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Osteoblast Wnt/β‐catenin signaling conditions skeletal development and health. Bone formation is stimulated when on the osteoblast surface a Wnt binds to low‐density lipoprotein receptor‐related protein 5 (LRP5) or 6 (LRP6), in turn coupled to a frizzled receptor. Sclerostin and dickkopf1 inhibit osteogenesis if either links selectively to the first β‐propeller of LRP5 or LRP6, thereby disassociating these cognate co‐receptors from the frizzled receptor. Sixteen heterozygous mutations identified since 2002 within LRP5 and three heterozygous mutations identified since 2019 within LRP6 prevent this binding of sclerostin or dickkopf1 and account for the exceptionally rare, but highly instructive, autosomal dominant disorders called LRP5 and LRP6 high bone mass (HBM). Herein, we characterize LRP6 HBM in the first large affected family. Their novel heterozygous LRP6 missense mutation (c.719C>T, p.Thr240Ile) was present in two middle‐aged sisters and three of their sons. They considered themselves healthy. Their broad jaw and torus palatinus developed during childhood and, contrary to the two previous reports of LRP6 HBM, the appearance of their adult dentition was unremarkable. Skeletal modeling, defined radiographically, supported classification as an endosteal hyperostosis. Areal bone mineral density (g/cm2) of the lumbar spine and total hip featured accelerated increases reaching Z‐scores of ~ +8 and +6, respectively, although biochemical markers of bone formation were normal. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Xanthogranulomatous epithelial tumor (XGET) and keratin-positive giant cell-rich soft tissue tumor with HMGA2-NCOR2 fusion (KPGCT) are two recently described neoplasms with both distinct and overlapping clinical and histopathologic features. We hypothesized that XGET and KPGCT may be related and represent a histologic spectrum of a single entity. To test this, we sought to characterize the clinical, radiographic, immunohistochemical, ultrastructural and molecular features of additional tumors with features of XGET and/or KPGCT, which we refer to descriptively as keratin-positive xanthogranulomatous/giant cell-rich tumors (KPXG/GCT). The archives were searched for potential cases of KPXG/GCT. Clinical and imaging features were noted. Slides were assessed for histologic and immunohistochemical findings. Ultrastructural and next generation RNA sequencing-based analysis were also performed. Nine cases were identified arising in seven women and two men [median age of 33 years (range: 12–87)]. Median tumor size was 4 cm (range: 2.4–14.0 cm) and tumors presented in the thigh (2), buttock (1), forearm (2), groin (1), cranial fossa (1), ilium (1), and tibia (1). Morphologically, tumors were most frequently characterized by a fibrous capsule, with associated lymphoid reaction, enclosing a polymorphous proliferation of histiocytes, giant cells (Touton and osteoclast-types), mixed inflammatory infiltrate, hemorrhage and hemosiderin deposition, which imparted a variably xanthogranulomatous to giant cell tumor-like appearance. One case clearly showed mononuclear cells with eosinophilic cytoplasm characteristic of XGET. All cases expressed keratin and 7 of 9 were found to harbor HMGA2-NCOR2 fusions including cases with xanthogranulomatous appearance. One patient developed local recurrence and multifocal pulmonary lesions, which were radiographically suspicious for metastases. Shared clinical, histologic and immunohistochemical features, and the shared presence of HMGA2-NCOR2 fusions supports interpretation of KPXG/GCT as a single entity which includes XGET and KPGCT. Given limited clinical follow-up to date and rare cases with apparently aggressive findings, we provisionally regard these tumors as having uncertain biologic potential.

Tibial plateau fractures are common fractures which are often associated with concurrent soft tissue injury and for which accurate preoperative diagnosis is important for development of an appropriate treatment plan and outcome prediction. Here, we present an extreme manifestation of the pivot shift phenomenon with an unusual tibial plateau fracture with flipped component not described by any existing tibial plateau fracture classification system and never reported previously in conjunction with an anterior cruciate ligament injury. We describe the utilization of advanced imaging not typically utilized in the management of tibial plateau fractures in combination with clinical suspicion to diagnose the associated soft tissue injuries and develop an appropriate management plan.

The impact of stroke on the lives of individuals and the health-care system is considerable. Damage from stroke can be limited if the treatment is administered at the appropriate time, so early recognition is essential. Some common interventions (e.g., FAST) designed to help potential stroke victims discriminate stroke symptoms often result in false negatives. Strokes can present with a wide variety of symptoms, making it difficult to discriminate stroke symptoms from non-stroke symptoms. Because the probability that a given set of symptoms are stroke symptoms is typically unknown to the victim, the problem is a decision under conditions of uncertainty. Signal detection methodology allows us to consider the ability of an individual or group to discriminate between stroke symptoms and non-stroke symptoms, as well as measure the motivation or bias toward a particular decision. We examined the effects of levels of feedback on performance of a random sample of participants from Amazon Mechanical Turk. We found that feedback designed to generate liberal bias toward stroke detection yielded fewer misses than FAST while maintaining a false alarm rate below 50%. Given that strokes are difficult to discriminate, this suggests that interventions should be focused on incentivizing help-seeking behaviors in conditions of uncertainty for those most at risk.

Objectives To evaluate diagnostic yield and accuracy of image-guided core needle biopsy (ICNB) of suspected malignant osseous lesions in a large cohort of adults, evaluate what factors influence these measures, and offer technical recommendations to optimize yield. Methods A retrospective analysis of 2321 ICNBs performed from 2010 to 2021 was completed. The diagnostic yield and accuracy of the biopsies as well as a series of patient, lesion-related, and technical factors were retrospectively analyzed. Multivariate statistical analysis was performed to evaluate what factors were associated with yield and accuracy. Different cutoff values of total core length and core number were then tested to determine threshold values in relation to increased diagnostic yield. Results Diagnostic yield was 98.2% (2279/2321) and accuracy was 97.6% (120/123). Increased total core length (odds ratio [OR] = 2.34, 95% confidence interval [CI] (1.41–3.90), p  = 0.001), core number (OR = 1.51, 95% CI (1.06–2.16), p  = 0.02) and presence of primary malignancy (OR = 2.81, 95% CI (1.40–5.62), p  = 0.004) were associated with improved yield. Lesion location in an extremity (OR = 0.27, 95% CI (0.11–0.68), p  = 0.006) and using fluoroscopic imaging guidance (OR = 0.33, 95% CI (0.12–0.90), p  = 0.03) were associated with lower yield. Cutoff thresholds in relation to increased diagnostic yield were found to be 20 mm total core length (marginal OR = 4.16, 95% CI = (2.09–9.03), p < 0.001), and three total cores obtained (marginal OR = 2.78, 95% CI (1.34–6.54), p  = 0.005). None of the analyzed factors influenced diagnostic accuracy. Conclusions ICNB has a high rate of diagnostic yield and accuracy. Several factors influence diagnostic yield; 20 mm core length and three total cores optimize yield. Clinical relevance statement Image-guided core needle biopsy of suspected malignant osseous lesions is a safe procedure with a very high rate of diagnostic yield and accuracy. Obtaining 20 mm total core length and three total cores optimizes diagnostic yield. Key Points • In a retrospective cohort study, image-guided core needle biopsy of suspected osseous malignant lesions in adults was found to have very high rates of diagnostic yield and accuracy. • Increased total core length and core number of biopsies were each associated with increased diagnostic yield, and these relationships reached thresholds at 20 mm total core length and three total cores obtained. • The presence of a known primary malignancy was also associated with increased yield while using fluoroscopic imaging guidance and lesion location in an extremity were associated with decreased yield.

BackgroundStress fractures of the upper extremities in athletes are important injuries for radiologists to appreciate despite being far less common than stress fractures of the lower extremities. Among upper extremity stress fractures, those involving the olecranon have been well described in overhead pitching athletes. Isolated stress fractures of the ulnar shaft however are less commonly reported in the literature and considered to be rare. We have observed a correlation between young patients with ulnar shaft stress fractures and the activity of fast-pitch softball pitching.Case ReportsIn this series, we present the imaging findings in four cases of ulnar shaft stress fractures in softball pitchers who presented with insidious onset forearm pain. Furthermore, a review of the literature focusing on softball pitching mechanics is provided to offer a potential underlying mechanism for the occurrence and location of these injuries.ConclusionAn awareness of the imaging appearance of ulnar shaft stress fractures along with an understanding of its proposed mechanism will facilitate accurate and timely imaging diagnosis of this injury by the radiologist.

Neoplasms of the sacrum are rare. Given the non-specific imaging findings in sacral lesions, the imaging-based differential diagnosis is always difficult. This case is about an adult with primary sacral neuroblastoma and we have discussed imaging and histopathological findings of this rare tumor.

BackgroundManagement of pectoralis major (PM) injuries is largely determined by the anatomic location of the injury, with tendon avulsions from the humerus requiring surgery while myotendinous (MT) injuries are typically managed non-operatively. Because physical examination cannot reliably make this distinction, MRI is often used for staging. However, correct classification can also be difficult with MRI where there is extensive soft tissue edema and distorted anatomy.ObjectiveTo determine the diagnostic performance of primary and secondary MRI signs of PM injury for distinguishing tendon avulsions from MT injuries in a selected sample of patients that underwent surgical repair using a practical interpretation algorithm.MethodsIn this retrospective study, 3 blinded observers independently assessed the MRI findings of 17 patients with PM injury (including 12 acute injuries, 4 chronic, and 1 of uncertain age) where subsequent surgery documented tendon avulsion (11) and MT injuries (6) by applying the primary MRI criteria of absent tendon at the humerus, retracted tendon stump, epicenter of edema, and the secondary finding of soft tissue edema contacting the anterior humeral cortex. Operative findings were used as the reference standard. Sensitivity, specificity, and positive and negative predictive value were recorded for each finding.ResultsThe primary MRI finding of lack of a visible tendon at the insertion (sensitivity 82–100%, specificity 100%) and the secondary finding of edema contacting the anterior humeral cortex (sensitivity 64–91%, specificity 67–100%) were both useful for the distinction of tendon avulsion from MT injury, particularly in acute injuries. The presence of a retracted tendon stump and the epicenter of edema were not reliable findings. The use of a decision tree including the secondary finding of humeral edema increased the sensitivity and specificity for 2 of the 3 observers.ConclusionMRI assessment of PM injury focused on the humeral insertion of the PM tendon allows accurate distinction of tendon avulsion from MT injury.Clinical impactThis study describes a practical approach to classifying PM injuries with MRI to distinguish injuries that require surgery from those that can potentially be managed conservatively.

We report a 19-year-old man with the rare occurrence of primary osseous Rosai–Dorfman disease (RDD). The patient presented with a painful, solitary, bone marrow-replacing lesion in the distal femur. A diagnosis of chronic osteomyelitis was initially made on tissue from a CT-guided needle biopsy of the lesion; however, the diagnosis of RDD was eventually made after histological and immunohistochemical analysis of material from a subsequent curettage. No lymphadenopathy or other sites of involvement were found on clinical evaluation and PET-CT. To our knowledge, this is the first report of solitary osseous RDD based on systemic staging with PET-CT. We review the clinical, imaging, and histological features of primary osseous RDD, including pitfalls in diagnosis.

Background: Renewed interest in anterior cruciate ligament (ACL) preservation has led to increased focus on tear location within the knee joint in treatment decisions, with primary ACL repair reserved for proximal tears. Retrospective studies have reported varying tear locations in adults when assessed on magnetic resonance imaging (MRI), with few studies comparing tear location on MRI versus intraoperative findings. Purpose: To prospectively determine the distribution of ACL tear location assessed on MRI versus intraoperative evaluation to test the hypothesis that <15% of ACL tears are proximal type avulsions. Study Design: Cohort study (Diagnosis); Level of evidence, 2. Methods: A total of 174 patients with clinically confirmed full-thickness ACL tears between August 2022 and March 2024 were identified and enrolled. Patients with partial tears, chronic injuries, recurrent ACL tears, or multiligamentous injuries were excluded. ACL tear locations were classified on preoperative MRI and intraoperatively using the modified Sherman classification. Patient demographic characteristics, injury mechanism, and surgical details were recorded. Analysis of variance and chi-square and Fisher exact tests were used for analysis, with significance set at P < .05. Results: ACL tear location based on MRI was as follows: 9.8% type I, 22.4% type II, 67.2% type III, and 0.60% type IV, with no type V tears. Arthroscopic tear location distribution was as follows: 26.4% type I (proximal avulsion), 44.8% type II (proximal), 25.8% type III (midsubstance), and 3.4% type IV (distal), with no type V tears. There was 43% agreement between arthroscopic and MRI evaluation overall, with 95.5% agreement when classifying type III tears. Type I tears were more common in older patients, whereas type III tears were more common in younger patients. No significant correlations were appreciated based on patient sex, body mass index, or injury mechanism. Conclusion: Poor agreement was found between imaging and arthroscopic assessment of ACL tear location, as MRI predicted intraoperative ACL tear location in less than half of cases. However, very good agreement was noted when classifying type III tears. Tear pattern was associated with patient age, with more type I tears in older patients and more type III tears in younger patients.