Pseudotumoural soft tissue lesions of the foot and ankle: a pictorial review

Treatments for Morton's neuroma

BACKGROUND

Morton's neuroma (MN) is a painful neuropathy resulting from a benign enlargement of the common plantar digital nerve that occurs commonly in the third webspace and, less often, in the second webspace of the foot. Symptoms include burning or shooting pain in the webspace that extends to the toes, or the sensation of walking on a pebble. These impact on weight-bearing activities and quality of life.

OBJECTIVES

To assess the benefits and harms of interventions for MN.

SEARCH METHODS

On 11 July 2022, we searched CENTRAL, CINAHL Plus EBSCOhost, ClinicalTrials.gov, Cochrane Neuromuscular Specialised Register, Embase Ovid, MEDLINE Ovid, and WHO ICTRP. We checked the bibliographies of identified randomised trials and systematic reviews and contacted trial authors as needed.

SELECTION CRITERIA

We included all randomised, parallel-group trials (RCTs) of any intervention compared with placebo, control, or another intervention for MN. We included trials where allocation occurred at the level of the individual or the foot (clustered data). We included trials that confirmed MN through symptoms, a clinical test, and an ultrasound scan (USS) or magnetic resonance imaging (MRI).

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodological procedures. We assessed bias using Cochrane's risk of bias 2 tool (RoB 2) and assessed the certainty of the evidence using the GRADE framework.

MAIN RESULTS

We included six RCTs involving 373 participants with MN. We judged risk of bias as having 'some concerns' across most outcomes. No studies had a low risk of bias across all domains. Post-intervention time points reported were: three months to less than 12 months from baseline (nonsurgical outcomes), and 12 months or longer from baseline (surgical outcomes). The primary outcome was pain, and secondary outcomes were function, satisfaction or health-related quality of life (HRQoL), and adverse events (AE). Nonsurgical treatments Corticosteroid and local anaesthetic injection (CS+LA) versus local anaesthetic injection (LA) Two RCTs compared CS+LA versus LA. At three to six months: • CS+LA may result in little to no difference in pain (mean difference (MD) -6.31 mm, 95% confidence interval (CI) -14.23 to 1.61; P = 0.12, I2 = 0%; 2 studies, 157 participants; low-certainty evidence). (Assessed via a pain visual analogue scale (VAS; 0 to 100 mm); a lower score indicated less pain.) • CS+LA may result in little to no difference in function when compared with LA (standardised mean difference (SMD) -0.30, 95% CI -0.61 to 0.02; P = 0.06, I2 = 0%; 2 studies, 157 participants; low-certainty evidence). (Function was measured using: the American Orthopaedic Foot and Ankle Society Lesser Toe Metatarsophalangeal-lnterphalangeal Scale (AOFAS; 0 to 100 points) - we transformed the scale so that a lower score indicated improved function - and the Manchester Foot Pain and Disability Schedule (MFPDS; 0 to 100 points), where a lower score indicated improved function.) • CS+LA probably results in little to no difference in HRQoL when compared to LA (MD 0.07, 95% CI -0.03 to 0.17; P = 0.19; 1 study, 122 participants; moderate-certainty evidence), and CS+LA may not increase satisfaction (risk ratio (RR) 1.08, 95% CI 0.63 to 1.85; P = 0.78; 1 study, 35 participants; low-certainty evidence). (Assessed using the EuroQol five dimension instrument (EQ-5D; 0-1 point); a higher score indicated improved HRQoL.) • The evidence is very uncertain about the effects of CS+LA on AE when compared with LA (RR 9.84, 95% CI 1.28 to 75.56; P = 0.03, I2 = 0%; 2 studies, 157 participants; very low-certainty evidence). Adverse events for CS+LA included mild skin atrophy (3.9%), hypopigmentation of the skin (3.9%) and plantar fat pad atrophy (2.6%); no adverse events were observed with LA. Ultrasound-guided (UG) CS+LA versus non-ultrasound-guided (NUG) CS+LA Two RCTs compared UG CS+LA versus NUG CS+LA. At six months: • UG CS+LA probably reduces pain when compared with NUG CS+LA (MD -15.01 mm, 95% CI -27.88 to -2.14; P = 0.02, I2 = 0%; 2 studies, 116 feet; moderate-certainty evidence). (Assessed with a pain VAS.) • UG CS+LA probably increases function when compared with NUG CS+LA (SMD -0.47, 95% CI -0.84 to -0.10; P = 0.01, I2 = 0%; 2 studies, 116 feet; moderate-certainty evidence). We do not know of any established minimum clinical important difference (MCID) for the scales that assessed function, specifically, the MFPDS and the Manchester-Oxford Foot Questionnaire (MOXFQ; 0 to 100 points; a lower score indicated improved function.) • UG CS+LA may increase satisfaction compared with NUG CS+LA (risk ratio (RR) 1.71, 95% CI 1.19 to 2.44; P = 0.003, I2 = 15%; 2 studies, 114 feet; low-certainty evidence). • HRQoL was not measured. • UG CS+LA may result in little to no difference in AE when compared with NUG CS+LA (RR 0.42, 95% CI 0.12 to 1.39; P = 0.15, I2 = 0%; 2 studies, 116 feet; low-certainty evidence). AE included depigmentation or fat atrophy for UG CS+LA (4.9%) and NUG CS+LA (12.7%). Surgical treatments Plantar incision neurectomy (PN) versus dorsal incision neurectomy (DN) One study compared PN versus DN. At 34 months (mean; range 28 to 42 months), PN may result in little to no difference for satisfaction (RR 1.06, 95% CI 0.87 to 1.28; P = 0.58; 1 study, 73 participants; low-certainty evidence), or for AE (RR 0.95, 95% CI 0.32 to 2.85; P = 0.93; 1 study, 75 participants; low-certainty evidence) compared with DN. AE for PN included hypertrophic scaring (11.4%), foreign body reaction (2.9%); AE for DN included missed nerve (2.5%), artery resected (2.5%), wound infection (2.5%), postoperative dehiscence (2.5%), deep vein thrombosis (2.5%) and reoperation with plantar incision due to intolerable pain (5%). The data reported for pain and function were not suitable for analysis. HRQoL was not measured.

AUTHORS' CONCLUSIONS

Although there are many interventions for MN, few have been assessed in RCTs. There is low-certainty evidence that CS+LA may result in little to no difference in pain or function, and moderate-certainty evidence that UG CS+LA probably reduces pain and increases function for people with MN. Future trials should improve methodology to increase certainty of the evidence, and use optimal sample sizes to decrease imprecision.

Soft Tissue Sarcomas Mimicking Benign Inflammatory Processes: A Diagnostic Dilemma

Background

Soft tissue sarcomas are rare and often go undetected until a later stage, particularly when they present as intra-articular or tenosynovial lesions mimicking benign synovial pathologies. The failure to distinguish between malignant and benign synovial disease can have a significant impact on patient outcomes and limit alternatives for local control surgery and limb salvage.

Case Description

In this case series, we present two cases of soft tissue sarcomas, one being an intraarticular synovial chondrosarcoma, and the other a pleomorphic spindle cell sarcoma centred along tendon sheaths. Radiologically, the initial clinical presentation of these cases resembled benign synovial pathologies, leading to a delay in diagnosis and treatment.

Conclusion

Our study underscores the importance of maintaining a low threshold of suspicion for surveillance, a multidisciplinary approach, and early histological diagnosis to ensure appropriate timely treatment and a favourable prognosis for patients with soft tissue sarcomas.

Differential Diagnosis of Metatarsalgia

Lesser (or central) metatarsalgia is defined as pain in the forefoot under or around the lesser metatarsals and their respective metatarsophalangeal joints. Two common causes of central metatarsalgia are Morton's neuroma (MN) and plantar plate (PP) injury. Because both clinical and imaging features overlap, establishing the correct differential diagnosis may be challenging. Imaging has a pivotal role in the detection and characterization of metatarsalgia. Different radiologic modalities are available to assess the common causes of forefoot pain, so the strengths and weakness of these imaging tools should be kept in mind. It is crucial to be aware of the pitfalls that can be encountered in daily clinical practice when dealing with these disorders. This review describes two main causes of lesser metatarsalgia, MN and PP injury, and their differential diagnoses.

Imaging of Tendinous and Muscular Anatomical Variants Around the Ankle

Tendinous and muscular anatomical variants around the ankle are usually an unexpected finding on imaging. Magnetic resonance imaging offers the best visualization of the accessory muscles; however, they can also be detected on radiography, ultrasonography, and computed tomography. Their accurate identification facilitates appropriate management of the rare symptomatic cases, mostly caused by accessory muscles in the posteromedial compartment. Symptomatic patients present with chronic ankle pain, most commonly as tarsal tunnel syndrome. The most frequently observed accessory muscle around the ankle is the peroneus tertius muscle, an accessory muscle in the anterior compartment. The tibiocalcaneus internus and peroneocalcaneus internus are uncommon; anterior fibulocalcaneus is rarely mentioned. We describe the anatomy of the accessory muscles with their anatomical relations accompanied by schematic drawings and radiologic images from clinical practice.

Presurgical Perspective and Posttreatment Evaluation of Soft Tissue Tumors of the Ankle and Foot in Adults

This article discusses soft tissue tumors of the ankle and foot region in adults, including tumors of the joints, and also briefly addresses tumor-simulating lesions. We offer general recommendations and describe specific aspects of common entities in that region, such as typical imaging appearance, therapeutic strategies, and posttherapeutic considerations. Focal masses and diffuse swelling are common in the foot and ankle region; most of them are non-neoplastic. Some of the tumors, such as plantar fibromatosis, tenosynovial giant cell tumor, synovial chondromatosis, or schwannoma, have a very typical appearance on magnetic resonance imaging. Sarcomas are rare among true soft tissue tumors; however, they can be small and well demarcated, may grow slowly, and are often misinterpreted as benign. This is especially true for synovial sarcoma, one of the most common sarcomas in this region. Densely packed tissues in the foot and ankle may hamper determining the tissue of origin. Adherence to diagnostic guidelines and cooperation with tumor centers is crucial including for posttherapeutic surveillance. We also describe typical posttherapeutic changes and complications after surgery, radiation therapy, and chemotherapy, as well as parameters for the detection and exclusion of recurrence of soft tissue tumors of the ankle and foot.

Postoperative clinical and functional outcomes in patients with tumor and tumor-like lesion of foot and ankle

Background

Tumors and tumor-like lesions of the foot and ankle are relatively rare and their postoperative clinical outcome has not been well reported.

Methods

This study retrospectively reviewed medical records of all patients who underwent excision of tumors and tumor-like lesions of the foot and ankle from 2008 to 2020. Preoperative and postoperative clinical outcomes were evaluated by the Japanese Society for Surgery of the Foot (JSSF) scales (pain, function, and alignment).

Results

A total of 117 consecutive patients were analyzed in this study. Bone lesions accounted for 51 patients (benign: 45, intermediate malignancy: 1, malignant: 5), and soft tissue lesions accounted for 66 patients (benign: 57, intermediate malignancy: 2, malignant: 7). Four patients (8%) presenting with bone tumor and six (9%) soft tissue tumors resulted in recurrence. Eight (67%) patients with malignant lesions were alive continuously disease free and followed for a median of 50.5 (range: 18 to 82) months. Amputation at the first operation was done for five cases (33%) of malignant or intermediate malignancy (below-knee amputation: 1, Chopart disarticulation: 1, forefoot amputation: 3). Postoperative JSSF scores resulted in a significant 'positive' increase (bone lesion, 75.9 ± 13.7 to 91.4 ± 14.9, p < 0.001; soft tissue lesion, 84.7 ± 14.8 to 91.9 ± 12.5, p < 0.001). The score improvement in bone lesions was significantly higher than in soft tissue lesions (p = 0.003).

Conclusion

The surgical management of tumors and tumor-like lesions of the foot and ankle showed good post-operative functional outcomes with bone lesions exhibiting better results when compared to soft-tissue lesions.

Cystic Degeneration of an Atypical Adventitial Bursitis: Case Report and Literature Review

Adventitial (adventitious) bursae occur as a pathological condition in areas between soft tissues and bone where abnormal friction arises due to professional, traumatic, or sport activity. An atypical localization of an adventitial bursa was noticed on the ulnar margin of the distal forearm in a woman with a mild bone misalignment, as a professional disorder. The clinical presentation was one of subcutaneous mass with mild pain and no local signs of inflammation. A 1-year follow-up visit noted the degeneration of the bursa into a cystic lesion, as proved with a grayscale sonogram, using a 14 MHz linear transducer. This was an unexpected chronic evolution. A quick literature search found either resolution or a chronic course with complications as fibrosis, infection, and ulceration of adventitial bursitis.

Predicting Forefoot-Orthosis Interactions in Rheumatoid Arthritis Using Computational Modelling

Foot orthoses are prescribed to reduce forefoot plantar pressures and pain in people with rheumatoid arthritis. Computational modelling can assess how the orthoses affect internal tissue stresses, but previous studies have focused on a single healthy individual. This study aimed to ascertain whether simplified forefoot models would produce differing biomechanical predictions at the orthotic interface between people with rheumatoid arthritis of varying severity, and in comparison to a healthy control. The forefoot models were developed from magnetic resonance data of 13 participants with rheumatoid arthritis and one healthy individual. Measurements of bony morphology and soft tissue thickness were taken to assess deformity. These were compared to model predictions (99th% shear strain and plantar pressure, max. pressure gradient, volume of soft tissue over 10% shear strain), alongside clinical data including body mass index and Leeds Foot Impact Scale–Impairment/Footwear score (LFIS-IF). The predicted pressure and shear strain for the healthy participant fell at the lower end of the rheumatoid models’ range. Medial first metatarsal head curvature moderately correlated to all model predicted outcomes (0.529 < r < 0.574, 0.040 < p < 0.063). BMI strongly correlated to all model predictions except pressure gradients (0.600 < r < 0.652, p < 0.05). There were no apparent relationships between model predictions and instances of bursae, erosion and synovial hypertrophy or LFIS-IF score. The forefoot models produced differing biomechanical predictions between a healthy individual and participants with rheumatoid arthritis, and between individuals with rheumatoid arthritis. Models capable of predicting subject specific biomechanical orthotic interactions could be used in the future to inform more personalised devices to protect skin and soft tissue health. While the model results did not clearly correlate with all clinical measures, there was a wide range in model predictions and morphological measures across the participants. Thus, the need for assessment of foot orthoses across a population, rather than for one individual, is clear.

Hemorrhagic Synovitis of the First Metatarsophalangeal Joint: A Case Report

CASE

A 69-year-old woman presented with a painful mass at her first metatarsophalangeal joint. Further evaluation was concerning for a neoplastic process, leading to surgical intervention. Pathological examination demonstrated hemosiderotic synovitis, and hematologic evaluation led to a new diagnosis of von Willebrand disease.

CONCLUSION

Hemorrhagic synovitis, involving mostly larger joints, has been well described. However, a literature search demonstrates no cases of this in the foot or toes. Presentation of hemarthroses and underlying coagulopathies can be subtle and must be considered in patients presenting with soft-tissue masses or pseudotumors, despite having no previous diagnosis.

Heel fat pad involvement in rheumatoid arthritis: a review and case series

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease affecting not only the synovial joints but also multiple extra-articular sites, including ankle and foot soft tissue. Hindfoot abnormalities usually follow those in the forefoot, with up to 4 out of 10 patients experiencing talalgia during their disease course. Enthesophytosis, retrocalcaneal bursitis, and plantar fasciitis are among the most common etiologies, while heel fat pad abnormalities like subcalcaneal bursitis are rare. Here, we report two cases of subcalcaneal bursitis, and the first case of heel fat pad and subcalcaneal bursa herniation in patients with established RA, along with a comprehensive literature review of subcalcaneal bursitis and other heel fat pad abnormalities in RA. Subcalcaneal bursitis, also referred to as panniculitis, inflammatory-edematous lesion, or adventitial (adventitious) bursitis has been reported in up to 10% of patients with RA. It appears as a compressible, heterogeneous, and hypoechoic subcalcaneal mass on ultrasound (US), with peripheral vascularization on Doppler US. Patients may present with heel discomfort. Ultrasonographic assessment is usually sufficient to confirm the presence of heel fat pad pathologies. Rest, analgesics, and mechanical aids with or without addition of disease-modifying antirheumatic drugs are usually employed, while intervention is rarely required.

Lesions of the heel fat pad

OBJECTIVE

The heel fat pad (HFP) is a specialized soft tissue structure formed of adipose tissue that overlies the inferior and posterior aspect of the calcaneus and provides the cushioning effect of the heel. Lesions of the HFP are rare and can be a cause of debilitating heel pain that may often pose a challenge to clinicians. This study provides a series of lesions identified within the HFP.

METHODS AND MATERIALS

A retrospective review of heel pad lesions over a 12 year period was conducted at our tertiary orthopaedic oncology centre. All lesions of the heel fat pad were included in the study. Plantar fasciitis was excluded.

RESULTS

There were 17 heel pad lesions identified, of which the majority (n = 15) were benign.

CONCLUSION

We highlight a wide spectrum of pathologies that can occur in the HFP. Although rare, clinicians should be aware of these lesions, to initiate appropriate management.

Increased frequency of intermetatarsal and submetatarsal bursitis in early rheumatoid arthritis: a large case-controlled MRI study

Background

The forefoot is a preferential location for joint and tendon sheath inflammation in rheumatoid arthritis (RA). It also contains bursae, of which the intermetatarsal bursae have a synovial lining. Some small imaging studies suggested that intermetatarsal bursitis (IMB) and submetatarsal bursitis (SMB) are involved in RA, but their association has not been thoroughly explored. Healthy control studies suggested that lesion size might be relevant. We studied the relation between IMB and SMB in early RA, compared to other arthritides and healthy controls, and the relevance of lesion sizes.

Methods

Six hundred and thirty-four participants were studied: 157 consecutive patients presenting with early RA, 284 other arthritides, and 193 healthy controls. All underwent unilateral contrast-enhanced MRI of the forefoot at presentation. Two readers independently scored IMB and SMB and measured transverse and dorsoplantar diameters, blinded to clinical data. Subsequently, consensus was reached. Intra-reader ICC was 0.89. Logistic regression models were used, and test characteristics were calculated.

Results

IMB and SMB associated with RA independent of each other (P < 0.001) and independent of age, gender, BMI, RA-MRI inflammation, and anti-CCP-antibodies (P = 0.041). Sensitivity for RA of IMB was 69%, and for SMB 25%. Specificity for IMB was 70% compared to other arthritides, and 84% compared to healthy controls. For SMB, this was 94% and 97% respectively. Regarding lesion size, the groups had considerable overlap: no cut-off size for RA could be distinguished with high sensitivity and specificity.

Conclusion

Intermetatarsal and submetatarsal bursitis associated with early rheumatoid arthritis, contributing to the emerging evidence that inflammation of juxta-articular soft tissues is an early feature of RA.

Adventitious bursitis in the plantar fat pad of forefoot presenting as a tumoral mass

Adventitious bursitis of the plantar fat pad is a common cause of forefoot pain. It may develop at sites where subcutaneous tissue is exposed to friction and high pressure. In the forefoot, adventitious bursitis is usually adjacent to bony prominences of the metatarsal heads. Diagnosis and management of adventitious bursitis usually do not require imaging studies. However, the condition occasionally presents as a solid pseudotumoral mass requiring imaging. Magnetic resonance imaging (MRI) may demonstrate a heterogeneous mass with a solid component exhibiting intermediate to high signal intensity on T2-weighted images and thick nodular enhancement suggesting a neoplastic lesion. We report three cases of adventitious bursitis in patients who complained of a painful palpable mass on the forefoot, with a partially solid and enhancing component seen on MRI. In the first case, a biopsy was performed for the diagnosis of adventitious bursitis. The two other cases exhibited a solid component on MRI. However, a diagnosis of adventitious bursitis was suspected, and it was felt that a biopsy could be postponed. The spontaneous regression of the mass with relative discharge of the forefoot pressure confirmed the diagnosis. With these three cases, we illustrate the MR findings that could suggest adventitious bursitis despite the presence of a solid component and that may obviate the need for pathologic proof.

Sonographic diagnosis of clinically unsuspected thrombosis of the medial marginal vein and dorsal arch of the foot

Foot pain is common in daily clinical practice but thrombosis of the foot veins is rarely considered as a differential diagnosis. Several cases of plantar veins thrombosis are reported in literature but a detailed description of ultrasonographic findings in case of thrombosis of the dorsal venous arch of the foot is lacking. We report a case of ours with a thrombosis of the medial marginal vein and dorsal venous arch of the foot, showing its close anatomical relation with the extensor hallucis longus tendon.

Forefoot Pain in the Lesser Toes: Anatomical Considerations and Magnetic Resonance Imaging Findings

Various conditions may result in forefoot pain. Magnetic resonance (MR) imaging allows accurate assessment of many of these conditions. We provide an overview of forefoot disorders divided into bones, capsule and plantar plate, musculotendinous structures, neurovascular structures, and subcutaneous tissue. We review normal anatomical features as well as MR imaging findings of common disorders.

Ultrasound features of sole of foot pathology: a review

Foot pain is a common problem among adults, with approximately 19% of men and 25% of women describing significant daily foot pain that limits their ability to function. Older adults, the obese, and active adults participating in sports involving running and jumping are at increased risk of developing pathology. Problems affecting the sole of the foot are often the cause of pain. Ultrasound is an extremely useful method of quickly and accurately localizing and characterizing pathology of the foot. The wide availability of ultrasound combined with its low cost, lack of ionizing radiation, high spatial resolution, multiplanar capability and excellent patient tolerance makes it an ideal technique for assessing the superficial structures in the sole of the foot. Ultrasound has the advantage of dynamic assessment over other imaging modalities. Furthermore, Doppler interrogation allows a real-time assessment of vascularity, not possible using other techniques. The ability to perform extended field of view images allows improved image presentation, which has increased clinicians' acceptance of the technique. Finally, ultrasound can be used to guide interventional procedures. This review article will consider the ultrasound features of pathology commonly affecting the sole of the foot, and will describe MRI correlates that can be expected.

Foot pain is a common problem among adults, with approximately 19% of men and 25% of women describing significant daily foot pain that limits their ability to function. Older adults, the obese, and active adults participating in sports involving running and jumping are at increased risk of developing pathology. Problems affecting the sole of the foot are often the cause of pain. Ultrasound is an extremely useful method of quickly and accurately localizing and characterizing pathology of the foot. The wide availability of ultrasound combined with its low cost, lack of ionizing radiation, high spatial resolution, multiplanar capability and excellent patient tolerance makes it an ideal technique for assessing the superficial structures in the sole of the foot. Ultrasound has the advantage of dynamic assessment over other imaging modalities. Furthermore, Doppler interrogation allows a real-time assessment of vascularity, not possible using other techniques. The ability to perform extended field of view images allows improved image presentation, which has increased clinicians’ acceptance of the technique. Finally, ultrasound can be used to guide interventional procedures. This review article will consider the ultrasound features of pathology commonly affecting the sole of the foot, and will describe MRI correlates that can be expected.

MRI imaging of soft tissue tumours of the foot and ankle

The majority of soft tissue lesions in the foot and ankle are benign. The aim of this review is to provide the reader with a comprehensive overview of the magnetic resonance imaging (MRI) characteristics of the most common benign and malignant soft tissue neoplasms which occur around the foot and ankle. This should enable the reader to formulate a reasonable differential diagnosis and, most importantly, to recognise those rare aggressive lesions that require further assessment and tissue biopsy.

Role of imaging methods in diagnosis and treatment of Morton's neuroma

Among the many causes of forefoot pain, Morton's neuroma (MN) is often suspected, particularly in women, due to its high incidence. However, there remain controversies about its relationship with symptomatology and which diagnostic and treatment choices to choose. This article mainly focuses on the role of the various imaging methods and their abilities to support an accurate diagnosis of MN, ruling out other causes of forefoot pain, and as a way of providing targeted imaging-guided therapy for patients with MN.

Unusual Presentation of Foreign Body Granuloma of the Foot After Sharp Injury Mimicking a Malignant Lesion: A Case Report

Foot foreign body granulomas can mimic malignancies, especially when the history and unusual location pose a diagnostic dilemma. We report the case of a 33-year-old male with delayed-onset progressive swelling over the foot dorsum after a sharp injury through the plantar aspect of the foot. The unusual presentation and radiolucency warranted further radiologic evaluation, which revealed a benign foot swelling. An excision biopsy and histopathologic examination revealed a rubber body granuloma. No recurrence of the granuloma was noted during the 11-month follow-up period after removal of the offending agent. The nature of the injury, immunologic response to the rubber fragment, and lack of infection led to the delayed presentation at an unusual site, mimicking malignancy. Rubber body granuloma has rarely been reported in published studies. A high index of suspicion of retained radiolucent fragments and astute radiologic evaluation with magnetic resonance imaging are required for management of sharp injuries occurring through footwear. We reviewed the approach for evaluating such cases of foot swelling that can mimic malignancies.

Benign and malignant tumors of the foot and ankle

Pain and focal masses in the foot and ankle are frequently encountered and often initiate a workup including imaging. It is important to differentiate benign lesions from aggressive benign or malignant lesions. In this review, multiple examples of osseous and soft tissue tumors of the foot and ankle will be presented. Additionally, the compartmental anatomy of the foot and ankle will be discussed in terms of its relevance for percutaneous biopsy planning and eventual surgery. Finally, a general overview of the surgical management of benign, benign aggressive and malignant tumors of the foot and ankle will be discussed.

Cutaneous Metaplastic Synovial Cyst: A Case Report

Cutaneous metaplastic synovial cyst (CMSC), presents as a solitary, tender subcutaneous nodule that usually occurs at the site of previous surgery or trauma. Histologically, the lesion is characterized by a cystic structure with villous-like projections that lined by metaplastic synovial tissue. The main cause remains unclear, but trauma is presumed to be a precipitating factor, as most reported cases have a history of antecedent cutaneous injury. Here we present a case of CMSC in a 51 year old man, presented with a painless deep-seated dermal nodule in the medial aspect of left ankle without history of any trauma or surgery in this site. Immuno-histochemistry study reveals positive reaction for CD68 in the cystic wall and negative reactions for S-100. CMSC is a unique lesion and worthy to attention, and should be included in the differential diagnosis of deep dermal cutaneous cysts.

Synovial sarcoma: Magnetic resonance and computed tomography imaging features and differential diagnostic considerations

The present study retrospectively examined 24 cases of pathologically confirmed synovial sarcoma and analyzed the clinical presentation and imaging findings in order to explore the imaging features of synovial sarcoma. The majority of the lesions were large (>5 cm; 88%), rounded or lobulated, relatively well-defined tumor masses in the extremities near the joints or deeply located. On computed tomography (CT) scans, the lesions demonstrated intensity signals similar to those of muscle. Six cases exhibited punctate calcification in the periphery of the tumor. On T1-weighted images, the largest lesions of >5 cm, were usually heterogeneous, with a signal intensity similar to or slightly higher than that of muscle. On T2-weighted images, heterogeneous high-intensity or slightly high-intensity signals were observed, with 12 cases exhibiting a high signal consistent with hemorrhage and 12 presenting signals that indicated internal septations. Contrast-enhanced scanning revealed heterogeneous enhancement in the majority of the lesions and no enhancement in areas of cystic necrosis or internal septations. Synovial sarcoma has specific imaging features, and comprehensive analysis of CT and magnetic resonance imaging can improve the accuracy of the pre-operative diagnosis.

Soft tissue swellings in the foot: rheumatoid nodulosis

Background rheumatoid nodulosis is a rare disease characterised by multiple subcutaneous nodules, a high titre of rheumatoid factor, radiologically detectable cystic bone lesions, but with none or few of the systemic manifestations or joint activity of rheumatoid disease. Histopathologically, nodulosis is the same as the nodules found in rheumatoid arthritis. It is considered to be a benign variant of rheumatoid arthritis. A 69 year old male presents with multiple subcutaneous nodules on the feet. This case study highlights the benefits of ultrasound in establishing a correct diagnosis and management. Although rare, rheumatoid nodulosis is a consideration in the differential diagnoses of soft tissue swellings in the feet.

Forefoot: a basic integrated imaging perspective for radiologists

Imaging of the forefoot is increasingly requested for patients with metatarsalgia. Awareness with specific anatomic arrangements exclusive for the forefoot and widely variable pathologic entities associated with metatarsalgia helps the radiologist to tailor a cost-effective imaging approach. This will enable reaching a specific diagnosis as much as possible with subsequent proper patient management. This pictorial review aims to provide basic understanding for the different imaging modalities used in studying the forefoot. After that, certain anatomic arrangements exclusive for the forefoot are discussed. The final section of this review describes the imaging findings of some common forefoot problems.

Human papillomavirus-associated plantar epidermoid cysts: MR and US imaging appearance

Epidermoid cysts are epithelial cysts that present as slow-growing intradermal or subcutaneous lesions. While recent epidemiological studies have isolated human papillomavirus (HPV) from plantar epidermoid cysts, imaging findings in HPV-associated epidermoid cysts have not been previously reported. We describe imaging findings in two patients with HPV-associated plantar epidermoid cysts. Magnetic resonance (MR) imaging and ultrasonography (US) showed linear arrangement of several adjacent globular cysts. This appearance is hypothesized to result from HPV-associated eccrine duct metaplasia leading to cyst formation and later traumatic rupture leading to formation of multiple adjacent cystic components. It may be useful to suggest assessing the presence of HPV antigen in plantar lesions having these imaging findings.

Lumps and bumps around the foot and ankle: an assessment of frequency with ultrasound and MRI

Benign and malignant tumours and tumour-like conditions frequently present as lumps in the foot and ankle. Although definitive histological diagnosis cannot be ascertained short of a biopsy, most entities can be confidently characterised on ultrasound and/or MRI. Masses in the foot and ankle present with lump, pain, paraesthesia, restricted mobility or a combination of these. In this review we have focussed on the relative frequency of masses in the foot and ankle that present as focal lumps, with a brief description of their typical appearance on ultrasound and MRI. Ganglions were the largest group in our series representing 24 % of the masses, followed by tendon- and ligament-related lesions and, bony lesions representing 16 % and 11 % of the masses respectively.

Grading and characterization of soft tissue tumors on magnetic resonance imaging: the value of an expert second opinion report

Objective

To retrospectively compare the accuracy of the initial MRI (magnetic resonance imaging) report of referring radiologists and the second opinion report.

Material and methods

MRI of 155 patients presenting with a soft tissue tumor (STT) in a single large community center were referred for inclusion in the Belgian Soft Tissue Neoplasm Registry (BSTNR). The initial report and the second opinion report were made independently. Histopathology (gold standard) was obtained in 90 patients (group 1). In 65 patients, the diagnosis was made by the combination of clinical findings and/or follow-up (group 2). In group 1, the concordance in grading and tissue-specific (TS) diagnosis between the referring center (RC) and expert center (EC) was reviewed.

Results

In group 1, MR grading yields a sensitivity of 100% and a specificity of 89% in the EC. The sensitivity was 88% and the specificity 81% in the RC. The accuracy was significantly higher in the EC (92%) compared to the RC (83%) (p = 0.039). The TS diagnosis was correct in 50% versus 38.5% of malignant tumors and in 71.8% versus 51.6% of benign tumors in the EC and RC respectively.

Conclusion

A second opinion report increases the accuracy in the diagnosis of STT on MRI.

Main Messages

• A second opinion MRI report increases the overall accuracy in the diagnosis of soft tissue tumors.

• There is a good overall agreement in MR grading between the referring and expert institution.

• In the expert center, there were fewer false-negative and false-positive diagnoses.

• MRI performs better in the tissue-specific diagnosis of benign versus malignant STT.