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

Review of Soft Tissue Masses of the Foot and Ankle: Magnetic Resonance Imaging Features

A large number of soft tissue masses affect the foot and ankle, with the majority being benign. Benign and malignant soft tissue lesions usually present as lumps, and it is important to differentiate between them to allow for optimal management. Imaging, in particular magnetic resonance imaging (MRI), can contribute to narrow the differential diagnosis of soft tissue masses of the foot and ankle by describing its exact location, internal signal characteristics, presence of enhancement, and its relation to adjacent structures. In this review, we review the literature to describe the most common soft tissue masses around the foot and ankle, focusing on the MRI features of the lesions.

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.

Unusual multiloculated serpiginous ganglion of the foot

Ganglions are cystic lesion more commonly seen around the wrist joint. Gangliomas of plantar aspect of the foot are rare. We have presented a case of an unusual serpiginous ganglioma of the plantar aspect of the foot. Less literature is available regarding plantar foot gangliomas. The treatment is challenging because of occurrence of the lesion at weight bearing zone. Available options for treatment includes conservative with splint, intralesional injection,arthroscopic excision and open excision.

[Sonography of the foot in rheumatology : Ultrasound diagnostics of the ankle joint and foot in the rheumatological routine]

Ultrasound examination of the joints is an essential component of diagnostics in rheumatology. Due to its easy accessibility, excellent image definition of soft tissue and bone surfaces with standardized scan sections and scoring systems, ultrasound examination of the joints enables decisions to be made on early and differential diagnostics, treatment monitoring and prognosis. Involvement of the ankle and foot is a common problem in both inflammatory and degenerative rheumatological diseases. Persisting inflammatory processes and bone destruction increase the burden of disease by causing a loss of mobility due to pain. As treatment is often prolonged it is an important issue for both the quality of life of affected patients and a burden on the resources of the healthcare system. The anatomical characteristics of the foot make it difficult to draw diagnostic conclusions by physical examination only. These diagnostic gaps in the remaining rheumatological questions can often be answered by ultrasound examination of the joint.

A bump: what to do next? Ultrasound imaging of superficial soft-tissue palpable lesions

Soft-tissue palpable lesions are common in clinical practice, and ultrasound (US) represents the first imaging option in the evaluation of a patient with a soft-tissue swelling. A full and systematic US assessment is necessary, however. This includes grayscale, color- and power-Doppler, spectral-Doppler, and possibly elastography facilities, as well as a trained operator. Several lesions showing characteristic US features can be diagnosed confidently, without any further work-up, and the high spatial resolution of ultrasound in the superficial layers can be a powerful tool to discriminate their etiologies. Second-level options, to be reserved for indeterminate cases or those suspected malignant at initial ultrasound, include magnetic resonance imaging, percutaneous fine-needle aspiration or biopsy, and surgical-excision biopsy. In this article, we discuss the proper US approach for addressing superficial soft-tissue lesions.

[Foot and ankle tumours : Part I: overview of incidence, diagnosis and staging of pedal tumours]

CLINICAL ISSUE

Foot and ankle tumours are rare. Part I of this paper provides a survey about tumour distribution regarding age and location of benign and malignant bone and soft tissue tumours.

STANDARD RADIOLOGICAL METHODS

All diagnostic radiological procedures are used for the diagnostic work-up of pedal tumours, in particular plain radiography, MRI, and ultrasonography.

METHODICAL INNOVATIONS

Dual-energy CT proves to be a valuable (differential) diagnostic tool in identifying urate dihydrate crystals.

PERFORMANCE

There are no reliable numbers available on accuracy of the aforementioned diagnostic procedures regarding tumour detection and identification. This is particularly true for soft tissue tumours which are small and well-defined, thus requiring histological clarification.

ACHIEVEMENTS

To evaluate pedal tumours correctly and reasonably, a full range of radiological diagnostics should be employed. Neither plain radiography alone nor a stand-alone MRI examination-depending on the tumour site-are sufficient to characterize such tumours including staging.

PRACTICAL RECOMMENDATIONS

Plain radiography remains the first-choice imaging modality. Ultrasonography is superior to reliably detect and identify ganglion cysts. MRI, however, continues to remain the upmost diagnostic modality of choice for evaluating foot and ankle tumours. CT possesses unchallanged diagnostic power to assess osseous changes. Bone scintigraphy (including SPECT-CT) and FDG-PET imaging are used when multifocal distribution or metastatic disease are suspected or to detect avidity of the pedal lesions, respectively.

[Foot and ankle tumours : Part II: Malignant bone tumours and soft tissue tumours of the foot with differential diagnostic hints]

CLINICAL ISSUE

Both benign and malignant tumours are encountered in the foot and ankle. Due to their rarity, however, diagnosis is often uncertain. Usual criteria such as tumour size, invasiveness or pain fail to differentiate benign from malignant neoplasias.

STANDARD RADIOLOGICAL METHODS

Plain radiography and-due to the complex foot anatomy-CT are important in the diagnostic evaluation of primary bone tumours. In the case of soft tissue tumours, ultrasonography is used to identify ganglion cysts. Tumour evaluation and staging are then performed using MRI. Nuclear imaging comes into play when multifocal, metastatic or systemic spread of the disease is suspected or if a biopsy procedure is planned.

METHODICAL INNOVATIONS

For the role of dual-energy CT, please refer to part I. Whether dual-energy CT is suitable to assess bone marrow oedema patterns is still debated.

SPECIAL FEATURES OF FOOT AND ANKLE TUMOURS

Primary bone tumours generally present in the ankle or the hindfoot. Malignant bone tumours, e. g. chondrosarcoma, are primarily found in the latter. On the other hand, soft tissue tumours generally present in the mid- and forefoot regions.

ACHIEVEMENTS

While the radiologic diagnostic evaluation of pedal bone tumours is quite reliable, caution is urgently needed in the case of soft tissue tumours because there are many confusing differential diagnoses.

PRACTICAL RECOMMENDATIONS

Proper X‑ray examination of the foot (at least in two plains) or with special views according to bony pathology is needed. All soft tissue masses that are not cysts should be evaluated further. MRI remains the diagnostic modality of choice but never stands alone! Caution: Size and well-defined margins of pedal soft tissue tumours are not considered criteria regarding whether a tumour is malignant or not.

Ultrasound-guided intervention in the ankle and foot

In this comprehensive review, we discuss the main interventions performed in the foot and ankle for Achilles tendinopathy, Morton's neuromas and Plantar fasciitis as well as techniques for intra-articular and peritendinous injections. We present the different imaging techniques and injectable agents that can be used in clinical practice, trying to help the reader decide the most appropriate way of managing the patient with a problem in the ankle and foot.