FDG-PET/CT imaging of elastofibroma dorsi

Superior scapular location: An overlooked albeit frequent finding in elastofibroma dorsi

PURPOSE

To explore the frequency of superior scapular elastofibroma dorsi in a large patient series with elastofibroma dorsi.

METHODS

136 chest CTs from January 2016 to July 2022 reporting elastofibroma dorsi were retrospectively analyzed. Three radiologists assessed the number, size, and location of elastofibroma dorsi. Continuous variables underwent two-tailed t-tests with p < 0.05. Inter-observer agreement was assessed by using Cohen's Kappa values.

RESULTS

In 136 patients (mean age, 75.9 +/- 9.8 years; 117 female), 330 elastofibroma dorsi were found. Six (4.4 %) patients had single, 87 (64 %) double, 22 (16.2 %) triple and 21 (15.4 %) quadruple lesions. All single and double lesions were in the inferior scapular regions. 43 (31.6 %) patients had superior scapular lesions in addition to inferior scapular elastofibroma dorsi. Inferior scapular elastofibroma dorsi was significantly larger than superior scapular elastofibroma dorsi. The probability of a right superior lesion was significantly higher in patients with a larger right inferior lesion. Inter-observer agreement was very good for experienced radiologist (κ = 94.1) and good for other radiologists (κ = 79.4 and κ = 78).

CONCLUSION

In contrast to current belief, superior scapular elastofibroma dorsi accompanying the typical inferior scapular lesions is not uncommon and can even manifest bilaterally. To the best of our knowledge, this is the first case series reporting prevalence of quadruple elastofibroma dorsi.

Molecular Imaging in Soft-tissue Sarcoma: Evolving Role of FDG PET

Soft tissue sarcomas are a rare and heterogenous group of tumors that account for 2% of all cancer-related deaths. Molecular imaging with FDG PET can offer valuable metabolic information to help inform clinical management of soft tissue sarcomas that is unique and complementary to conventional diagnostic imaging techniques. FDG PET imaging often correlates with tumor grade, can help guide biopsy, and frequently detects additional sites of disease compared to conventional imaging in patients being considered for definitive or salvage therapy. Traditional size-based evaluation of treatment response is often inadequate in soft tissue sarcoma and changes in metabolic activity can add significant value to interim and end of treatment imaging for high-grade sarcomas. FDG PET can be used for detection of recurrence or malignant transformation and thus play a vital role in surveillance. This article reviews the evolving role of FDG PET in initial diagnosis, staging, treatment response assessment, and restaging. Further studies on the use of FDG PET in soft sarcoma are needed, particularly for rare histopathologic subtypes.

PET-CT in Clinical Adult Oncology: II. Primary Thoracic and Breast Malignancies

Simple Summary

Positron emission tomography (PET), typically combined with computed tomography (CT), has become a critical advanced imaging technique in oncology. With PET-CT, a radioactive molecule (radiotracer) is injected in the bloodstream and localizes to sites of tumor because of specific cellular features of the tumor that accumulate the targeting radiotracer. The CT scan, performed at the same time, provides information to facilitate assessment of the amount of radioactivity from deep or dense structures, and to provide detailed anatomic information. PET-CT has a variety of applications in oncology, including staging, therapeutic response assessment, restaging, and surveillance. This series of six review articles provides an overview of the value, applications, and imaging and interpretive strategies of PET-CT in the more common adult malignancies. The second article in this series addresses the use of PET-CT in breast cancer and other primary thoracic malignancies.

Abstract

Positron emission tomography combined with x-ray computed tomography (PET-CT) is an advanced imaging modality with oncologic applications that include staging, therapy assessment, restaging, and surveillance. This six-part series of review articles provides practical information to providers and imaging professionals regarding the best use of PET-CT for the more common adult malignancies. The second article of this series addresses primary thoracic malignancy and breast cancer. For primary thoracic malignancy, the focus will be on lung cancer, malignant pleural mesothelioma, thymoma, and thymic carcinoma, with an emphasis on the use of FDG PET-CT. For breast cancer, the various histologic subtypes will be addressed, and will include ¹⁸F fluorodeoxyglucose (FDG), recently Food and Drug Administration (FDA)-approved ¹⁸F-fluoroestradiol (FES), and ¹⁸F sodium fluoride (NaF). The pitfalls and nuances of PET-CT in breast and primary thoracic malignancies and the imaging features that distinguish between subcategories of these tumors are addressed. This review will serve as a resource for the appropriate roles and limitations of PET-CT in the clinical management of patients with breast and primary thoracic malignancies for healthcare professionals caring for adult patients with these cancers. It also serves as a practical guide for imaging providers, including radiologists, nuclear medicine physicians, and their trainees.

Atlas of non-pathological solitary or asymmetrical skeletal muscle uptake in [18F]FDG-PET

Positron emission tomography (PET) using 2-deoxy-2-[¹⁸F]fluoro-d-glucose ([¹⁸F]FDG) is widely used in oncology and other fields. In [¹⁸F]FDG PET images, increased muscle uptake is observed owing exercise load or muscle tension, in addition to malignant tumors and inflammation. Moreover, we occasionally observe non-pathological solitary or unilateral skeletal muscle uptake, which is difficult to explain the strict reason. In most cases, we can interpret them as not having pathological significance. However, it is important to recognize such muscle uptake patterns to avoid misdiagnoses with pathological ones. Therefore, the teaching point of this pictorial essay is to comprehend the patterns of solitary or asymmetrical skeletal muscle uptake seen in routine [¹⁸F]FDG-PET scans. As an educational goal, you will be able to mention muscles where intense physiological [¹⁸F]FDG uptake can be observed, differentiate between physiological muscle uptake and lesion, and discuss with any physicians or specialists about uncertain muscle uptake.

Spectrum of Flurodeoxyglucose Positron Emission Tomography/Computerized Tomography Findings in Tumors and Tumor-Like Conditions of the Musculoskeletal System

Bone and soft-tissue tumors display a wide range of metabolic activity on flurodeoxyglucose positron emission tomography/computerized tomography (FDG PET/CT) imaging due to their varying histopathological features. Several benign tumors show high FDG uptake similar to that seen in malignant lesions and their metabolic characteristics can overlap. Certain benign tumors can potentially undergo malignant transformation and FDG PET/CT can play an important role in detecting malignant change. The intensity of metabolic activity on FDG PET/CT correlates with histological grade of malignant tumors and also acts as a valuable prognostic factor. FDG PET/CT plays an important role in the staging work up of bone and soft-tissue malignancies. It has been found to be superior to conventional imaging techniques primarily for detecting distant metastatic disease. Because of its ability to detect metabolic changes, FDG PET/CT is a very useful in assessing response to treatment. Metabolic response seen on FDG PET is a powerful surrogate marker of histopathological response to chemotherapy. The purpose of this article is to study the variable patterns of FDG uptake in tumors of the musculoskeletal system, describe the clinical utility of FDG PET/CT in predicting malignant change in benign tumors and discuss its role in staging, response assessment, and prognostication of malignant lesions.

PET/CT variants and pitfalls in bone and soft tissue sarcoma

Sarcomas are rare tumors of mesenchymal origin and comprise only around 1% of adult cancers. The abundance of sarcoma histiotypes, with distinct imaging characteristics, biology, clinical behavior and treatment strategy, result in a complex disease presentation, requiring management by multidisciplinary specialized sarcoma centers. Oncologic and musculoskeletal radiology guidelines provide minimal guidance and only fragmentary information on the indications of ¹⁸F-FDG PET/CT in sarcoma. Therefore, knowledge of various phenotypes with preference for bone and lymph node metastases or higher incidence of local and distant recurrence is essential to select the appropriate diagnostic imaging tests and its interpretation. Benign and malignant soft tissue and bone tumors often share common radiographic and metabolic imaging characteristics. In addition, metastases of various histiotypes might exhibit a spectrum of atypical imaging appearances. Therefore, imaging specialists need to be aware of these variants and associated pitfalls of sarcoma imaging.

Incidental Detection of Elastofibroma Dorsi With 68Ga-FAPI-46 and 18F-FDG PET/CT in a Patient With Esophageal Cancer

ABSTRACT

A 71-year-old man underwent 18F-FDG and 68Ga-FAPI-46 PET/CT for initial staging prior to surgery of a squamous cell carcinoma of the lower esophagus under the prospective study NCT04147494. Both scans showed increased uptake in the mid and distal esophagus without evidence of metastatic disease. A soft tissue right infrascapular mass with mild 18F-FDG and moderate 68Ga-FAPI-46 uptake was incidentally found. The patient underwent robotic-assisted Ivor-Lewis esophagectomy and excision of the right infrascapular mass. Histopathology of the right chest wall mass confirmed the diagnosis of elastofibroma.

Concomitant bilateral elastofibroma in the infrascapular and gluteal regions: a report of a rare case

BACKGROUND

Elastofibroma is a benign soft tissue tumor characterized by the presence of elastic fibers in a stroma of collagen and mature adipose tissue. It is reported to have a prevalence of 2.73%, as shown by a study through computed tomography (CT) images. However, multiple elastofibromas are uncommon.

CASE PRESENTATION

We report a case of concomitant bilateral elastofibroma in the infrascapular and gluteal regions. A 63-year-old male patient presented with a 6-month history of gradually increasing painless swellings in the upper back. On physical examination, firm, painless bilateral infrascapular masses were identified; these masses were more noticeable on forward arm flexion. Contrast-enhanced computed tomography showed well-defined bilateral infrascapular masses deep to the serratus anterior muscles as well as poorly defined bilateral gluteal masses with attenuation similar to that of the adjacent skeletal muscle. Magnetic resonance imaging revealed heterogenous masses with internal fatty streaks, consistent with elastofibroma. The histopathological diagnosis of elastofibroma was established based on the results of image-guided core-needle biopsy. The patient underwent surgical excision of both infrascapular elastofibromas with no post-operative complications. As the gluteal masses were incidental, surgical management was not warranted.

CONCLUSION

The presence of multiple elastofibromas is unusual. This report describes a rare case of multiple elastofibromas and its typical imaging features, and alerts us that elastofibromas are not exclusive to the periscapular region.

Elastofibroma Dorsi: Findings on 18F-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography

Elastofibroma dorsi (EFD) is a relatively rare soft-tissue pseudotumor that arises from mesenchymal tissue. We present a case of 48-year-old woman who underwent ¹⁸F fluorodeoxyglucose (FDG) positron emission tomography-computed tomography for initial staging of suspected carcinoma of the left breast. Incidental detection of soft-tissue masses showing moderate FDG uptake was seen in the bilateral infrascapular location characteristic of EFD.

Musculoskeletal Pitfalls on Fluorodeoxyglucose F 18 PET-Computed Tomography: Pictorial Review

A wide range of musculoskeletal processes can demonstrate increased uptake on PET-computed tomography (CT) with fluorodeoxyglucose (FDG) F 18, including reactive, benign neoplastic, inflammatory, traumatic, posttreatment, and arthritic conditions that may mimic malignancy. In addition, physiologic causes of increased FDG uptake such as asymmetric muscle use and presence of brown fat can lead to increased FDG uptake and potential false-positive results. This article presents various case examples of non-malignant musculoskeletal hypermetabolism on 18F-FDG PET-CT and describes useful tools to avoid the potential pitfall of misinterpreting these as malignancy.

MRI findings and demographics of elastofibroma dorsi: assessment of diffusion-weighted imaging and contrast enhancement patterns

Background Elastofibroma dorsi is a rare pseudotumoral lesion. Thus, there is no report of magnetic resonance imaging (MRI) findings that investigates multiple patients particularly with respect to diffusion-weighted imaging (DWI) findings and contrast enhancement patterns. Purpose To describe the imaging findings of elastofibroma on MRI, particularly DWI findings and contrast enhancement patterns, and to further investigate patient demographics. Material and Methods Forty-four patients with elastofibroma that underwent MRI were enrolled in this retrospective study. All images were evaluated by two radiologists to visually assess the signal intensity for each sequence. Enhanced elastofibromas were classified into four categories to assess the enhancement pattern. Differences in gender and laterality were also assessed statistically. Results An equal number of men and women were included (n = 22 each). There was no significant difference in laterality ( P = 0.783). All lesions (73 lesions) had low signal intensity on both T1-weighted (T1W) and T2-weighted (T2W) images: heterogeneous in 56, homogeneous in 17. None of the 41 lesions with DWI had true abnormal diffusion restriction. The average ADC value was 1.36 × 10^-3 ± 0.29 mm²/s. All 31 lesions that had contrast-enhanced MRI were classified according to enhancement pattern: homogeneous (three lesions, 9.7%); heterogeneous (15 lesions, 48.4%); streak-like (three lesions, 9.7%); and rim-like (ten lesions, 32.2%). Conclusion There were no statistically significant differences in gender or laterality. Elastofibroma showed homogeneous to heterogeneous low signal intensity on T1W and T2W images. No lesion showed abnormal diffusion restriction, and all lesions demonstrated enhancement on MRI.

Elastofibroma dorsi

We present a 60-year-old man with biopsy-proven metastatic squamous cell carcinoma of the right inguinal and external iliac lymph nodes with unknown primary. Hypermetabolic soft tissue masses were identified in bilateral subscapular regions on follow-up positron emission tomography (PET)-computed tomography (CT) after completion of chemoradiation. The right subscapular mass was biopsied under CT guidance, and histopathology showed it to be elastofibroma dorsi. Elastofibroma dorsi is a benign tumor with no malignant potential; due to its ill-defined appearance and tracer uptake on PET-CT, it can be misdiagnosed as soft tissue sarcoma. This report describes the typical location and imaging features of this incidental hypermetabolic mass.

Incidental detection of elastofibroma dorsi on PET-CT: initial findings and changes in tumor size and standardized uptake value on serial scans

OBJECTIVE

We describe changes in elastofibroma dorsi (EFD) as observed in serial fluorine-18 fluorodeoxyglucose (F-FDG) PET-computed tomography (CT) imaging studies.

MATERIALS AND METHODS

F-FDG PET-CT studies carried out between January 2006 and January 2015 at a single institution were reviewed by an experienced radiologist and nuclear medicine specialist. When available, previous or subsequent imaging studies were reviewed to evaluate changes in EFD.

RESULTS

Of 28 500 PET-CT studies carried out, EFD was identified in 68 from 20 patients (mean age 67.1±10.2 years; 14 women). Five patients had unilateral lesions and 15 patients had bilateral lesions. Eighteen patients had oncologic diseases. The mean size of EFD at first presentation was 13.95±5.90 mm and the mean homogeneous low-grade F-FDG uptake was maximum standardized uptake value (SUVmax) 2.24±0.95. One or more additional CT scans were performed in 17 patients; the mean interval between the first and last scans was 57.4±39.2 months. EFD was unchanged in size in 7/17 (41%) and showed slow growth in 10/17, reaching a mean size of 19 mm. The mean monthly growth rate was 0.1±0.10 mm. PET imaging in 11 patients showed a mean first SUVmax of 2.08±1.17 and a mean last SUVmax of 2.74±1.05 after a mean of 47.5±31.5 months (P=0.63).

CONCLUSION

Serial PET-CT studies may show a stable or slowly enlarging mass on a CT scan without changes in F-FDG uptake on PET imaging. Familiarity with CT appearances and F-FDG uptake of EFD are important for correct interpretation of F-FDG PET-CT studies.

Unusual Presentation of Elastofibroma Dorsi on 18F-FDG-PET/CT: A Case Report

A 70-year-old male patient underwent an Fluorodeoxyglucose-positron emission tomography-computed tomography for staging of a left parahilar lung neoplasm found during work-up for fatigue and asthenia. The scan demonstrated a hypermetabolic lung tumor, a hypermetabolic pleural effusion and 4 hypermetabolic bilateral soft tissue lesions of the chest wall corresponding to 4 elastofibroma dorsi. Initially, the oncologic disease was classified as stage IV because of the hypermetabolic pleural effusion. A transbronchial biopsy showed squamous cell carcinoma and the cytology of the pleural effusion revealed no malignant cells. As the other 4 hypermetabolic thoracic wall lesions were correctly diagnosed as benign despite their unusual presentation, the patient underwent surgery by left pneumonectomy and mediastinal lymphadenectomy. The lymph node involvement required adjuvant chemotherapy. Diagnostic confidence of the benignity of the hypermetabolic chest wall lesions allowed a more aggressive treatment with a better outcome after a malignant pleural effusion was excluded.

Elastofibroma: clinical results after resection of a rare tumor entity

Elastofibroma (EF) is a benign proliferation of connective tissue and is typically located at the dorsal thoracic wall. Most patients complain about pain during motion in the shoulder girdle. The aim of our study was to evaluate the outcome after surgical treatment of EF. This study provides an overview of typical clinical findings, diagnostics and pathogenesis of this rare entity. In this retrospective study we analyzed data of 12 patients (6 male, 6 female) with EF treated in our institution between 2004 and 2012. The mean follow-up was 4.7 years (range: 5 months to 7.5 years). All tumors were found to be unilateral and all patients had a negative medical history for EF. Visual analogue scale and range of motion (ROM) was documented pre- and postoperatively. In all patients indication for surgical resection was pain or uneasiness during movement. There was no statistically significant difference in ROM of the shoulder between pre- and postoperatively but all patients reported significantly less pain after surgical resection. Patients benefited from tumor resection by a significant reduction of pain levels and improvement of the motion-dependent discomfort.

Musculoskeletal tumors and tumor-like conditions: common and avoidable pitfalls at imaging in patients with known or suspected cancer: Part A: benign conditions that may mimic malignancy

A wide range of musculoskeletal tumors and tumor-like conditions may be encountered when patients undergo radiological examinations. The imaging features of certain normal, reactive, benign neoplastic, inflammatory, traumatic, and degenerative processes in the musculoskeletal system may mimic malignant tumor; misinterpretation of the imaging findings can lead to inappropriate clinical management of the patient. This review describes and illustrates a number of such mimics that we have commonly encountered in our oncological imaging practice, and provides suggestions for avoiding each of these pitfalls. Because many orthopaedic surgeons interpret radiological images themselves, they need to be as aware as radiologists about these issues.

Painful elastofibroma dorsi: a report of a case and a brief review of the literature

Elastofibroma dorsi (ED) is an uncommon, slow-growing, benign, soft tissue tumor of unclear pathogenesis, typically located at the subscapular region of elderly people. It may be unilateral or bilateral. Though many patients are asymptomatic, ED can cause local deformity and symptoms such as periscapular pain or discomfort. Herein we report a case of a 65-year-old woman with painful ED. Clinical features, radiodiagnostic, intraoperative, and pathologic findings, and a brief review of the literature are performed.

[Positron emission tomography-computed tomography in tumors of the locomotor apparatus]

Positron emission tomography/computed tomography (PET/CT) is a hybrid imaging technique that combines the anatomic information from CT with the metabolic information acquired from PET after the administration of specific radiotracers, the most commonly used of which is F18-fluorodeoxyglucose (FDG). In oncology, this technique is based on the increased uptake of FDG by malignant lesions. In the locomotor apparatus, some uptake by bones and soft tissues is physiological or benign and this uptake must be differentiated from uptake by malignancies, whether primary or secondary. The most important limitations are active inflammatory or infectious processes, which are positive on PET images, and malignant lesions that are smaller than 1cm, cystic, necrotic, or low-grade, which are negative on PET images. PET/CT in the locomotor apparatus is especially useful for the detection of metastases from the most common tumors. It is also used for staging and monitoring the response to treatment of some hematological tumors like lymphoma, where it is fundamental to determine whether the bone marrow has been infiltrated, or myeloma. Lastly, although it is not yet an established indication, PET/CT is being increasingly used to study sarcomas, because it can provide additional information that can be useful for the characterization and grading of tumors, for guiding biopsies, for staging and re-staging, and for evaluating the response to neoadjuvant therapy as well as for evaluating new drugs in clinical trials.

Review of Physiologic and Pathophysiologic Sources of Fluorodeoxyglucose Uptake in the Chest Wall on PET

The chest wall can be defined as the osseous and soft tissue structures that form the outer framework of the thorax and move during breathing. Topics discussed in this article include physiologic uptake of fluorodeoxyglucose, benign diseases of the chest wall, and malignant tumors of the chest wall.