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

Investigations on ultrasonography in the diagnosis of nodular localized cutaneous neurofibroma

OBJECTIVE

To describe the ultrasound characteristics of nodular localized cutaneous neurofibroma (NLCN).

MATERIALS AND METHODS

Clinical features and ultrasound characteristics of 43 lesions of 40 patients pathologically proven as NLCNs at Peking University Shenzhen Hospital from October 2014 to May 2022 were analyzed retrospectively. The location, length-to-thickness (L/T) ratio, thickness-to-width (T/W) ratio, shape, margin, capsule, echogenicity, echotexture, posterior features, vascularity, and "rat tail sign" were evaluated.

RESULTS

All ultrasound findings showed almost perfect agreement. More than a half of NLCNs (n = 24, 55.8%, p < 0.001) were located in the subcutaneous fat layer wholly with well-demarcation from dermis and deep fascia. Most of the NLCNs were fusiform shape (n = 27, 62.8%, p < 0.001) in the long axis and oval shape (n = 35, 81.4%, p < 0.001) in the short axis. The other ultrasound findings of NLCNs included well-defined (n = 42, 97.7%, p < 0.001), encapsulated (n = 39, 90.7%, p < 0.001), predominately hypoechoic (n = 34, 79.1%, p < 0.001), homogeneous (n = 39, 90.7%, p < 0.001), posterior enhancement (n = 29, 67.4%, p = 0.033), and avascularity (n = 37, 86.0%, p < 0.001). Only a quarter (n = 11, 25.6%, p = 0.002) of lesions were recognized with the "rat tail sign."

CONCLUSION

NLCNs present as fusiform shape in long axis and round shape in short axis. The common ultrasound findings of NLCNs are well-defined, encapsulated, predominately hypoechoic, homogeneous lesion with posterior enhancement, and poor blood supply. The "rat tail sign" has low sensitivity in NLCNs.

Nodular fasciitis of the external auditory canal: Clinical case report and review of the literature

Nodular fasciitis is a benign reactive soft tissue tumor arising from fibroblasts and myofibroblasts. Its incidence is low and misdiagnosis is frequent especially for malignant lesions. This can lead to inappropriate and unnecessary invasive treatment. Nodular fasciitis of the external auditory canal is extremely rare. So far, around fifteen cases have been reported. We present here the case of a 90-year-old patient with nodular fasciitis of the right external auditory canal. The lesion extends anteriorly for 6.5 cm and reaches the posterior wall of the maxillary sinus. To our knowledge, this is the first case in the literature of an external auditory canal nodular fasciitis presenting as an inflammatory ear polyp with such a wide extension.

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.

Fasciitis ossificans: imaging features, histology, and differential diagnosis

AIM

To describe the imaging features of fasciitis ossificans and its histopathological features.

MATERIALS AND METHODS

Using a word search of existing pathology reports at the Mayo Clinic, six cases of fasciitis ossificans were identified. The clinical history, histology, and available imaging of the affected area were reviewed.

RESULTS

Imaging consisted of radiographs, mammograms, ultrasound images, bone scintigraphs, computed tomography (CT), and magnetic resonance imaging (MRI) images. All cases demonstrated a soft-tissue mass. The characteristic MRI appearance was a T2 hyperintense enhancing mass with surrounding soft-tissue oedema. Peripheral calcifications were seen on radiographs, CT, and/or ultrasound. Histological sections showed distinct zonation, with nodular fasciitis-like zones of myofibroblastic proliferation, which merged with osteoblasts that rim the ill-defined trabeculae of woven bone and became continuous with the mature lamellar bone surrounded by a thin layer of compressed fibrous tissue.

CONCLUSION

Imaging features of fasciitis ossificans are that of an enhancing soft-tissue mass located within a fascial plane with prominent surrounding oedema and mature peripheral calcification. Imaging and histology are that of myositis ossificans but occurring within the fascia. It is important that radiologists are aware of the diagnosis of fasciitis ossificans and appreciate its similarity to myositis ossificans. This is particularly important in anatomical locations with fascias but no muscle. Given the radiographic and histological overlap between these entities, nomenclature that encompasses both could be considered in the future.

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.

Nodular Fasciitis in the Preauricular Area in Pediatric Patients

Nodular fasciitis is a benign myofibroblastic and fibroblastic proliferative lesion that can be found in the subcutaneous tissue, muscle, and fascia. It is frequently observed in young adults aged 20 to 40 years and less commonly in pediatric patients. Rapid growth, high cellularity, and remarkable mitotic activity of this lesion could lead to misdiagnosis as a soft tissue sarcoma. Here, two cases of nodular fasciitis in the preauricular area in pediatric patients were reported. Nodular fasciitis in the preauricular area in a pediatric patient is rare. It could be confused with soft tissue sarcoma. However, nodular fasciitis should be suspected in a pediatric patient with a rapidly growing mass in the head and neck region. Surgical excision should be performed to confirm the histopathologic diagnosis when clinical diagnosis is uncertain and there is possibility of malignancy.

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.

Congenital nodular fasciitis: an extremely rare entity with review of literature

Background

Nodular fasciits is thought to be a benign superficial nodular disease, which most often occurs in the medium age of adolescence, mainly in the subcutaneous or fascial plane on the upper extremities and trunk. The percentage of this entity in children compared to adults is less than 10%. Most cases in childhood were reported at the head and neck region, therefore often renamed to cranial or extracranial fasciitis. These lesions often consists of sarcoma like structures. Preoperative imaging is often unspecific and the standard of treatment in children is biopsy or in some cases complete resection with narrow margin depending on size or location of the lesion.

Case presentation

We present a clinical case of a female newborn with a congenital nodular presternal mass. Biopsy revealed nodular fasciits by testing on USP6 gen rearrangement. With ongoing growth of her nodular thoracic tumor, she underwent complete resection with primary closure. We followed her clinical course over more than 3 years and give a review of the literature.

Conclusion

Only a minority of reports are documented with a neonate onset and none with a real congenital. We hereby presented the first case in literature of a proven congenital fasciits other than cranial/extracranial in a newborn and her clinical course.

NTRK-rearranged spindle cell neoplasm of the lower extremity: radiologic-pathologic correlation

Neurotrophic tyrosine receptor kinase (NTRK)-rearranged spindle cell neoplasm is a recently characterized soft tissue tumor and has been classified as provisional by the World Health Organization. Detection of the genetic rearrangement is important because these tumors are amenable to targeted tyrosine kinase inhibitor therapy, which can play a key role in patients with unresectable or advanced disease. Although the spectrum of histopathology associated with this entity is broad, one notable feature is the infiltrative growth pattern, which is most reminiscent of lipofibromatosis-like neural tumor. Description of their diverse histologic attributes has aided recognition, but so far little attention has been paid to correlating the gross appearance and imaging features of these lesions. In this report, we describe the clinical, imaging, histopathological, and genetic features of a soft tissue NTRK-rearranged spindle cell neoplasm. Inclusion of this more recently identified entity into the imaging differential of tumors with intratumoral relatively hypovascular nodules and infiltrative margins is important because testing for NTRK rearrangement is not routinely performed.