Hydroxyapatite crystal deposition disease around the hip: a rare cause of piriformis syndrome and ischiofemoral impingement.

Hydroxyapatite crystal deposition disease (HADD) around the hip is typically described involving the gluteal tendons. However, HADD can occur in any location and result in varied clinical presentations. Even with small deposits, symptoms can be significant and imaging findings may appear aggressive, mimicking infection and malignancy particularly when in an atypical location. We illustrate cases of both common and rare locations of HADD around the hip, in particular presenting as greater trochanteric pain syndrome, piriformis syndrome and ischiofemoral impingement. The latter two manifestations have not been previously described in the literature. Low signal deposits were identified on MRI at the greater trochanter (gluteus medius tendon), proximal piriformis (adjacent to the sciatic nerve), and quadratus femoris (in the ischiofemoral space), respectively. Associated inflammatory changes with tendinopathy, bursitis and oedema were also demonstrated. The patient with piriformis syndrome underwent steroid injections and shockwave therapy with significant symptom improvement. HADD should be within the differential diagnosis for hip pain and nerve compression syndromes. Knowledge of tendon anatomy and correlation with radiographs or CT, even after MRI, is crucial in recognising unusual manifestations and preventing unnecessary investigation. Therefore, we review the spectrum of imaging features of HADD, as well as the current evidence on its management, to confidently diagnose this condition.

Subtalar joint middle facet agenesis: a case report and literature review.

Articular facet morphology plays a fundamental role in subtalar joint biomechanics and stability, and likely influences the development of hindfoot osteoarthritis. While multiple anatomical studies have shown wide variation in articular facet configuration, the clinico-radiological findings are rarely presented. We illustrate a case of bilateral subtalar joint middle facet agenesis in a 45-year-old woman, which was missed despite several presentations. We demonstrate the imaging findings to enable clinicians to distinguish this from the more common middle facet coalition. We summarise the developmental anatomy and discuss the potential implications on biomechanical function. Recognition of middle facet agenesis within the complex subtalar joint is important to prevent misdiagnosis and unnecessary surgery.

Comparison of MRI and CT in the Evaluation of Unilateral Maxillary Sinus Opacification.

OBJECTIVES: To evaluate the diagnostic performance of MRI compared with CT in differentiating neoplastic from infectious/inflammatory causes of complete unilateral maxillary sinus opacification (UMSO). Although MRI is increasingly used, no studies validate its utility compared to CT or nasal endoscopy in this context. METHODS: A retrospective analysis of 49 patients presenting with complete UMSO to a tertiary referral centre was performed, investigated with both CT and MRI. Two head and neck radiologists independently reviewed each imaging modality and recorded both a final diagnosis and Likert-scale diagnostic certainty score. A consensus radiological diagnosis was determined, stratified into potentially neoplastic or infectious/inflammatory aetiology, and compared with nasal endoscopy and final diagnosis. Diagnostic performance and interoperator agreement for predicting neoplasia were calculated. RESULTS: Both CT and MRI demonstrated high sensitivity and negative predictive value for neoplasm, although MRI was more specific (79%; 95% CI: 60-92%) than CT (14%; 95% CI: 4-32%), with a higher positive predictive value. MRI was more accurate (88%; 95% CI: 75-95%) than CT (49%; 95% CI: 34-64%) in diagnosing neoplasia. MRI had significantly higher diagnostic certainty Likert scores than CT (p < 0.0001 for both observers). Interobserver agreement was fair for CT (kappa coefficient = 0.327) and excellent for MRI (kappa coefficient = 0.918). CONCLUSIONS: MRI is more specific than CT in characterising UMSO, with greater diagnostic certainty and reproducibility. The additive diagnostic value of MRI complements CT, potentially reducing diagnostic delays in some cases and the need for diagnostic endoscopic sinus surgery in others. We recommend MRI incorporation into the diagnostic pathway for patients with UMSO.

Internal jugular vein aneurysm in an adult: diagnosis on non-invasive imaging.

We report the case of a 48-year-old man with a right fusiform internal jugular venous aneurysm, presenting as a unilateral painless neck swelling on coughing or laughing. This is a rare condition, more commonly seen in the paediatric population and can be diagnosed using non-invasive modalities such as Doppler ultrasound and contrast-enhanced CT. This anomaly is frequently misdiagnosed or overlooked, and our case highlights the importance of considering venous aneurysm as a differential to prevent invasive imaging and inappropriate management.