Imaging of soft tissue lesions of the foot and ankle

Periarticular calcifications

Periarticular calcification and ossification is a frequent finding on imaging and may sometimes pose a diagnostic challenge. The differential diagnoses for this radiological finding are wide and can be classified into broad groups such as idiopathic, developmental, trauma, burns, infection, tumor, connective tissue disease, crystalline, metabolic, vascular, and foreign bodies. With careful consideration of the clinical and imaging findings as well as awareness of mimickers of periarticular mineralization, the list of differential diagnoses can be narrowed down. This article aims to review the clinical-radiologic findings of periarticular calcified or ossified lesions with relevant imaging illustrations.

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.

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.

Is Histopathological Analysis of Interdigital Morton's Neuroma Necessary?

BACKGROUND

Interdigital neuroma (IN), otherwise known as Morton's neuroma, is a common cause of metatarsalgia presenting to the elective foot and ankle clinic. Surgical excision of the IN in patients who fail to respond to nonoperative measures is considered to be the gold standard of care in many centers. The Royal College of Pathologists UK recommend that all excised interdigital Morton's neuromas are sent for formal histopathological analysis. We present a study correlating clinical and radiological diagnosis with histopathologic appearances of IN following surgical excision, and question if routine histopathological analysis is warranted.

METHODS

A retrospective study was carried out in a single center. Ninety-six operative records were reviewed to identify all the cases of IN surgically resected between January 2007 and July 2016. The histopathology result of the resected IN specimen, that had a clinical and radiological diagnosis of IN, was analyzed.

RESULTS

A total of 85 patients met the inclusion criteria and were included in the final analysis. We found that 100% of patients with a clinical, radiographic, and intraoperative diagnosis of a Morton's neuroma had a histopathological report confirming a Morton's interdigital neuroma.

CONCLUSION

In our single-surgeon series, histopathologic diagnosis is in complete agreement with clinical and radiological diagnosis. We therefore recommend that routine histopathological analysis of IN is not necessary, saving resources and providing a cost benefit. Histopathologic examination should be reserved only in cases where intraoperative findings do not concur with clinical and radiological features.

LEVELS OF EVIDENCE

Level IV: Case series.

The magnetic resonance appearance of surfers' knots: a case report

Athletes are at increased risk of developing soft-tissue lesions of the lower limbs. Although the majority of these will be benign, the differential diagnosis is broad and increasingly, doctors are turning to magnetic resonance imaging (MRI) as a first-line investigation when presented with these sorts of lesions, both to narrow the differential diagnosis and exclude malignancy. We report the case of a 28-year-old Caucasian man who presented with 2 soft-tissue lesions of the right foot. History and examination of the nodules fitted with a diagnosis of surfers' knots, an unusual form of acquired, benign, connective tissue nodule that may appear over the tibial tuberosities, dorsum of the feet, and occasionally on the chest of surfers in association with repetitive microtrauma during surfing. MRI findings were consistent with this diagnosis with both lesions exhibiting T1 hypointensity and speckled T2 hypointensity with no significant blooming artifact on gradient echo imaging. When imaged with gadolinium, they demonstrated only mild contrast enhancement. MRI is a valuable tool when investigating athletes with soft-tissue lesions over the lower limbs where the possibility of malignancy must be addressed. In selected cases, MRI may be sufficient to permit a conservative approach to the management of these patients.

Giant cell tumor of the tendon sheath originating from the ankle capsule: A case report and literature review

Giant cell tumor of the tendon sheath (GCTTS), also termed tendosynovial giant cell tumor, is a benign, slow-growing tumor that originates from the tendon sheath or bursa. GCTTS of the foot and ankle is much less frequently reported compared with GCTTS of the hand and knee. However, GCTTS should be considered as a differential diagnosis of soft tissue tumors of the foot and ankle. The optimal treatment strategy for GCTTS in the foot and ankle is controversial due to a scarcity of cases. The present study reports the case of a patient that presented with localized intra-articular GCTTS originating from the capsule of the ankle, which is a rare anatomical location for this tumor. Considering the proximity of the tumor to the adjacent non-tumorous structures, a less radical but complete resection of the tumor was performed, followed by a hydrogen peroxide lavage. There was no evidence of recurrence during a follow-up period of 12 months, and adjuvant radiotherapy was not administered to the patient. A pre-operative diagnosis for GCTTS in the foot and ankle is mainly based on the findings of clinical examination and magnetic resonance imaging, which also facilitates the determination of a surgical strategy. For a localized tumor, an integral resection, as opposed to a radical resection, with a hydrogen peroxide lavage may result in a favorable prognosis. However, the optimal treatment for diffuse GCTTS remains to be identified.

Multiple nodules on the sole of the foot

Ledderhose disease, or plantar fibromatosis, is a benign hyperproliferative disorder of the plantar aponeurosis. It presents as one or more round, firm slow-growing plaques or nodules on the plantar surface of the foot, typically on the medial side. The etiology is unknown, though it has been associated with trauma, liver disease, diabetes mellitus, epilepsy and alcoholism. Histopathological examination of plantar fibromatosis reveals dense fibrocellular tissue with parallel and nodular arrays of fibrocytes and fibrillar collagen with a distinctive cork-screw morphology. The differential diagnosis includes various fibroblastic and myofibroblastic proliferations.

Ultrasound versus magnetic resonance imaging for Morton neuroma: systematic review and meta-analysis

OBJECTIVES

To compare ultrasound (US) and magnetic resonance imaging (MRI) in the diagnosis of Morton's neuroma.

METHODS

Studies that assessed the diagnostic accuracy of US and MRI for Morton's neuroma were retrieved from major medical libraries independently by two reviewers up to 1 April 2014. Predefined inclusion and exclusion criteria were adopted.

RESULTS

277 studies were initially found, and the meta-analysis was conducted on 14 studies. US sensitivity was studied in five studies, MRI sensitivity in three studies, and bothin six studies. All studies used surgery as the reference standard. A high sensitivity (SE) of diagnostic testing was observed for both US (SE (95 % CI) = 0.91 (0.83-0.96)) and MRI (SE (95 % CI) = 0.90 (0.82-0.96)) with no significant differences between the two modalities in diagnosis (Q test p = 0.88). For MRI, specificity of test was 1.00 with a pooled estimation of 1.00 (0.73-1.00), while the pooled specificity was 0.854 (95 % CI: 0.41-1.00) for US. No differences were observed between US and MRI in study design (p = 0.76).

CONCLUSION

This meta-analysis shows that the SE of US (0.91) is equal to (p = 0.88) that of MRI (0.90) for identification of Morton's neuroma.

KEY POINTS

• For Morton's neuroma, US sensitivity is equal to MRI. • US is as accurate as MRI in diagnosing Morton's neuroma. • US may be the most cost-effective imaging method for Morton's neuroma.

Practical US of the forefoot

Disorders affecting the forefoot are common in the clinical practice. Accurate history and physical examination are the mainstays of diagnosis but imaging modalities are frequently obtained to confirm the clinical suspicion and plan appropriate treatment. In this article we will present the ultrasound (US) technique of examination of the forefoot followed by a brief description of the normal US anatomy and of US appearance of the most frequent forefoot disorders; rheumatoid arthritis, osteoarthritis, overuse arthropathy, Morton neuromas, bursitis, mucoid cysts, foreign bodies, bone disorders.

Reconstruction of bilateral tendoachilles with fascia lata graft

A 19 year old male presented with progressive enlargement of both tendoachilles for 2 years and difficulty in walking for 3 months. The neurological history and examination revealed progressive mental deterioration and ataxia. The blood investigation revealed hypercholesterolemia. We report this rare case of cerebrotendinous xanthomatosis with bilateral tendoachilles enlargement, which was treated by excision of bilateral tendoachilles and reconstruction with fascia lata. The American Orthopedic Foot and Ankle Society hindfoot score was 93/100 bilaterally and the subjective evaluation of the patient showed very good results.

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.

[Tumors of the foot: diagnostics and therapy]

Despite the compact anatomy with thin soft tissue coverage, diagnosis of both benign and malignant tumors of the foot is often delayed. Diagnostic errors are more common than in other body regions, as neoplasias are rarely considered. Barring a few exceptions the foot is not a typical predilection site for malignant musculoskeletal tumors, although, basically any tumor entity of the musculoskeletal system can affect the foot. Delays in specific diagnostic and therapeutic procedures of these lesions can entail serious consequences for patients as tumor size is a major prognostic factor for recurrence-free survival. In cases of an indistinct persistent swelling or bone lesion a tumorous process should always be considered to ensure early diagnosis and therapy of foot tumors.

Pigmented villonodular synovitis of the ankle: radiologic characteristics

BACKGROUND

Pigmented villonodular synovitis (PVNS) of the ankle is a rare benign proliferative growth of the synovium. Studies of the radiologic characteristics of ankle PVNS are sparse.

METHODS

To characterize the radiologic features of ankle PVNS, five patients with histologically proven ankle PVNS were retrospectively studied. The features of their radiographs, computed tomographic scans, and magnetic resonance images were reviewed, with emphasis on the morphological features, extension, margin, bone involvement, signal intensity, and degree of magnetic resonance enhancement.

RESULTS

All five lesions were diffuse, affecting the ankle and distal tibiofibular joint; three lesions also involved the subtalar joint. Radiography demonstrated extrinsic bone erosions with marginal sclerosis of the involved joints in all of the patients, but computed tomography identified this much better than did radiography. Magnetic resonance imaging revealed multiple lobulated soft-tissue masses in all of the cases. These soft-tissue masses surrounded the flexor hallux longus tendon and were hypointense on T1-weighted images, with a heterogeneous signal in two cases and homogenous hypointensity in three cases on fat-suppressed T2-weighted images. In one patient who underwent gadolinium-enhanced imaging, the masses showed intense enhancement.

CONCLUSIONS

Magnetic resonance imaging is the best way to reveal ankle PVNS. Magnetic resonance imaging findings of predominant hypointensity on all pulse sequences and standard radiography findings of bone erosion with marginal sclerosis are characteristic.

Giant cell tumor of a tendon sheath mimicking an axillary lymph node

A giant cell tumor of the tendon sheath (GCTTS) is 1 of the most common soft-tissue tumors of the hand and wrist, while the 2nd most frequent site is the ankle-foot complex. Although various solid tumors can develop in the axilla, GCTTS has not yet been reported. We describe the sonographic appearance of GCTTS in the axilla.