism for posttraumatic or degenerative ROP. As it can clinically and radiologically mimic a malignant tumor, it is paramount for the radiologist to know this entity. Magnetic resonance imaging is the modality of choice to reveal the possible severe complication of ROP in the form of a compressive myelopathy of the upper cervical cord. The purpose of the surgical treatment is the regression or complete disappearance of ROP, with posterior decompression by laminectomy and posterior C1-C2 or occipitocervical fixation. We present the case of an elderly patient with retroodontoid soft tissue mass secondary to a chronic atlantoaxial instability on os odontoideum, an extremely rare cause of ROP. The patient developed a posttraumatic cervical myelopathy related to the decompensation of this C1-C2 instability responsible for the formation of a compressive ROP. We will overview the retroodontoid pseudotumor and its differential diagnosis.

ABCs of the degenerative spine

Degenerative changes in the spine have high medical and socioeconomic significance. Imaging of the degenerative spine is a frequent challenge in radiology. The pathogenesis of this degenerative process represents a biomechanically related continuum of alterations, which can be identified with different imaging modalities. The aim of this article is to review radiological findings involving the intervertebral discs, end plates, bone marrow changes, facet joints and the spinal canal in relation to the pathogenesis of degenerative changes in the spine. Findings are described in association with the clinical symptoms they may cause, with a brief review of the possible treatment options. The article provides an illustrated review on the topic for radiology residents.

TEACHING POINTS

• The adjacent vertebrae, intervertebral disc, ligaments and facet joints constitute a spinal unit. • Degenerative change is a response to insults, such as mechanical or metabolic injury. • Spine degeneration is a biomechanically related continuum of alterations evolving over time.