Imaging findings of radiologically misdiagnosed nodular fasciitis

Development of clinical and magnetic resonance imaging-based radiomics nomograms for the differentiation of nodular fasciitis from soft tissue sarcoma

BACKGROUND

Accurate differentiation of nodular fasciitis (NF) from soft tissue sarcoma (STS) before surgery is essential for the subsequent diagnosis and treatment of patients.

PURPOSE

To develop and evaluate radiomics nomograms based on clinical factors and magnetic resonance imaging (MRI) for the preoperative differentiation of NF from STS.

MATERIAL AND METHODS

This retrospective study analyzed the MRI data of 27 patients with pathologically diagnosed NF and 58 patients with STS who were randomly divided into training (n = 62) and validation (n = 23) groups. Univariate and multivariate analyses were performed to identify the clinical factors and semantic features of MRI. Radiomics analysis was applied to fat-suppressed T1-weighted (T1W-FS) images, fat-suppressed T2-weighted (T2W-FS) images, and contrast-enhanced T1-weighted (CE-T1W) images. The radiomics nomograms incorporating the radiomics signatures, clinical factors, and semantic features of MRI were developed. ROC curves and AUCs were carried out to compare the performance of the clinical factors, radiomics signatures, and clinical radiomics nomograms.

RESULTS

Tumor location, size, heterogeneous signal intensity on T2W-FS imaging, heterogeneous signal intensity on CE-T1W imaging, margin definitions on CE-T1W imaging, and septa were independent predictors for differentiating NF from STS (P < 0.05). The performance of the radiomics signatures based on T2W-FS imaging (AUC = 0.961) and CE-T1W imaging (AUC = 0.938) was better than that based on T1W-FS imaging (AUC = 0.833). The radiomics nomograms had AUCs of 0.949, which demonstrated good clinical utility and calibration.

CONCLUSION

The non-invasive clinical radiomics nomograms exhibited good performance in the differentiation of NF from STS, and they have clinical application in the preoperative diagnosis of diseases.

Multimodality imaging features of USP6-associated neoplasms

Since the discovery of USP6 gene rearrangements in aneurysmal bone cysts nearly 20 years ago, we have come to recognize that there is a family of USP6-driven mesenchymal neoplasms with overlapping clinical, morphologic, and imaging features. This family of neoplasms now includes myositis ossificans, aneurysmal bone cyst, nodular fasciitis, fibroma of tendon sheath, fibro-osseous pseudotumor of digits, and their associated variants. While generally benign and in many cases self-limiting, these lesions may undergo rapid growth, and be confused with malignant bone and soft tissue lesions, both clinically and on imaging. The purpose of this article is to review the imaging characteristics of the spectrum of USP6-driven neoplasms, highlight key features that allow distinction from malignant bone or soft tissue lesions, and discuss the role of imaging and molecular analysis in diagnosis.

Role of Imaging in Initial Prognostication of Locally Advanced Soft Tissue Sarcomas

BACKGROUND

Although imaging is central in the initial staging of patients with soft tissue sarcomas (STS), it remains underused and few radiological features are currently used in practice for prognostication and to help guide the best therapeutic strategy. Yet, several prognostic qualitative and quantitative characteristics from magnetic resonance imaging (MRI) and positron emission tomography (PET) have been identified over these last decades.

OBJECTIVE

After an overview of the current validated prognostic features based on baseline imaging and their integration into prognostic tools, such as nomograms used by clinicians, the aim of this review is to summarize more complex and innovative MRI, PET, and radiomics features, and to highlight their role to predict indirectly (through histologic grade) or directly the patients' outcomes.

Nodular Fasciitis of the Nose and External Auditory Canal: Two Rare Case Reports

Nodular fasciitis(NF) is a proliferative disease of fibroblasts and myofibroblasts that generally affects subcutaneous tissue, muscle tissue, and fascia. NF usually occurs in young adults aged 20-40 and is more common in the upper extremities and relatively rare in the region of the head and neck. Here, we report on two patients with NF in the ear and nose. Under general anesthesia, the masses of NF were completely resected along the safety margin. The patients recovered well after surgery and there was no recurrence after more than half a year of follow-up.

Clinical characteristics of nodular fasciitis of the ear in children

The rate of early misdiagnosis in patients with nodular fasciitis of the ear is high. To provide a basis for clinical diagnosis and treatment, we aimed to summarise the clinical manifestations, imaging results, pathological findings, treatment strategies, and postoperative follow-up results for three cases of paediatric nodular fasciitis (two girls, one boy) treated in the Department of Otorhinolaryngology, Head and Neck Surgery, at Beijing Children's Hospital of Capital Medical University from 2018 to 2020. The average age at diagnosis was 24 months. Lesions occurred in the left ear in two cases and right ear in one case. All patients had a history of biopsy before surgery. Rapid growth was observed following biopsy in two patients, and anti-inflammatory treatment was ineffective in all three cases. Fluorescence in situ hybridisation analysis of ubiquitin-specific peptidase 6 (USP6) was performed in two of the three cases, with positive results. The lesions exhibited hypo-intensity or iso-intensity on T1-weighted magnetic resonance imaging (MRI) and heterogeneous hyper-intensity on T2-weighted MRI. "Fascial tail" signs were observed on imaging in all cases. Surgical resection was performed in all cases. Intact ear appearance was observed at follow-up, and there were no cases of recurrence.Conclusion: Combining clinical features with imaging findings may improve the accuracy of preoperative diagnosis in patients with nodular fasciitis. In addition to pathological findings, genetic testing for USP6 may aid in diagnosis. The final diagnosis should be based on comprehensive assessment. Complete surgical resection can prevent recurrence. What is Known: • Paediatric NF around the ear is rare and is easily misdiagnosed as other inflammatory masses that have a higher incidence in children. • Most previous reports of NF were case reports. What is New: • Combining clinical and imaging findings with genetic testing for USP6 rearrangement may improve the accuracy of preoperative diagnosis in patients with NF. Nonetheless, the final diagnosis should be based on comprehensive assessment. • The present paper is significant in that it represents the only report of three cases of ear NF in children with a complete medical history and prognosis.

Occipital nodular fasciitis easily misdiagnosed as neoplastic lesions: A rare case report

BACKGROUND

Nodular fasciitis (NF) is a benign disease originating from fascial tissue and most commonly occurs in the extremities, followed by the trunk, head, and neck. NF of the head and neck occurs mainly in the face and neck, and it has not been reported in the occipital region.

CASE SUMMARY

A 30-year-old man was admitted because of a mass in the left occipital region. Imaging examination revealed a soft tissue nodule in the left occipital area. An enhanced magnetic resonance imaging scan showed characteristic inverted target and fascial tail signs. Histopathological analysis showed a large amount of spindle cell proliferation, and immunohistochemistry showed positive expression of SMA in the spindle cells in the lesion. Finally, nodular fasciitis was diagnosed.

CONCLUSION

NF of the head and neck is rare, but the possibility of NF should be considered when nodules or masses with rapid subcutaneous growth are found and tenderness in the head and neck is present. Imaging examination, in combination with clinical manifestations and histopathological examination, can improve the diagnostic accuracy for the disease. After diagnosis, local surgical resection is the first choice of treatment.

MR imaging features and a redefinition of the classification system for nodular fasciitis

To analyze magnetic resonance imaging features of nodular fasciitis and redefine the system for classifying this class of lesions.Twenty-seven patients with nodular fasciitis and 71 patients with other soft tissue lesions who underwent surgery or biopsy were retrospectively analysed. Demographic information, medical history, and magnetic resonance imaging features were collected. Classification of nodular fasciitis was performed based on a redefined system. Comparison between 2 groups was performed with Chi-square or Fisher exact test.For nodular fasciitis, the longest average lesion diameter was 1.87 cm (range, 0.52-5.46 cm), and 40.7% of lesions were located in the upper extremities, while 29.6% were located in the head and neck. Compared with skeletal muscle, most lesions exhibited isointensity on T1-weighted imaging and hyperintensity on T2-weighted imaging, and 45.5% of the lesions exhibited rim enhancement, 40.9% showed obvious homogenous enhancement, while 13.6% showed no enhancement or slight enhancement. The subcutaneous type accounted for 25.9% of cases, the fascial type 25.9%, the intramuscular type 29.6%, and the unclassified type 18.5%. The "fascia tail sign" was more frequently observed in nodular fasciitis than in other soft tissue lesions (P < .001). Nodular fasciitis was slightly more likely to present with the "inverted target sign" and "solar halo sign" than other soft tissue lesions (P > .05). The "cloud sign" only appeared in nodular fasciitis (P < .05).The "fascia tail sign" and "cloud sign" could help differentiate nodular fasciitis from other soft tissue lesions. A new classification may improve understanding about nodular fasciitis.

Primary Site Identification of Soft-Tissue Mass: Things to Know in MRI Assessment

The spectrum of soft-tissue mass is varied, including neoplastic and nonneoplastic/inflammatory lesions. However, soft-tissue tumors have similar imaging findings and, therefore, the diagnosis of soft-tissue mass is challenging. Although careful assessment of the internal characteristics on imaging can often narrow the differential diagnoses, the differential diagnosis may be out of the question if identification of the soft-tissue mass origin is missed. The purpose of this article is to review the imaging findings and the essential anatomy to identify the primary site of the soft-tissue mass, and discuss the associated potential pitfalls. In order not to fall into a pitfall, recognition of characteristic imaging findings indicating the origin of the soft-tissue mass and anatomical knowledge of the normal tissue distribution are necessary. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY STAGE: 3.

Revisiting the WHO classification system of soft tissue tumours: emphasis on advanced magnetic resonance imaging sequences. Part 1

The World Health Organisation (WHO) classification categorises musculoskeletal soft tissue tumours (STT) based on their similarity to normal adult tissue. The most recent WHO classification provides an updated scheme that integrates biological behaviour as a distinguishing feature in each subcategory; STTs are further subdivided as benign, intermediate (locally aggressive or rarely metastasising), and malignant. Although malignant STTs are infrequent in routine orthopaedic radiology practice, musculoskeletal radiologists must be familiar with the imaging appearance of malignant STTs and distinguish them from their benign counterparts for appropriate management. Magnetic resonance imaging (MRI) is the ideal modality for the detection, characterisation, and local staging of STT. This review will discuss the most recent updates to the WHO classification of STT that are relevant to radiologists in a routine clinical practice with MRI correlation. The utility of advanced MRI sequences such as diffusion weighted imaging, dynamic contrast enhanced sequences, and magnetic resonance spectroscopy to provide insight into the biological behaviour of various STTs is highlighted.

A rapidly progressing mass of nasal cavity in a child: Nodular fasciitis

Nodular fasciitis (NF) is a benign, self-limiting, reactive soft tissue tumor that is composed of fibroblasts and myofibroblasts and is often misdiagnosed as a malignant lesion. Nodular fasciitis is often reported in adults but rarely seen in children. We report the case of a 3-year-old girl with a rapidly growing NF in the left nasal cavity. The initial biopsy suggested the possibility of a spindle cell tumor or low-grade malignant tumor, respectively. The child underwent complete excision of the tumor. With the help of immunohistochemistry and pathological consultation, the final diagnosis was confirmed as NF. There was no recurrence during an 18-month follow-up period.

Intraarticular Nodular Fasciitis of the Knee With MHY9-USP6 Fusion: A Case Report

Background. Nodular fasciitis (NF) is a self-limiting, benign mesenchymal neoplasm of fibroblastic/myofibroblastic origin. Due to the fast growth, cellularity, and frequently observed high mitotic count, it is commonly misdiagnosed as a sarcoma, often resulting in overtreatment. Intraarticular examples of NF are extremely rare. Radiologically, NF can mimic fibroma of the tendon sheath, tenosynovial giant cell tumor, and synovial chondromatosis. Histology can vary from hypercellular, mitotically active lesions to fibrotic, less cellular ones, and can, therefore, mimic other benign and low-grade malignant neoplasms. Recently, the MYH9-USP6 fusion has been found in up to 92% of NF. Case Presentation. In this article, we report a case of a 38-year-old patient with an intraarticular lesion, radiologically suspicious of tenosynovial giant cell tumor. Histology demonstrated a spindle cell lesion composed of fibroblasts/myofibroblasts embedded in a highly collagenous/hyalinized stroma, partly arranged in short fascicles. Extravasated erythrocytes and rare mitotic figures were present. Immunohistochemically, tumor cells expressed smooth muscle actin and were negative for desmin, β-catenin, CD34, and SOX10. These findings rendered the diagnosis of NF. Molecular analysis using next-generation sequencing (Archer FusionPlex Sarcoma Panel) revealed gene rearrangement involving USP6 and MYH9 supporting the diagnosis of NF in the knee joint. Conclusions. Radiological and histological features of NF can overlap with other benign and low-grade malignant lesion. Identification of the USP6 gene rearrangements or finding of the MYH9-USP6 fusion, especially in core needle biopsies and in the lesions occurring at unusual sites, can result in adequate therapeutic approach avoiding overtreatment.

Soft-Tissue Tumors of the Hand-Imaging Features

Imaging studies of the hands and fingers are common, and radiologists are generally comfortable with traumatic and degenerative conditions which arise frequently in daily practice. However, a variety of common and uncommon soft-tissue tumors also occur in the hand, the appropriate diagnosis of which can be a source of confusion for both clinicians and radiologists. These lesions often have overlapping imaging characteristics; however, a structured approach can help provide a focused differential diagnosis and impact further workup and management. We discuss several such tumors, categorizing them as cystic-appearing, noncystic masses along tendons and aponeuroses, adipocytic tumors, vascular lesions, and miscellaneous lesions with imaging features that can aid diagnosis.

A case of nodular fasciitis that was difficult to distinguish from sarcoma

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Nodular fasciitis is difficult to distinguish from sarcoma.

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Clinical and pathological findings may not correspond, as in our case.

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If sarcoma cannot be excluded, treatment should consider the risk of malignancy.

Introduction

Nodular fasciitis is a reactive proliferative lesion. It is often difficult to distinguish from sarcoma, such as malignant peripheral nerve sheath tumor (MPNST). Therefore, both pathological findings and clinical features must be considered.

Presentation of case

A 75-year-old man presented with a 1 × 1 cm mass on his left forearm that had enlarged rapidly without specific symptoms. Magnetic resonance imaging revealed a mass adjacent to brachioradialis. The lesion showed iso-intensity to muscle on T1-weighted images and hyperintensity on T2-weighted images. We made a clinical diagnosis of nodular fasciitis. Under observation, the mass gradually decreased in size and disappeared after two months. Four years later, another lesion appeared at the same site. We performed total excisional biopsy and histopathological examination indicated low grade MPNST or recurrent nodular fasciitis. Since malignancy could not be excluded, wide resection was performed. At 4 years postoperatively, there has been no recurrence.

Discussion

In this patient, nodular fasciitis of the right forearm was diagnosed clinically and showed spontaneous regression. However, recurrence was noted after four years. While the clinical features suggested recurrent nodular fasciitis, pathological findings indicated the possibility of low grade MPNST.

Conclusion

When it is difficult to determine whether a lesion such as nodular fasciitis is benign or malignant, the patient should be managed by considering the possibility of malignancy.