Primary lymphoma of bone of the little finger: a case report and review of the literature.

Primary lymphoma of bone (PLB) is a rare, malignant lymphoid proliferation within bone accounting for less than 3% of all malignant bone tumors. In this case report, a 61-year-old female with past medical history of gout presented with pain and swelling in her right little finger. Initial radiographs demonstrated periostitis and soft tissue swelling about the right little finger. She returned three months later with progressive pain. Subsequent MRI and repeat radiographs demonstrated near complete destruction of the right little finger middle phalanx and periostitis with marrow infiltration at the right long finger. Given the rapid progression of disease, the differential diagnosis consisted primarily of aggressive neoplastic processes. The little finger ray was amputated through the level of the metacarpophalangeal joint and histopathology demonstrated large neoplastic cells that stained positive with CD45, CD20, and PAX5, compatible with diffuse large B-cell lymphoma. A subsequent normal bone marrow aspiration and PET-CT demonstrated no additional sites of disease, thus excluding secondary lymphoma to bone. To the best of our knowledge, this is the first case report of polyostotic PLB involving the hand. PLB of the hands may be initially misdiagnosed due to its rarity and clinical presentation mimicking rheumatological disease. Clinical vigilance in concert with close imaging follow-up is required to make the diagnosis in a timely fashion. We also review the existing PLB hand literature which consists of five cases.

Fluoroscopic-guided procedures of the lower extremity.

This article reviews the literature and the authors' experiences regarding the performance of lower extremity fluoroscopically guided procedures from the hip to the toes. An overview of injections and aspirations, their indications, risks, and complications are provided, focusing on anesthetics, corticosteroids, and contrast agents. A variety of approaches to each joint and the associated pearls and pitfalls of each approach will be discussed.

Beyond schwannomas and neurofibromas: a radiological and histopathological review of lesser-known benign lesions that arise in association with peripheral nerves.

Peripheral nerve sheath tumors comprise a significant percentage of both benign and malignant soft tissue tumors. The vast majority of these lesions are schwannomas and neurofibromas, which most radiologists are familiar with including the well-described multimodality imaging features. However, numerous additional often under-recognized benign entities associated with nerves exist. These rarer entities are becoming increasingly encountered with the proliferation of cross-sectional imaging, particularly magnetic resonance imaging (MRI). It is important for the radiologist to have a basic understanding of these entities as many have near-pathognomonic MR imaging features as well as specific clinical presentations that when interpreted in concert, often allows for a limited differential or single best diagnosis. The ability to provide a prospective, pre-intervention diagnosis based solely on imaging and clinical presentation is crucial as several of these entities are "do not touch" lesions, for which even a biopsy may have deleterious consequences. To our knowledge, the majority of these benign entities associated with nerves have only been described in scattered case reports or small case series. Therefore, the aim of this article is to provide a radiopathologic comprehensive review of these benign entities that arise in association with nerves with a focus on characteristic MRI features, unique histopathologic findings, and entity specific clinical exam findings/presentation.

Tenosynovial giant cell tumor-diffuse type, treated with a novel colony-stimulating factor inhibitor, pexidartinib: initial experience with MRI findings in three patients.

Tenosynovial giant cell tumor-diffuse type (diffuse TSGCT) is a benign but locally aggressive proliferative disorder of the synovium. Treatment is usually surgical, although in cases of extensive disease complete synovectomy is not possible and local recurrence rates are high. Pexidartinib (trade name Turalio®), a colony-stimulating factor-1 (CSF-1) inhibitor, was shown in a recent phase III trial to effectively treat diffuse TSGCT and is FDA approved for the treatment of adult patients with symptomatic diffuse TSGCT associated with severe morbidity or functional limitations and not amenable to improvement with surgery. Pexidartinib is available only through a restricted program under a risk evaluation and mitigation strategy (REMS) because of the risk of hepatotoxicity. Magnetic resonance imaging (MRI) is the preferred imaging modality for the diagnosis and surveillance of TSGCT. Here we present three patients with diffuse TSGCT of the knee who underwent multiple MRIs over several years while on pexidartinib. We describe the disease burden and signal characteristics on MRI and correlate with the response reported in the patients' medical records. Given that the use of pexidartinib and other CSF inhibitors is likely to increase, musculoskeletal radiologists should be aware of this novel non-operative treatment and the MRI appearance of diffuse TSGCT during therapy.

Concepts in Musculoskeletal Bone and Soft Tissue Biopsy.

Imaging-guided needle biopsy of musculoskeletal lesions is a high-yield and low-risk procedure that can be used for definitive characterization of indeterminate bone and soft tissue lesions. Familiarity with the preprocedural, technical, and postprocedural steps is vital for the appropriate management of these cases. Biopsy request triage requires an awareness of definitively benign conditions and other tumor mimics. A complete clinical, laboratory, and imaging work-up is essential for procedural planning and determining pathologic concordance. Consultation with an orthopaedic oncologist is a requisite step to ensure maximizing biopsy yield and to avoid interference with any future limb-sparing surgical intervention. Knowledge of the equipment, pertinent medications, and appropriate biopsy technique can minimize the risk of periprocedural complications. Finally, the radiologist may be required to discuss the concordance of histopathology with preprocedure imaging, perform repeat image-guided biopsy, and carefully interpret sarcoma surveillance imaging examinations.

Percutaneous image-guided sternal biopsy: a cross-institutional retrospective review of diagnostic yield and safety in 50 cases.

OBJECTIVE: Image-guided sternal biopsy may be technically daunting given the immediately subjacent critical structures. There is a paucity of literature describing technique, safety, and efficacy. This study aims to quantify the diagnostic yield and safety of image-guided sternal biopsies. Secondary aims include (1) describing the preferred approach/technique and (2) identifying imaging features and disease entities associated with higher and lower diagnostic yields. MATERIALS AND METHODS: A retrospective review of 50 image-guided sternal biopsies performed at two quaternary care centers from 2000 to 2019 was performed. Recorded lesion-related variables included as follows: location, density, extraosseous extension, and size. Recorded variables from electronic medical records included as follows: patient demographics, histologic or microbiological diagnosis, and complications. Recorded technique-related variables included as follows: needle obliquity, type, and gauge; biopsy core number and length; and modality. RESULTS: Of the 50 biopsies, 88.0% resulted in a definitive histologic diagnosis. Six biopsies were non-diagnostic. The majority of biopsies were performed under computed tomography (88.0%), followed by ultrasound (12.0%). Tumor was the most common biopsy indication (90.0%), followed by infection (10.0%). Of the diagnostic biopsies indicated for tumor, 88.9% were malignant. Seventy-four percent of the lesions were predominantly lytic. Fifty percent of lesions had extraosseous extension. Lesion locations were as follows: manubrium (48.0%), sternal body (48.0%), and sternomanubrial joint (4.0%). No minor or major, acute, or delayed procedure-related complications were encountered. CONCLUSION: Image-guided sternal biopsy is an efficacious and safe method of obtaining a definitive histologic diagnosis regardless of lesion-specific features or location.

Radiographic Evidence of Soft-Tissue Gas 14 Days After Total Knee Arthroplasty Is Predictive of Early Prosthetic Joint Infection.

OBJECTIVE. The diagnosis of early prosthetic joint infection (PJI)-defined as within 6 weeks after a total knee arthroplasty (TKA)-can be difficult because of expected postsurgical changes and elevated inflammatory markers. The role of radiographic evaluation in this situation carries unclear clinical significance. This study had three primary aims: first, to determine when soft-tissue gas is no longer an expected postoperative radiographic finding; second, to determine whether soft-tissue gas is predictive of early PJI; and, third, to determine whether the presence of soft-tissue gas correlates with specific patient characteristics and microbiology culture results. MATERIALS AND METHODS. This retrospective study was of patients who underwent TKA from 2008 to 2018 with available imaging between 5 days and 6 weeks after TKA and no interval intervention before imaging. All confirmed early PJIs were included (n = 24 cases; 15 patients). For comparison, patients who underwent TKA but did not have a PJI (n = 180 cases; 150 patients) were selected randomly. Radiographs were reviewed by two readers. A two-tailed p < 0.05 was considered significant. RESULTS. Soft-tissue gas was identified on postoperative radiography of 13 of 24 (54.2%) cases (mean ± standard error of the mean [SEM], 28.3 ± 2.3 days after TKA) with early PJI and four of 180 (2.2%) cases (mean ± SEM, 15.3 ± 7.3 days after TKA) without PJI (p < 0.0001; odds ratio, 52.0 [95% CI, 14.7-156.9]). The presence of soft-tissue gas on radiography 14 days after TKA had a sensitivity of 0.54 (95% CI, 0.35-0.72) and specificity of 0.99 (95% CI, 0.97-1.00) for early PJI. Staphylococcus species were the dominant organisms; cases with soft-tissue gas showed a wider variety of microbiology species (p < 0.01). CONCLUSION. Postoperative soft-tissue gas present on radiography performed 14 days or more after TKA is predictive of early PJI and is associated with a wider spectrum of microorganisms.

Avulsion Injuries of the Hand and Wrist.

Injuries of the hand and wrist are frequently encountered in radiology. Avulsions of the hand and wrist are a heterogeneous group of injuries, but they often have a characteristic imaging appearance that relates to the intricate bone and soft-tissue anatomy and the mechanism of injury. The imaging appearance and this intricate form and function dictate treatment of hand and wrist avulsions. This article reviews frequently and infrequently encountered avulsion injuries and describes abnormalities that may mimic the imaging appearance of avulsions. Specifically discussed entities include the Bennett and reverse Bennett fracture, ulnar collateral ligament avulsion, radial and ulnar styloid process avulsion, triquetral avulsion, mallet and jersey finger, central slip avulsion, and acute and chronic volar plate avulsion injuries. Uncommon avulsion injuries are also described and include avulsions of the scapholunate ligament, extensor carpi radialis longus and brevis tendons, trapeziometacarpal ligament, radial collateral ligament, and flexor digitorum profundus tendon. Emphasis is placed on the relevant anatomy and typical imaging findings for each diagnosis, with pertinent clinical history, pathophysiologic evaluation, and treatment discussed briefly. Understanding the anatomy and expected imaging findings can aid the radiologist in recognizing and characterizing these injuries.©RSNA, 2020.

Pearls and Pitfalls for Soft-Tissue and Bone Biopsies: A Cross-Institutional Review.

Management of soft-tissue and bone neoplasms depends on a definitive histologic diagnosis. Percutaneous image-guided biopsy of bone and soft-tissue tumors is a cost-effective and accurate method to obtain a histopathologic diagnosis. Biopsy requests must be approached thoughtfully to avoid numerous potential pitfalls. Hasty biopsy planning places the patient at increased risk for misdiagnosis, delayed therapy, repeated invasive procedures, and substantial morbidity. Biopsy planning begins with a thorough review of the relevant clinical history and pertinent imaging. The biopsy route must be planned in concert with the referring orthopedic oncologist to preserve limb-sparing options. Carefully selecting the most appropriate imaging modality to guide the biopsy increases the chances of reaching a definitive diagnosis. It is also critical to identify and target with expertise the part of the lesion that is most likely to yield an accurate diagnosis. Percutaneous biopsy is a safe procedure, and familiarity with preprocedural laboratory testing parameters, anticoagulation guidelines, and commonly used sedation medications minimizes the risk of complications while ensuring patient comfort. Nondiagnostic biopsy results are not infrequent and may still have value in guiding patient treatment. Awareness of the imaging manifestations of tumor recurrence is also important. The aim of this article is to provide a comprehensive review of pertinent preprocedural, periprocedural, and postprocedural considerations for bone and soft-tissue musculoskeletal biopsies.The online slide presentation from the RSNA Annual Meeting is available for this article.©RSNA, 2020.

Low-grade Osteosarcomatous Dedifferentiation of an Atypical Lipomatous Tumor in a Pediatric Patient.

Atypical and malignant lipomatous tumors are infrequent in the pediatric population. Within this uncommon cohort, the morphologically and genetically related spectrum of atypical lipomatous tumor/well-differentiated liposarcoma/dedifferentiated liposarcoma (ALT/WDL/DDLS) is markedly rare. Their shared characteristic molecular aberration is a genomic amplicon of a region of chromosome 12q, including the oncogenes MDM2 and CDK4. We present an unusual case of a pediatric patient with an ALT, with recurrence after 2 years in the form of a bone-forming mass, radiologically and pathologically mimicking parosteal osteosarcoma, a tumor also molecularly characterized by amplification of MDM2 and CDK4. However, with ample histologic sampling, a single focus of lipogenic differentiation was identified, thus representing the first near complete low-grade osteosarcomatous dedififferentation reported within ALT/WDL/DDLS and the first ever in pediatric patient. The case serves a reminder of a diagnosis differential and pitfalls within MDM2-amplified tumors.

Naviculocuneiform and Second and Third Tarsometatarsal Articulations: Underappreciated Normal Anatomy and How It May Affect Fluoroscopy-Guided Injections.

OBJECTIVE: Because the second and third tarsometatarsal (TMT) and naviculocuneiform joints normally communicate, the least arthritic or technically most straightforward joint was injected when a fluoroscopically guided therapeutic injection was ordered for one or both joints. We hypothesized that pain relief would be equivalent regardless of the joint injected and would result in less radiation and a lower steroid dose compared with patients who had both articulations injected. MATERIALS AND METHODS: Seventy-eight patients were divided into four joint groups: naviculocuneiform requested and injected (n = 15), nonrequested naviculocuneiform or second and third TMT injected (n = 25), both injected (n = 23), and TMT requested and injected (n = 15). Variables recorded included patient age and sex, fluoroscopy time, steroid dose, pre- and postprocedural pain, osteoarthrosis (OA) grade, and confidence of intraarticular injection. Statistical analysis compared mean pain level change before and after injection, mean fluoroscopy time, and mean steroid dose between groups. The mean OA grade of the nonrequested joint was compared with that of the requested joint in patients whose injected and requested joints did not match (group 2). RESULTS: Pre- and postinjection pain reduction (p = 0.630) and postinjection pain (p = 0.935) were not significantly different. Mean steroid dose (p < 0.001) and fluoroscopy time (p = 0.0001) were significantly increased for the both joint injection group. Within the nonrequested naviculocuneiform or second and third TMT injection group, there was a significant difference in OA grade between injected (least arthritic) and requested joints (p = 0.001). CONCLUSION: When faced with challenging naviculocuneiform or second and third TMT joint injections, choosing the technically most straightforward joint may result in less radiation and steroid dose without compromising quality of care or pain reduction.

Nomenclature of Subchondral Nonneoplastic Bone Lesions.

OBJECTIVE. The purpose of this article is to summarize the nomenclature of nonneoplastic conditions affecting subchondral bone through a review of the medical literature and expert opinion of the Society of Skeletal Radiology Subchondral Bone Nomenclature Committee. CONCLUSION. This consensus statement summarizes current understanding of the pathophysiologic characteristics and imaging findings of subchondral nonneoplastic bone lesions and proposes nomenclature to improve effective communication across clinical specialties and help avoid diagnostic errors that could affect patient care.

Pearls and pitfalls of fluoroscopic-guided foot and ankle injections: what the radiologist needs to know.

OBJECTIVE: This article provides a comprehensive, joint-by-joint review of fluoroscopic-guided foot and ankle injections and emphasizes pre-procedural planning, relevant anatomy, appropriate technique, troubleshooting the difficult procedure, and the importance of communicating unexpected findings with the referring clinician. The interrogation of pain generators including variant ossicles, fractures, and post-surgical/traumatic findings is also described. CONCLUSIONS: Even the most challenging foot and ankle injections may be successfully completed with a solid anatomical understanding and thoughtful approach.

Multifocal metastatic chordoma to the soft tissues of the fingertips: a case report including sonographic features and a review of the literature.

Chordoma is a rare, locally aggressive tumor which commonly metastasizes, most often to the lung, liver, and spine. In this case report, a 59-year-old male with history of sacral chordoma and pulmonary metastases presented to the emergency department with swelling and discoloration of multiple left fingertips. The initial radiographs led to a presumptive diagnosis of gout, which did not respond to medical therapy. An ultrasound demonstrated multiple solid masses with vascular hyperechoic septations which were subsequently biopsied and proven to be metastatic chordoma. Metastatic disease to the hand is a well documented but rare manifestation of many malignancies. The clinical presentation and radiographic features of multifocal hand metastases may mimic entities such as systemic deposition and granulomatous diseases. To the best of our knowledge, this is the first case report of soft tissue chordoma metastases to the fingertips as well as the first reported sonographic description of chordoma metastases.

Multiligamentous Injury of the Knee: MRI Diagnosis and Injury Patterns.

Anterior cruciate and posterior cruciate injuries rarely occur in isolation and are often associated with injuries to the secondary or supporting structures that provide stability against rotational forces. These structures include the posterolateral and posteromedial corner ligaments and tendons, as well as the anterolateral ligament. If injuries to these secondary structures are not appreciated at the time of cruciate ligament reconstruction, an isolated cruciate ligament reconstruction may be predisposed to early failure. Thus it is crucial for radiologists interpreting knee magnetic resonance imaging to understand and report on injury to these ligaments and tendons at the time of initial injury to help the orthopaedic surgeon plan a comprehensive approach to ligament reconstruction. This strategy will ultimately result in improved patient outcomes.

Bilateral multifocal lower extremity localized soft tissue amyloidomas: case report with ultrasonographic characterization.

Amyloidosis may be acquired or hereditary and consists of multiple disease processes characterized by the abnormal deposition of extracellular fibrillary protein aggregates. The presentation of amyloidosis is varied, ranging from an isolated, focal deposition to systemic disease. While systemic involvement is common, a rare entity known as amyloidoma or tumor amyloidosis may also occur. The 75-year-old female in this case presented with slowly growing multifocal bilateral lower extremity masses and was ultimately diagnosed with localized amyloidomas in the absence of chronic illness or systemic disease. This case report includes a description of the sonographic features of localized extremity amyloidoma that, to the best of our knowledge, have not yet been described in the literature. Awareness of the sonographic features, and this unique presentation of multifocal soft tissue extremity amyloidomas will allow for this rare diagnosis to be included in a limited differential diagnosis.

Dynamic Contrast-enhanced MR Imaging Curve-type Analysis: Is It Helpful in the Differentiation of Prostate Cancer from Healthy Peripheral Zone?

PURPOSE: To evaluate the performance and interobserver agreement of qualitative dynamic contrast material enhanced magnetic resonance (MR) imaging curve analysis as described in the Prostate Imaging Reporting and Data System (PI-RADS) for the differentiation of prostate cancer (PCa) from healthy prostatic tissue in the peripheral zone (PZ). MATERIALS AND METHODS: This Health Insurance Portability and Accountability Act-compliant institutional review board-approved retrospective analysis included 120 consecutive pretreatment dynamic contrast-enhanced (DCE) MR imaging PCa examinations. Regions of interest (ROIs) were placed in 251 spots, including 95 (37.8%) in healthy PZ tissue and 156 (62.2%) in PCa, by using detailed histologic-multiparametric MR correlation review. Three radiologists reviewed the DCE time curves and assessed qualitative curve types as described in PI-RADS: type 1 (progressive), type 2 (plateau), or type 3 (washout). Receiver operating characteristic curve analysis was used to assess accuracy in differentiating PCa from healthy tissue on the basis of curve type, and κ was calculated to assess interobserver agreement. RESULTS: Receiver operating characteristic curves were similar for all observers, but mean areas under the receiver operating characteristic curve were poor (0.58 ± 0.04 [standard deviation] to 0.63 ± 0.04). No differences in accuracy were seen for varying DCE time resolution and imaging length. Observer agreement in assessment of type 3 versus types 1 or 2 curves was substantial (0.66 < κ < 0.79), better for PCa ROIs than for healthy-tissue ROIs. The agreement between type 1 and type 2 curves was moderate to substantial (0.49 < κ < 0.78). CONCLUSION: Qualitative DCE MR imaging time-curve-type analysis performs poorly for differentiation of PCa from healthy prostatic tissue. Interobserver agreement is excellent in assessment of type 3 curves but only moderate for type 1 and 2 curves.

From tumor to trauma: etiologically deconstructing a unique differential diagnosis of musculoskeletal entities with high signal intensity on T1-weighted MRI.

OBJECTIVE: This article reviews the neoplastic and nonneoplastic abnormalities of the musculoskeletal system that contain high signal intensity on T1-weighted MRI. The physical properties accounting for the increased signal intensity as well as the key clinical and imaging characteristics of each entity are discussed. CONCLUSION: Recognition of high signal intensity within musculoskeletal lesions on T1-weighted MRI can limit the differential diagnosis and can also have important clinical implications.

Osteoma of long bone: an expanding spectrum of imaging findings.

Osteoma of long bone is an extremely rare, benign bone-forming surface lesion with the largest published case series consisting of only 14 patients. The most important and often most difficult lesion to differentiate from osteoma of long bone radiographically is parosteal osteosarcoma, which is a rare, low-grade surface osteosarcoma with the potential for dedifferentiation. Reports of imaging studies of osteoma of long bone depict a well-defined ossified mass arising from the surface of the diaphysis or metadiaphysis of a long bone. A characteristic feature is the homogeneity of the mass, with uniform density near or equal to that of cortical bone from the base of the lesion to its periphery. The 45-year-old female in this case presented with left hip fullness and was subsequently found to have a proximal femoral osteoma, which was unique in that it contained large fatty marrow spaces that corresponded to bands of relatively low density on plain radiography and computed tomography, giving it a heterogeneous appearance atypical of osteoma of long bone. Furthermore, the osteoma reported here was associated with a small but separate nodular focus of ossification in the adjacent soft tissue. These findings led to a presumptive diagnosis of parosteal osteosarcoma with a local soft tissue metastasis or satellite nodule resulting in radical resection of the tumor. Definitive diagnosis of osteoma was made on histology of both the parent lesion and ossified nodule as no neoplastic spindle cell proliferation was present to establish a diagnosis of low-grade osteosarcoma. This represents, to the best of our knowledge, the first such presentation of osteoma of long bone.