Postoperative ultrasonography of the musculoskeletal system

Ultrasonography of the postoperative musculoskeletal system plays an important role in the Epub ahead of print accurate diagnosis of abnormal lesions in the bone and soft tissues. Ultrasonography is a fast and reliable method with no harmful irradiation for the evaluation of postoperative musculoskeletal complications. In particular, it is not affected by the excessive metal artifacts that appear on computed tomography or magnetic resonance imaging. Another benefit of ultrasonography is its capability to dynamically assess the pathologic movement in joints, muscles, or tendons. This article discusses the frequent applications of musculoskeletal ultrasonography in various postoperative situations including those involving the soft tissues around the metal hardware, arthroplasty, postoperative tendons, recurrent soft tissue tumors, bone unions, and amputation surgery.

Ultrasonography of soft tissue "oops lesions"

In this article, I would like to define "oops lesions" as soft tissue mass-like lesions that involve surprise or embarrassment for radiologists following the final diagnosis. Examples of "oops lesions" include malignant tumors that appear benign, malignancy-mimicking benign tumors, incorrect identification of epidermal inclusion cysts, and soft tissue pseudotumors. Ultrasonography (US) findings are very helpful in the diagnosis of soft tissue tumors; however, the diagnosis of soft tissue tumors on the basis of US findings alone has some limitations. Therefore, clinical findings, laboratory data, findings from additional imaging modalities, and demographic data of patients should be considered together with US findings.

Periosteal Osteosarcoma Arising from the Rib and Scapula: Imaging Features in Two Cases

Periosteal osteosarcoma is an extremely rare chondroblastic osteosarcoma in the flat bone. There were authors reporting of two cases of periosteal osteosarcoma in the highly unusual sites. One of them arose from the rib, in a 17-year-old male, which appeared as a hypodense juxtacortical mass with periosteal reaction on CT. The other one arose from the scapula, in a 17-year-old female, which showed the intermediate signal intensity (SI) on T1-weighted image (WI), heterogeneous high SI on T2WI, and rim-enhancement on contrast-enhanced T1WI with cortical destruction on MRI.

Soft Tissue Masses Showing Low Signal Intensity on T2-weighted Images: Correlation with Pathologic Findings

OBJECTIVE: The aims of this article are to differentiate soft tissue masses showing low signal intensity on T2-weighted images (T2WIs) according to the histopathologic findings. CONCLUSION: To know relatively small numbered soft tissue masses with low signal intensities on T2WIs adding characteristic location, morphology, signal intensities on other sequences might be helpful for differential diagnosis of mostly nonspecific soft tissue tumors on MRI.

The Usefulness of Ultrasonography in Painful Hip

The causes of hip pain are variable, and, due to its size and deep position, complete physical examination is often difficult. In the past, ultrasonography (US) for the hip was mainly performed in order to rule out developmental hip dysplasia in infants or for evaluation of joint effusion. Now, however, US of the hip has been widely accepted as a useful modality in patients with hip pain and is commonly used in both adults and children. Joint effusion, bursitis, tendinosis or tendon tear, and acetabular labral tear can be main targets. Dynamic study for snapping hip is another unique advantage of US. In addition, US is very useful for guided procedures - aspiration, biopsy, or injection. In this review, the authors will discuss US findings of these common lesions with a brief review of anatomy.

Ultrasonographic Diagnosis of the Knee

Knee ultrasonography is a feasible and useful diagnostic method not only for the evaluation of periarticular soft tissues but also for intra-articular lesions and for the diagnosis of tumorous disease. Joint effusion, synovial thickening, intra-articular loose bodies, bursal and/or other fluid collection, ganglionic cysts, ligament and tendon injuries, tendinosis, osteomyelitis, and symptoms related to metallic hardware can be diagnosed using ultrasonography.

Synovial Lesions with Low Signal Intensities on T2-Weighted MR Image

Pigmented villonodular synovitis, synovial chondromatosis, long-standing rheumatoid arthritis, hemophilic arthropathy, chronic tophaceous gout, amyloid arthropathy, tuberculous arthritis, and hemangioma are the synovial diseases showing low signal intensity on T2-weighted image. Synovial deposition of hemosiderin, urate, and amyloid and fibrosis or caseous necrosis of hypertrophied synovium are known as the pathologic causes of T2 signal intensity. Because of the low incidence of the synovial lesions showing T2 low signal intensity, recognition of these diseases would be helpful for the exact diagnosis.

Synovial Lesions with Low Signal Intensities on T2-Weighted MR Image

Pigmented villonodular synovitis, synovial chondromatosis, long-standing rheumatoid arthritis, hemophilic arthropathy, chronic tophaceous gout, amyloid arthropathy, tuberculous arthritis, and hemangioma are the synovial diseases showing low signal intensity on T2-weighted image. Synovial deposition of hemosiderin, urate, and amyloid and fibrosis or caseous necrosis of hypertrophied synovium are known as the pathologic causes of T2 signal intensity. Because of the low incidence of the synovial lesions showing T2 low signal intensity, recognition of these diseases would be helpful for the exact diagnosis.

Ultrasound Diagnosis of Either an Occult or Missed Fracture of an Extremity in Pediatric-Aged Children

OBJECTIVE: To report and assess the usefulness of ultrasound (US) findings for occult fractures of growing bones. MATERIALS AND METHODS: For six years, US scans were performed in children younger than 15 years who were referred with trauma-related local pain and swelling of the extremities. As a routine US examination, the soft tissue, bones, and adjacent joints were examined in the area of discomfort, in addition to the asymptomatic contralateral extremity for comparison. Twenty-five occult fractures in 25 children (age range, five months-15 years; average age, 7.7 years) were confirmed by initial and follow-up radiograms, additional imaging studies, and clinical observation longer than three weeks. RESULTS: The most common site of occult fractures was the elbow (n = 9, 36%), followed by the knee (n = 7, 28%), ischium (n = 4, 16%), distal fibula (n = 3, 12%), proximal femur (n = 1, 4%), and humeral shaft (n = 1, 4%). On the retrograde review of the routine radiographs, 13 out of the 25 cases showed no bone abnormalities except for various soft tissue swelling. For the US findings, cortical discontinuity (direct sign of a fracture) was clearly visualized in 23 cases (92%) and was questionable in two (8%). As auxiliary US findings (indirect signs of a fracture), step-off deformities, tiny avulsed bone fragments, double-line appearance of cortical margins, and diffuse irregularity of the bone surfaces were identified. CONCLUSION: Performing US for soft tissue and bone surfaces with pain and swelling, with or without trauma history in the extremities, is important for diagnosing occult or missed fractures of immature bones in pediatric-aged children.

Fine Needle Aspiration Cytology of Alveolar Soft Part Sarcoma: A Case Report / 대한세포병리학회지

Alveolar soft part sarcoma (ASPS) is a rare soft tissue sarcoma, which occurs predominantly in adolescents and young adults. The cytological characteristics of this condition have been described only rarely in the literature. Here, we report a case of alveolar soft part sarcoma. A 28-year-old man presented with a mass in his right buttock, which had persisted for three years. The mass was subjected to a fine needle aspiration cytology (FNAC). The smears were cellular. The observed tumor cells were round or polygonal, and exhibited vesicular nuclei with prominent nucleoli and finely granular cytoplasm. Naked nuclei were frequently detected. Tumor cells were arranged singularly, but occasionally in a pseudoalveolar pattern.

Sonographic Findings of Calcific Tendinitis around the Hip

PURPOSE: To evaluate the sonographic findings of calcific tendinitis around the hip. MATERIALS and METHODS: Ten patients (7 women and 3 men; mean age, 42 years; age range, 34-52 years) with a diagnosis of calcific tendinitis around the hip were evaluated. All the patients underwent radiography and sonography (color Doppler sonography in 6 patients). The sonographic findings were analyzed to determine the level of tendon thickening compared with the contralateral side as well as the shape and posterior acoustic shadowing of the calcification, and vascularity on color Doppler sonography. RESULTS: In all cases, sonography showed a thickening of the tendon compared with the contralateral normal tendon as well as hyperechoic calcific shadows within the thickened tendon. Intratendinous calcifications were mainly observed as a homogeneous ovoid hyperechoic shadow with or without acoustic shadowing. Color Doppler sonography showed increased vascularity within or around the thickened tendon in four of the six patients. CONCLUSION: Sonography is effective in detecting a thickening of the tendon as well as intratendinous calcification, and can be used to diagnose calcific tendinitis around the hip.

Synovial Sarcoma with Massive Myxoid Feature: A Case Report

Focal myxoid change in synovial sarcoma is not uncommon, although the presence of predominantly myxoid stroma is very rare. Recognition of synovial sarcomas with massive myxoid feature is important because these can easily be mistaken for other myxoid soft tissue neoplasms. We report a case of a synovial sarcoma with massive myxoid feature in the left thigh of a 54-year-old woman. Wide excision of an 8.5*7.0*5.0 cm, well-circumscribed and lobulated tumor was performed. The cut surface was gray, soft, and myxoid. Histological examination showed proliferation of spindle cells in the predominantly myxoid stroma. There were small areas with features more typical of synovial sarcoma, including uniform, spindled cells with fascicular growth patterns, collagenous stroma, mast cell infiltration, and hemangiopericytoma-like vascular patterns. Immunohistochemical examination showed focal positivity of the tumor cells for epithelial membrane antigen (EMA). Tumor cells were all negative for cytokeratin (AE1/AE3), cytokeratin 7, S-100 protein, smooth muscle actin, and desmin. Ultrastructurally, tumor cells showed desmosomes and microvilli. Our case underscores that, in order to make a correct diagnosis, immunohistochemical and ultrastructural examination is essential.

Metastatic Bone Tumors with Sunburst Periosteal Reaction

PURPOSE: The purpose of this study was to describe the clinical and imaging features of metastatic bone tumors with sunburst periosteal reaction and to define the characteristic findings which would be helpful for differentiating metastatic bone tumors from primary malignant bone tumors. MATERIALS AND METHODS: The authors retrospectively reviewed the cases of nine patients with pathologically confirmed metastatic bone tumors with sunburst periosteal reaction, for which imaging studies (plain radiographs [n=9], radioisotope [RI] scans [n=4], magnetic resonance [MR] images [n=6], and computed tomographic [CT] scans [n=4]) were performed. The imaging studies of each lesion were analyzed by two musculoskeletal radiologists focusing on the metastatic site, patterns of bone response, signal intensity characteristics and pattern of contrast enhancement on MR. The clinical records of the patients were reviewed with regard to the age and sex of the subjects, the clinical presentation, and the origin of the primary tumors. RESULTS: The cases consisted of six men and three women, whose mean age was 62 years (age range, 50-88 years). The primary tumors were adenocarcinoma of the stomach [n=4], adenocarcinoma of the lung [n=2], adenocarcinoma of the prostate [n=1], hepatocellular carcinoma of the liver [n=1], and adenocarcinoma of unknown origin [n=1]. The sites of metastatic involvement exhibiting sunburst periosteal reaction were the scapula [n=2], proximal humerus [n=2], rib [n=1], iliac bone [n=1], tibia [n=1], spine [n=1], and proximal phalanx [n=1]. In all patients, the imaging findings showed osteolytic [n=3] or osteoblastic [n=6] lesions with sunburst periosteal reaction. In six cases, the lesions were iso-intense on the T1-weighted images and heterogeneously hyperintense on the T2-weighted images. The gadolinium-enhanced T1-weighted images showed a nearly homogenous enhancement of the lesions without any central necrotic portion. CONCLUSION: Although metastatic bone tumor exhibiting sunburst periosteal reaction is rare, it should be included along with primary malignant bone tumors in the differential diagnosis of bone lesions with sunburst periosteal reaction, especially in older patients with or without a known primary malignancy.

Ewing's Sarcoma of the Calcaneus: A Case Report / 영남의대학술지

Ewing's sarcoma is rarely found occurs in the bones of the hands and feet. We report a case of Ewing's sarcoma of the left calcaneus in a 15-year-old girl who complained of left heel pain and swelling. An open biopsy was performed and histological examination showed the proliferation of uniform small round cells. Immunohistochemical staining for CD99 showed diffuse strong positivity in the cytoplasmic membrane of the tumor cells. After preoperative chemotherapy, a below knee amputation was performed.

Non-Infectious Ischiogluteal Bursitis: MRI Findings

OBJECTIVE: We wished to report on the MRI findings of non-infectious ischiogluteal bursitis. MATER AND METHODS: The MRI findings of 17 confirmed cases of non-infectious ischiogluteal bursitis were analyzed: four out of the 17 cases were confirmed with surgery, and the remaining 13 cases were confirmed with MRI plus the clinical data. RESULTS: The enlarged bursae were located deep to the gluteus muscles and postero-inferior to the ischial tuberosity. The superior ends of the bursal sacs abutted to the infero-medial aspect of the ischial tuberosity. The signal intensity within the enlarged bursa on T1-weighted image (WI) was hypo-intense in three cases (3/17, 17.6%), iso-intense in 10 cases (10/17, 58.9%), and hyper-intense in four cases (4/17, 23.5%) in comparison to that of surrounding muscles. The bursal sac appeared homogeneous in 13 patients (13/17, 76.5%) and heterogeneous in the remaining four patients (4/17, 23.5%) on T1-WI. On T2-WI, the bursa was hyper-intense in all cases (17/17, 100%) ; it was heterogeneous in 10 cases and homogeneous in seven cases. The heterogeneity was variable depending on the degree of the blood-fluid levels and the septae within the bursae. With contrast enhancement, the inner wall of the bursae was smooth (5/17 cases), and irregular (12/17 cases) because of the synovial proliferation and septation. CONCLUSION: Ischiogluteal bursitis can be diagnosed with MRI by its characteristic location and cystic appearance.

Calcifying Aponeurotic Fibroma: A Case Report / 영남의대학술지

Calcifying aponeurotic fibroma is a rare benign soft tissue tumor that usually involves distal extremities in children and adolescents, especially the hands and feet. We report a case of calcifying aponeurotic fibroma arising in a 14-year-old boy who complained of right thumb mass. Surgical excision was performed. The resected specimen showed a 2.0x1.5 cm grayish white, fibrotic tissue. Histologic examination showed proliferation of fibroblastic cells with infiltrative growth pattern. Foci of calcification and chondroid differentiation were present.

Calcifying Aponeurotic Fibroma: A Case Report / 영남의대학술지

Calcifying aponeurotic fibroma is a rare benign soft tissue tumor that usually involves distal extremities in children and adolescents, especially the hands and feet. We report a case of calcifying aponeurotic fibroma arising in a 14-year-old boy who complained of right thumb mass. Surgical excision was performed. The resected specimen showed a 2.0x1.5 cm grayish white, fibrotic tissue. Histologic examination showed proliferation of fibroblastic cells with infiltrative growth pattern. Foci of calcification and chondroid differentiation were present.

Transarticular Invasion of the Sacroiliac Joints by Malignant Pelvic Bone Tumors

PURPOSE: To describe modes of transarticular invasion, with reference to the size and location of a tumor, the anatomic characteristics of invaded cartilage, and the existence of ankylosis in SI joint. MATERIALS AND METHODS: Eleven histologically confirmed malignant pelvic bone tumors involving transarticular invasion of sacroiliac joints, were retrospectively analysed. Transarticular invasion of a joint was defined as involvement of its opposing bones. The anatomic site and size of the tumors were analysed, and invaded sacroiliac joint was divided into upper, middle and lower parts on the basis of the anatomic characteristics of the intervening cartilage: synovial hyaline or fibrous ligamentous. The existence of ankylosis was determined, and transarticular invasion directly across a joint was classified as direct invasion. Extension of tumors around a joint from its periphery to the opposing bone were considered as indirect invasion. RESULTS: All tumors were located near the sacroiliac joint, eight at the ilium and three at the sacrum. Six invasions were indirect and five were direct. Average tumor area was larger in indirect cases than in direct: 191.8 cm2 vs. 69.6 cm2. In all indirect invasions, a huge soft tissue mass abutted onto the peripheral portion of the sacroiliac joint. In five of six cases of indirect transarticular invasion, the upper part of the joint posteriorly located fibrous ligamentous cartilage. In the other, the lower part was invaded, and this involved a detour around the joint space, avoiding the invasion of intervening cartilage. Ankylosis occurred in one of the indirect cases. Among the five cases of direct invasion, there was invasion of the posteriorly located ligamentous fibrous cartilage in three without ankylosis. In the other two cases, involving ankylosis, the synovial hyaline cartilage was invaded directly at the lower part of the joint. CONCLUSION: Transarticular invasions of sacroiliac joint via fibrous cartilage are most common. Ankylosis of the sacroiliac joint facilitates hyaline cartilage invasion. We consider that in transarticular invasion of malignant pelvic bone tumors, indirect invasion is more common than direct.

Clinical Situations in which Musculoskeletal Ultrasound is Helpful / 영남의대학술지

Musculoskeletal ultrasound (MSUS) has newly evolved by the mechanical improvement of the machine over past several years, becoming a part of imaging techniques for the evaluation of variable diseases in the musculoskeletal system. MSUS has proven diagnostic superiority in pathologies including rotator cuff disease of the shoulder, lateral epicondylitis of the elbow, diseases of the peripheral nerve, detection of intra-articular loose bodies and soft tissue foreign bodies, and in evaluating small superficial soft tissue tumors such as ganglion, epidermoid cyst, and glomus tumor. Besides, MSUS is very useful for obtaining tissue or fluid via percutaneous fine needle aspiration and/or biopsy for the histopathologic diagnosis. Combining MSUS with MR would play a great role in the field of the diagnostic imaging of the musculoskeletal system. The MSUS examiner should have the knowledge of cross-sectional anatomy, and of the mechanical and physical properties of ultrasound in order to interpret the ultrasound findings accurately and properly, and to avoid diagnostic errors due to variable artifacts subsequently. The goal of this article is to introduce the capabilities of MSUS in certain kinds of clinical situation and to familiarize the reader with MSUS. For the purpose, author intends to describe this article according not to the disease-, or organ-based, but to the clinical problem-based format.

MR Findings of Tuberculous Arthritis: Significance of Tuberculoma

PURPOSE: To determine the magnetic resonance (MR) imaging findings of tuberculous arthritis, and the frequency-in such cases-with which tuberculoma occurs. MATERIALS AND METHODS: MR images of 26 patients (M:F, 14:12; mean age, 46.2 years) with pathologically proven tuberculous arthritis were retrospectively reviewed. The presence of joint effusion, subchondral erosion, synovial proliferation and soft tissue abscess, and whether the inner wall of this abscess was smooth, were assessed. In particular, we determined whether a nodular lesion which showed low SI on T1WI, central low SI with peripheral high SI on T2WI, and rim enhancement on contrast study, was a tuberculoma. RESULTS: The joints involved were those of the knee (n=7), hip (n=7), shoulder (n=4), sacroiliac region (n=3), elbow (n=3), and ankle (n=2). Joint effusion was noted in 15 cases (58%), and subchondral erosion in 24(92%). synovial proliferation was found in 23 cases (88%), and soft tissue abscess in 24 (92%). The inner wall of this abscess was irregular in 17 cases (71%). A tuberculoma was present in intra- or extra-articular soft tissue in 18 cases (69%). CONCLUSION: The MR findings of tuberculous arthritis were subchondral erosion, synovial proliferation, and soft tissue abscess. The presence of a tuberculoma in intra- or extra-articular soft tissue, a specific finding in tuberculous arthritis, was noted in 69% of our cases.