Musculoskeletal sarcoidosis: spectrum of appearances at MR imaging

Rare and common manifestation of musculoskeletal and sinonasal sarcoidosis: A case report

Sarcoidosis is a systemic granulomatous disease that can affect multiple organ systems. Although many sarcoidosis patients are asymptomatic, the variable clinical progression of symptomatic patients and the nonspecific presentation make diagnosis difficult in certain cases. Musculoskeletal and sinonasal involvement of sarcoidosis are uncommon manifestations, and they are often only seen in patients with widespread disease. Diagnosis of osseous sarcoidosis, sarcoid arthropathy, and sarcoid rhinosinusitis are typically based on a combination of clinical history, radiological findings, and pathologic specimens. Although there are classic image findings, such as lacelike honeycomb appearance of small bones of the hands or hilar/mediastinal lymphadenopathy, sole reliance on image findings for the diagnosis of sarcoidosis is unreasonable as many findings are nonspecific. However, failure to include sarcoidosis in the differential diagnosis often leads to a delay in recognition of musculoskeletal or sinonasal involvement and results in ineffective treatment plan. Even in patients with biopsy-proven sarcoidosis, some image findings in isolation that may represent granulomatous infiltrates are disregarded as nonspecific without raising the possibility of sarcoidosis due to its rare occurrence. Here we discuss a case of multisystemic sarcoidosis in a 42-year-old female with a constellation of classic and rare findings of biopsy-proven sarcoidosis.

Imaging Features of Pediatric Sarcoidosis

Sarcoidosis is a granulomatous inflammatory disease of uncertain cause. It occurs most commonly in young and middle-aged adults and less frequently in children; therefore, few data on pediatric sarcoidosis exist in the literature. The diagnosis and management of sarcoidosis remain challenging because of diverse and often nonspecific clinical and imaging findings. In addition, the clinical picture varies widely by age. Prepubertal and adolescent patients often present with adult-like pulmonary disease; however, early-onset sarcoidosis is typically characterized by the triad of arthritis, uveitis, and skin rash. Sarcoidosis is mostly a diagnosis of exclusion made by demonstrating noncaseating granulomas at histopathologic examination in patients with compatible clinical and radiologic findings. Although sarcoidosis often affects the lungs and thoracic lymph nodes, it can involve almost any organ in the body. The most common radiologic manifestation is pulmonary involvement, characterized by mediastinal and bilateral symmetric hilar lymphadenopathies with perilymphatic micronodules. Abdominal involvement is also common in children and often manifests as hepatomegaly, splenomegaly, and abdominal lymph node enlargement. Although neurosarcoidosis and cardiac sarcoidosis are rare, imaging is essential to the diagnosis of central nervous system and cardiac involvement because of the risky biopsy procedure and its low diagnostic yield due to focal involvement. Being familiar with the spectrum of imaging findings of sarcoidosis may aid in appropriate diagnosis and management. ©RSNA, 2023 Test Your Knowledge questions are available in the supplemental material.

Granulomatous myopathy: Sarcoidosis and beyond

Non-necrotizing granulomatous inflammation is a rare but easily recognized histopathological finding in skeletal muscle biopsy. A limited number of diseases are known to be associated with non-necrotizing granulomatous myopathy. Once identified, a careful evaluation for evidence of extramuscular granulomatosis and other signs suggestive of sarcoidosis is warranted as about half of the patients have sarcoid myopathy. In addition, the presence of granulomatous myopathy should trigger a search for clinical and pathological clues of inclusion body myositis (IBM), which accounts for most of the remaining patients and can coexist with sarcoidosis. Recognizing the features of IBM in patients with granulomatous myopathy can potentially spare the patients from unnecessary exposure to immunosuppressive therapies. In patients whose granulomatous myopathy remain unexplained, further investigations should aim at identifying myasthenia gravis and other autoimmune disorders, especially those known to cause granulomatous inflammation in other organs. Laboratory investigations should include acetylcholine receptor, antimitochondrial, antineutrophil cytoplasmic, thyroglobulin, and thyroid peroxidase autoantibodies. In the appropriate clinical context, exposure to immune checkpoint inhibitors and chronic graft-vs-host disease can be causes of granulomatous myopathy. In cases of unexplained granulomatous myopathy, natural killer/T-cell lymphoma should be considered and careful histopathological examination for atypical cells and appropriate immunostaining is crucial. Identifying the etiology of granulomatous myopathy in each patient can guide appropriate treatment.

Acro-osteolysis: imaging, differential diagnosis, and disposition review

Acro-osteolysis is the osseous destruction of the hand or foot distal phalanges. The categories of the disease include terminal tuft, midshaft, or mixed types. Recognition of acro-osteolysis is straightforward on radiographs, but providing an accurate differential diagnosis and appropriately recommending advanced imaging or invasive tissue diagnosis can be more elusive. A radiologist's ability to provide advanced assessment can greatly aid clinicians in expedient diagnosis and management of the array of diseases presenting with acro-osteolysis.

Sarcoidosis, granulomas and myopathy syndromes: A clinical-pathology review

Muscle involvement in sarcoidosis is common by pathologic analysis, but symptomatic disorders are less frequent. Sarcoidosis-related muscle pathology includes non-caseating granulomas, muscle fiber changes that are diffuse or anatomically related to granulomas, and perimysial connective tissue with histiocyte-associated damage. The mechanisms by which granulomas form, enlarge and damage muscle tissues are incompletely understood. Sarcoidosis-related clinical syndromes with muscle involvement include: chronic myopathies with proximal weakness; nodular disorders; subacute onset disorders involving proximal or eye muscles; myalgia or fatigue syndromes; and, possibly, inclusion body myositis-like disorders. Corticosteroid treatment may benefit some syndromes, but clinical trials are necessary.

Distant migration of gel filler: imaging findings following breast augmentation

Recently, many attempts have been made to use injectable materials in the subcutaneous fat layer anywhere in the body, including the breast and face, for cosmetic purposes. A 56-year-old woman presented with multiple palpable lumps without tenderness or skin color changes on the anterior and lateral chest and the abdominal walls. Magnetic resonance imaging showed fluid-like collections without surrounding soft tissue inflammatory changes in the chest wall, abdominal wall, and deeper within the abdomen. The lesions penetrated the peritoneum and were observed adjacent to the liver dome. Ultrasonography also showed hypoechogenicity suggestive of fluid collection in the left axilla and trunk. The differential diagnosis based on radiologic findings included parasite manifestation, non-specific inflammatory conditions, and chronic granulomatous infections such as tuberculosis or non-tuberculous mycobacterial infections. However, these conditions are usually accompanied by changes in the adjacent subcutaneous fat layers, but our patient did not show any other abnormalities in the adjacent soft tissue. After biopsy and aspiration analysis, the patient was found to have a history of filler injection for breast augmentation approximately 17 years prior. It is often difficult to make a differential diagnosis without detailed knowledge of the patient's medical history. Here we describe a rare case of distant migration of the filler to the axilla, chest wall, abdominal wall, and peritoneum following breast augmentation with filler injection. Knowledge of the radiologic characteristics and migration patterns of gel fillers and their related complications is useful for making an accurate diagnosis.

Multiple bone lesions in a patient with fatigue: case report of bone sarcoidosis

Bone sarcoidosis is usually considered a rare manifestation of multisystemic sarcoidosis. With the growing use of more sensitive imaging techniques, such as ¹⁸F-FDG PET, the detection rate of bone involvement seems to be increasing. We describe the case of a woman presenting with fatigue and general malaise having multiple bone lesions on ¹⁸F-FDG PET. A broad range of differential diagnoses was considered, including malignancy, infections, metabolic diseases and primary bone tumours, which may have delayed the diagnosis. Diagnostic work-up eventually led to an anatomopathological diagnosis of bone sarcoidosis. Immunosuppressive therapy is often necessary since sarcoid bone lesions - even asymptomatic - generally appear in more extensive forms of the disease with other organ involvement.

Musculoskeletal Manifestations of Sarcoidosis

Since its initial description in the late 19th century, sarcoidosis has been extensively studied. Although the general mechanism of immune activation is known, many details especially in the context of disease associations are still missing. One of such associations is the musculoskeletal complications that are widely variable in terms of presentation and response to treatment. Sarcoidosis can involve the joints leading to acute and, less commonly chronic, arthritis. While acute arthritis is mostly self-resolving in nature, chronic arthritis may lead to deformity and destruction of the joint. Sarcoidosis can also involve the muscles, leading to different pathologies primarily categorized according to the clinical presentation, despite the efforts to find a new classification based on imaging, histological, and clinical findings. The bones can be directly and indirectly affected. Different types of bone lesions have been described, although around half of these patients remain asymptomatic. Osteoporosis, increased risk of fractures, hypercalcemia, and hypercalciuria are examples of the indirect effect of sarcoidosis on the bones, possibly contributed to elevated levels of calcitriol. Nevertheless, sarcoidosis can be associated with small-vessel, medium-vessel, and large vessel vasculitis, although it is frequently difficult to differentiate between the co-existence of a pure vasculitis and sarcoidosis and sarcoid vasculitis.

Imaging Spectrum of Calvarial Abnormalities

Calvarial abnormalities are usually discovered incidentally on radiologic studies or less commonly manifest with symptoms. This narrative review describes the imaging spectrum of the abnormal calvaria. The extent, multiplicity, and other imaging features of calvarial abnormalities can be combined with the clinical information to establish a final diagnosis or at least narrow the differential considerations. Prior trauma (congenital depression, leptomeningeal cysts, posttraumatic osteolysis), surgical intervention (flap osteonecrosis and burr holes), infection, and inflammatory processes (sarcoidosis) can result in focal bone loss, which may also be seen with idiopathic disorders without (bilateral parietal thinning and Gorham disease) or with (Parry-Romberg syndrome) atrophy of the overlying soft tissues. Anatomic variants (arachnoid granulations, venous lakes, parietal foramina) and certain congenital lesions (epidermoid and dermoid cysts, atretic encephalocele, sinus pericranii, and aplasia cutis congenita) manifest as solitary lytic lesions. Other congenital entities (lacunar skull and dysplasia) display a diffuse pattern of skull involvement. Several benign and malignant primary bone tumors involve the calvaria and manifest as lytic, sclerotic, mixed lytic and sclerotic, or thinning lesions, whereas multifocal disease is mainly due to hematologic or secondary malignancies. Metabolic disorders such as rickets, hyperparathyroidism, renal osteodystrophy, acromegaly, and Paget disease involve the calvaria in a more diffuse pattern. Online supplemental material is available for this article. ^©RSNA, 2021.

MRI and muscle imaging for idiopathic inflammatory myopathies

Although idiopathic inflammatory myopathies (IIM) are a heterogeneous group of diseases nearly all patients display muscle inflammation. Originally, muscle biopsy was considered as the gold standard for IIM diagnosis. The development of muscle imaging led to revisiting not only the IIM diagnosis strategy but also the patients' follow-up. Different techniques have been tested or are in development for IIM including positron emission tomography, ultrasound imaging, ultrasound shear wave elastography, though magnetic resonance imaging (MRI) remains the most widely used technique in routine. Whereas guidelines on muscle imaging in myositis are lacking here we reviewed the relevance of muscle imaging for both diagnosis and myositis patients' follow-up. We propose recommendations about when and how to perform MRI on myositis patients, and we describe new techniques that are under development.

Symptomatic nodular myopathy: an atypical presentation of sarcoidosis

Symptomatic myopathy is a very rare extrapulmonary manifestation of sarcoidosis that may not be readily recognised in the absence of a known history of sarcoid. Nodular myopathy is the most uncommon subtype of musclar sarcoidosis and, when encountered, establishing the diagnosis can be challenging. We present a case of symptomatic nodular myopathy as a first presentation of sarcoidosis in a young man who required a multidisciplinary approach to diagnose. The patient presented to our radiology department following a short period of flu-like illness and multiple soft tissue lesions. Biopsy of the lesions demonstrated noncaseating granulomata, and a diagnosis of sarcoidosis was established after important differential diagnoses were excluded. We present a literature review of sarcoid-related myopathy and the multimodality imaging characteristics of the different subtypes.

Myositis and myopathy of sarcoidosis: A case report

Muscular manifestations of sarcoidosis are commonly found on biopsy but rare on correlated imaging. We present a rare case of a 36-year-old male patient with sarcoid myositis and image findings of active myositis in the lower back and pelvic girdle musculature. This case suggests considering sarcoidosis as a differential diagnosis in the setting of chest findings and new lower back and lower extremity weakness.

Sarcoidosis, the master mimicker

Sarcoidosis is an idiopathic multisystem disorder characterized by noncaseating granulomas. The article focuses on the typical imaging manifestations of sarcoid and the common differentials that need to be included when appropriate. Mistaking a sarcoid-mimicking disease for sarcoid can result in increased patient morbidity and mortality. The pulmonary system is the most common system involved and is typically the best understood by the radiologist, however a deeper knowledge of the pulmonary findings and features of sarcoid in other organ systems is critical. There is a myriad of sarcoid imaging manifestations that can involve every organ system. Often a confidant diagnosis of sarcoid can be made, however a broad differential may need to be considered- differential diagnoses include primary neoplasm, metastatic disease, infectious, and inflammatory etiologies. Radiologist familiarity with the multimodality multisystem imaging findings of sarcoid can help guide clinical management and optimize patient care.

Prevalence, distribution and clinical significance of joints, muscles and bones in sarcoidosis: an 18F-FDG-PET/CT study

OBJECTIVES

In Sarcoidosis joints-muscles-bones (JMBs) localizations are of the least common. ¹⁸F-FDG-PET/CT imaging revolutionized detection of JMBs involvement by adding metabolic activity information and allowing for a comprehensive, whole-body mapping of the disease.

AIM AND METHODS

This study investigated prevalence, distribution, and clinical significance of JMBs sarcoidosis in 195 consecutive patients that underwent ¹⁸F-FDG PET/CT examination.

RESULTS

Joint and bone involvement were encountered in 15% of patients with a mean of the maximum-standardized-uptake-value (SUV_max) of 6.1. Most common location was the axial skeleton. Hypercalciuria was significantly more frequent in patients with osseous involvement (p = 0.003). Muscle activity (SUVmax = 2.4) was encountered in 20% of the patients, most frequently in treatment-naïve (p = 0.02). The muscles of the lower extremities were affected the most. Muscle and bone localization coexist in 50% of the cases. JMBs disease was almost asymptomatic, not related to chronicity but to pulmonary, nodal, and systemic disease. Long-term follow-up and treatment response of affected patients confirmed sarcoidosis.

CONCLUSION

¹⁸F-FDG-PET/CT revealed JMBs localizations and coexistence with other organ sites supporting the concept that sarcoidosis is a systemic disease. By allowing an integrative interpretation of multi-organ involvement in the context of a pattern highly suggestive of sarcoidosis, it strongly keeps-off the diagnosis of malignancy.

Dactylitis: A pictorial review of key symptoms

Dactylitis refers to a global swelling of a finger or a toe giving it a clinical sausage-shape presentation. It is an extremely suggestive symptom as it guides the rheumatologist towards a shortlist of diagnoses. However, radiologists are less familiar with dactylitis. The aim of this review is to detail and illustrate the main causes of dactylitis using standard X-ray imaging, ultrasound, computed tomography and magnetic resonance imaging in order to make radiologists more familiar with this symptom by illustrating the various conditions that are associated with dactylitis including infection, peripheral spondyloarthritis, sarcoidosis, microcrystalline deposition, osteoid osteoma, and sickle cell disease.

Resolution of Osseous Sarcoidosis with Methotrexate

Though a relatively uncommon manifestation of sarcoidosis, some clinicians are tasked with managing osseous involvement of disease, and the optimal treatment approach in this setting is not well established. Previous studies have shown variable efficacy for osseous sarcoidosis utilizing multiple agents alone or in combination, often using imaging follow-up in conjunction with clinical assessment to evaluate response to treatment. We present a case of widespread skeletal involvement of sarcoidosis without evidence of concurrent pulmonary disease demonstrating marked clinical improvement and near-complete resolution of imaging abnormalities on magnetic resonance imaging (MRI) following the use of methotrexate as the primary pharmacologic agent.

Retinal vasculitis with Chronic Recurrent Multifocal Osteomyelitis: a case report and review of the literature

Background

Concurrent presentation of retinal vasculitis with mixed sclerotic and lytic bone lesions is rare.

Case presentation

We present the case of a 37-year old woman with a several year history of episodic sternoclavicular pain who presented for rheumatologic evaluation due to a recent diagnosis of retinal vasculitis. We review the differential diagnosis of retinal vasculitis, along with the differential diagnosis of mixed sclerotic and lytic bone lesions. Ultimately, bone marrow biopsy confirmed diagnosis of chronic recurrent multifocal osteomyelitis (CRMO). Concurrent presentation of CRMO with retinal vasculitis is extremely rare but important to recognize. The patient demonstrated clinical response to prednisone and tumor necrosis factor-alpha inhibition (TNF-i).

Conclusion

This case reports and unusual presentation of CRMO spectrum disease involving the sternum and sternoclavicular joint with concurrent retinal vasculitis.

Multisystemic sarcoidosis-important lessons learnt from one of the great imitators

We report a case of a woman who was admitted with a suspicion of metastatic malignancy of unknown primary origin. A few months prior to her admission, she presented to a rheumatologist with acute anterior uveitis, psoriasiform rashes and polyarthritis. A diagnosis of psoriatic arthropathy was made and she was treated accordingly. Soon after she presented with persistent back and right upper quadrant abdominal pain for which she had a CT scan done with evidence of hilar lymphadenopathy, liver hypodensities and lytic-sclerotic bone lesions. She was referred to our hospital for further investigations and management. After re-exploring her clinical presentation and further investigations (including a liver biopsy), a diagnosis of multisystemic sarcoidosis with ocular, reticuloendothelial, hepatic and skeletal involvement was made. The patient was started on systemic glucocorticoids and second line immunosuppressants and demonstrated significant clinical improvement with resolution of her liver granulomata on imaging and improvement in her back pain. The case illustrates the importance of a thorough clinical assessment, review of investigations and an open mind in the evaluation of a patient.

Radiologic Manifestations of Musculoskeletal Sarcoidosis

PURPOSE OF REVIEW

The purpose of this review article is to present the spectrum of abnormalities and multi-modality imaging evaluations in patients with musculoskeletal sarcoidosis.

RECENT FINDINGS

The articular manifestations of sarcoidosis are difficult to distinguish from those of the other inflammatory and degenerative arthropathies, and the muscular lesions in sarcoidosis are generally clinically silent and therefore often missed. Magnetic resonance imaging has shown these manifestations to be very common in active sarcoidosis, and should thus be included in the screening if musculoskeletal sarcoidosis is suspected. The clinician should consider magnetic resonance imaging for the evaluation of patients with sarcoidosis who have unexplained osteoarticular complaints if standard radiographs are negative. Furthermore, radiologists should include sarcoidosis in the differential diagnosis of musculoskeletal disease detected at magnetic resonance imaging in the appropriate clinical setting.

Imaging Features of Soft-Tissue Calcifications and Related Diseases: A Systematic Approach

Soft-tissue calcification refers to a broad category of lesions. Calcifications are frequently identified by radiologists in daily practice. Using a simple algorithm based on the distribution pattern of the lesions and detailed clinical information, these calcified lesions can be systematically evaluated. The distribution pattern of the calcific deposits enables initial division into calcinosis circumscripta and calcinosis universalis. Using laboratory test results (serum calcium and phosphate levels) and clinical history, calcinosis circumscripta can be further categorized into four subtypes: dystrophic, iatrogenic, metastatic, and idiopathic calcification. This pictorial essay presents a systematic approach to the imaging features of soft-tissue calcifications and related diseases.

Radiological review of skull lesions

Abstract

Calvarial lesions are often asymptomatic and are usually discovered incidentally during computed tomography or magnetic resonance imaging of the brain. Calvarial lesions can be benign or malignant. Although the majority of skull lesions are benign, it is important to be familiar with their imaging characteristics and to recognise those with malignant features where more aggressive management is needed. Clinical information such as the age of the patient, as well as the patient’s history is fundamental in making the correct diagnosis. In this article, we will review the imaging features of both common and uncommon calvarial lesions, as well as mimics of these lesions found in clinical practice.

Teaching Points

• Skull lesions are usually discovered incidentally; they can be benign or malignant.

• Metastases are the most frequent cause of skull lesions.

• Metastatic lesions are most commonly due to breast cancer in adults and neuroblastoma in children.

• Multiple myeloma presents as the classic “punched out” lytic lesions on radiographs.

• Eosinophilic granuloma is an osteolytic lesion with bevelled edges.

Sarcoidosis from Head to Toe: What the Radiologist Needs to Know

Sarcoidosis is a multisystem granulomatous disorder characterized by development of noncaseating granulomas in various organs. Although the etiology of this condition is unclear, environmental and genetic factors may be substantial in its pathogenesis. Clinical features are often nonspecific, and imaging is essential to diagnosis. Abnormalities may be seen on chest radiographs in more than 90% of patients with thoracic sarcoidosis. Symmetric hilar and mediastinal adenopathy and pulmonary micronodules in a perilymphatic distribution are characteristic features of sarcoidosis. Irreversible pulmonary fibrosis may be seen in 25% of patients with the disease. Although sarcoidosis commonly involves the lungs, it can affect virtually any organ in the body. Computed tomography (CT), magnetic resonance imaging, and positron emission tomography/CT are useful in the diagnosis of extrapulmonary sarcoidosis, but imaging features may overlap with those of other conditions. Familiarity with the spectrum of multimodality imaging findings of sarcoidosis can help to suggest the diagnosis and guide appropriate management. ©RSNA, 2018.

HTLV‐1 seroprevalance in sarcoidosis. A clinical and laboratory study in northeast of Iran

Aim

Sarcoidosis is an autoimmune multiorgan granulomatosis disease with unknown origin. Some environmental factors such as viruses may induce the disease in genetically susceptible individuals. Human T cell lymphotropic virus type 1 (HTLV‐1) can dysregulate the human immune system and the role of this virus in the pathogenesis of autoimmune diseases has been investigated and documented, such as in uveitis. In this study, we have focused on the seroprevalence of HTLV‐1 in sarcoidosis in comparison to the normal population in the northeast of Iran, an endemic area for HTLV‐1.

Methods

This cross‐sectional study enrolled 125 patients with established sarcoidosis to evaluate the frequency of HTLV‐1 and compare it with the normal population of Mashhad, Iran. Participants’ blood samples were analyzed for HTLV‐1 antibody by an enzyme‐linked immunosorbent assay kit. Positive results were confirmed by polymerase chain reaction method. Finally, data were analyzed using SPSS 11.

Results

Among sarcoidosis patients 106 (84.8%) patients had a history of acute course and 19 (15.2%) had chronic sarcoidosis. Four percent of the patients versus 2.12% of the Mashhad population were HTLV‐1 positive with no statistical difference (P = 0.201). In age‐ and sex‐matched selected controls, 3.6% were HTLV‐1 positive again with no statistical difference by sarcoidosis group (P = 0.52). There was no statistical difference between arthritis, erythema nodusom, uveitis, constitutional symptoms, abnormal chest radiography (parahilar lymphadenopathy) and computed tomography scan findings, respiratory symptoms, sex, the course of the sarcoidosis in HTLV‐1 positive and negative sarcoidosis patients.

Conclusion

The frequency of HTLV‐1 in 125 sarcoidosis patients was 4%. In comparison with prevalence of HTLV‐1 in Mashhad, HTLV‐1 seroprevalence did not show any significant difference.

Paroxysmal cough and left sacroiliac joint pain in a 50-year-old Caucasian man

A 50-year-old Caucasian man who was a lifelong nonsmoker presented with a 3-year history of paroxysmal dry cough, fatigue, nonspecific myalgias, muscle weakness of the lower extremities and left sacroiliac joint pain. Initially, he was reviewed by a pulmonologist and subsequently he was referred to the Dept of Thoracic Medicine (Heraklion University Hospital, Heraklion, Greece) for further investigation. His medical history was remarkable for the presence of arterial hypertension on treatment with amlodipine and irbesartan.

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Craniofacial Manifestations of Systemic Disorders: CT and MR Imaging Findings and Imaging Approach

Many systemic diseases or conditions can affect the maxillofacial bones; however, they are often overlooked or incidentally found at routine brain or head and neck imaging performed for other reasons. Early identification of some conditions may significantly affect patient care and alter outcomes. Early recognition of nonneoplastic hematologic disorders, such as thalassemia and sickle cell disease, may help initiate earlier treatment and prevent serious complications. The management of neoplastic diseases such as lymphoma, leukemia, or Langerhans cell histiocytosis may be different if diagnosed early, and metastases to the maxillofacial bones may be the first manifestation of an otherwise occult neoplasm. Endocrinologic and metabolic disorders also may manifest with maxillofacial conditions. Earlier recognition of osteoporosis may alter treatment and prevent complications such as insufficiency fractures, and identification of acromegaly may lead to surgical treatment if there is an underlying growth hormone-producing adenoma. Bone dysplasias sometimes are associated with skull base foraminal narrowing and subsequent involvement of the cranial nerves. Inflammatory processes such as rheumatoid arthritis and sarcoidosis may affect the maxillofacial bones, skull base, and temporomandibular joints. Radiologists should be familiar with the maxillofacial computed tomographic and magnetic resonance imaging findings of common systemic disorders because these may be the first manifestations of an otherwise unrevealed systemic process with potential for serious complications. Online supplemental material is available for this article. ^©RSNA, 2018.

Muscular sarcoidosis involving the chest and abdominal walls: case report with MR imaging

Sarcoidosis is an inflammatory disorder that is characterized by the presence of noncaseating granulomas in tissues, involving many organs and tissues. Extra-pulmonary, especially muscular sarcoidosis is a rare condition. The most common location of the muscular sarcoidosis is known to be the proximal muscles of the extremities; however, there have been no cases of diffuse involvement of the chest and abdominal wall muscles. Here, we report a rare muscular sarcoidosis with infiltrative pattern in the chest and abdominal wall muscles and describe the MR imaging findings that were mistaken as lymphoma at initial diagnosis. Although our case did not show characteristic MR findings of muscular sarcoidosis, clinicians or radiologists who are aware of these imaging features can perform early systemic survey for sarcoidosis. Also muscle biopsy is very important to confirm the sarcoidosis and distinguish it from other tumors.

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.

MR Imaging of Atraumatic Muscle Disorders

Atraumatic disorders of skeletal muscles include congenital variants; inherited myopathies; acquired inflammatory, infectious, or ischemic disorders; neoplastic diseases; and conditions leading to muscle atrophy. These have overlapping appearances at magnetic resonance (MR) imaging and are challenging for the radiologist to differentiate. The authors organize muscle disorders into four MR imaging patterns: (a) abnormal anatomy with normal signal intensity, (b) edema/inflammation, (c) mass, and (d) atrophy, highlighting each of their key clinical and imaging findings. Anatomic muscle variants, while common, do not produce signal intensity alterations and therefore are easily overlooked. Muscle edema is the most common pattern but is nonspecific, with a broad differential diagnosis. Autoimmune, paraneoplastic, and drug-induced myositis tend to be symmetric, whereas infection, radiation-induced injury, and myonecrosis are focal asymmetric processes. Architectural distortion in the setting of muscle edema suggests one of these latter processes. Intramuscular masses include primary neoplasms, metastases, and several benign masslike lesions that simulate malignancy. Some lesions, such as lipomas, low-flow vascular malformations, fibromatoses, and subacute hematomas, are distinctive, but many intramuscular masses ultimately require a biopsy for definitive diagnosis. Atrophy is the irreversible end result of any muscle disease of sufficient severity and is the dominant finding in disorders such as the muscular dystrophies, denervation myopathy, and sarcopenia. This imaging-based classification, in correlation with clinical and laboratory data, will aid the radiologist in interpreting MR imaging findings in patients with atraumatic muscle disorders. ^©RSNA, 2018.

Ultrasound characterization of ankle involvement in Löfgren syndrome

BACKGROUND

Bilateral ankle arthritis is a classic diagnostic criterion for Löfgren syndrome. The objective of this study was to use ultrasonography to characterize the articular and periarticular involvement of the ankles in patients with Löfgren syndrome.

METHODS

Multicenter descriptive cohort study of patients with Löfgren syndrome who underwent ultrasonography of the ankles. We collected clinical data, imaging study findings, blood test results, and joint fluid properties in patients who underwent joint aspiration.

RESULTS

Findings from ultrasonography of the ankles in 40 patients were analyzed. The most common B-mode abnormality was subcutaneous edema (26/40), followed by tenosynovitis (22/40), with no differences in frequency across compartments. Joint involvement manifested as synovitis in 7 patients and effusion in 10 patients. Synovitis with increased vascularity by power Doppler was found in 3 patients. No statistically significant associations were found linking synovitis or tenosynovitis to clinical features (age and gender), laboratory tests, or imaging study findings.

CONCLUSION

Contrary to the classical view, our results indicate that ankle involvement in Löfgren syndrome is more often abarticular than articular. The inclusion of bilateral ankle arthritis among the diagnostic criteria for Löfgren syndrome deserves reappraisal.

Solitary subcutaneous sarcoidosis with massive chronic prepatellar bursal involvement

A 56-year-old man presented with a painless prepatellar mass of the left knee. MR images demonstrated a large, well-defined mass with heterogeneous intermediate signal intensity on T1- and proton density-weighted images. Mild, heterogeneous enhancement was noted after the intravenous administration of gadolinium. Diagnostic imaging included atypical soft-tissue infection, fibrogranulomatous reaction, gouty tophus, rheumatoid nodule and xanthoma or possibly malignancy. The histopathological examination revealed sarcoidosis involving the prepatellar bursa.

Fulminant musculoskeletal and neurologic sarcoidosis: case report and literature update

We report a case of fulminant sarcoidosis in a 28-year-old man presenting with skin nodules, multifocal small and large joint arthralgias, and blurred vision. Characteristic bone, soft tissue, articular, and CNS findings were evident on multimodality imaging. Bony abnormalities included near-complete destruction of a distal phalanx, "lace-like" lucent lesions, erosive arthritis, lytic lesions with and without sclerotic margins, and bone marrow replacement visible only on MRI. The extent of bony disease at time of presentation was unusual. We review the widely varying reported prevalence of imaging findings of bony sarcoidosis in the literature, and discuss reasons for this variability. We found that musculoskeletal findings at US and MRI were less specific than radiographic and CT findings, but were useful in quantifying extent of disease.

Diagnostic imaging of benign and malignant osseous tumors of the fingers

Primary lesions of the tubular bones of the digits are not uncommon, and the vast majority of these lesions are benign. Benign intramedullary lesions such as enchondromas are frequently discovered incidentally, unless they are associated with a pathologic fracture. Expansile lesions or lesions that are pedunculated and protrude from the cortex may manifest with pain and functional deficits from local inflammatory reactions. Systemic disorders such as sarcoidosis and local soft-tissue lesions with involvement of adjacent bone may mimic primary phalangeal bone tumors. Primary or secondary malignant lesions of the phalanges, most commonly chondrosarcomas, are extremely rare, and their characterization may require the use of multiple modalities, including radiography, computed tomography, and magnetic resonance imaging. Although ultrasonography is extremely useful in the evaluation of soft-tissue lesions of the hand, its role in the evaluation of osseous lesions is limited. The authors describe the imaging features of the most common benign osseous and chondral lesions of the fingers, including enchondromas, cystic lesions, and osteochondromas. In addition, they discuss malignant entities that may occur in the fingers (eg, chondrosarcomas and metastatic lesions) and commonly encountered mimics of primary osseous lesions (eg, glomus tumors, intraosseous epidermal inclusion cysts, infectious entities, and manifestations of systemic diseases). They also discuss the advantages and disadvantages of the most commonly used imaging modalities in differentiating benign from malignant lesions.