Role of FDG-PET/CT for monitoring soft tissue tumors

Large Multicentric Synchronous Extra-Abdominal Fibromatosis of the Leg and Foot: A Case Report

Extra-abdominal fibromatosis is an uncommon, benign locally aggressive fibrous soft-tissue tumor that usually occurs in the shoulders, chest wall, back, thigh, and head and neck affecting the young adult population. It is commonly located in the subcutaneous tissue and may infiltrate the adjacent skeletal muscles. We hereby report a rare case of a large extra-abdominal fibromatosis of the leg and foot in a 38-year-old woman. The patient presented with a large voluminous lesion clinically and on imaging, which was difficult to diagnose. Magnetic resonance imaging (MRI) was very helpful in diagnosing the lesion. It revealed a large relatively well-defined, lobulated hypointense mass in the posterior compartment of the leg with extension into the lower thigh and foot with local infiltration into the gastrocnemius and soleus muscles. An incisional biopsy was performed, and the mass was diagnosed on pathological examination as a spindle-shaped fibroblast proliferation suggesting extra-abdominal fibromatosis.

PET-CT in the Evaluation of Neoadjuvant/Adjuvant Treatment Response of Soft-tissue Sarcomas: A Comprehensive Review of the Literature

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In soft-tissue sarcomas (STSs), the use of positron emission tomography-computed tomography (PET-CT) through a standardized uptake value reduction rate correlates well with histopathological response to neoadjuvant treatment and survival.

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PET-CT has shown a better sensitivity to diagnose systemic involvement compared with magnetic resonance imaging and CT; therefore, it has an important role in detecting recurrent systemic disease. However, delaying the use of PET-CT scan, to differentiate tumor recurrence from benign fluorodeoxyglucose uptake changes after surgical treatment and radiotherapy, is essential.

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PET-CT limitations such as difficult differentiation between benign inflammatory and malignant processes, inefficient discrimination between benign soft-tissue tumors and STSs, and low sensitivity when evaluating small pulmonary metastases must be of special consideration.

Radiographic findings useful for diagnosis of primary chest wall lymphoma without preceding pleural disease: A case report

A 70‐year‐old man with no history of pleural diseases had a dumbbell‐shaped chest wall mass extending from the thoracic cavity to the spinal canal at the intervertebral foramen without bone destruction. Computed tomography revealed a positive a ‘pleural sandwich sign’, where the intercostal artery was enveloped by the mass. A high maximum standard uptake value was noted on fluorodeoxyglucose‐positron emission tomography. No lesions were found in areas other than the chest wall. CT‐guided biopsy was performed and he was diagnosed with primary chest wall lymphoma. This case report suggests that these radiographic findings may be helpful for diagnosing chest wall lymphomas even in patients without prior pleural disease.

Femoral nerve compression caused by a hibernoma in the right thigh: a case report and literature review

BACKGROUND

A hibernoma, also known as a brown fat tumor, is a rare benign soft tissue tumor, which originates from brown adipose tissue remaining in the fetus after the gestational period. It is often detected in adult men, presenting as a painless slow-growing mass. Hibernomas of the thigh have been reported; however, motor and sensory disorders caused by the tumors compressing the femoral nerve have not been reported. We report a case of a histopathologically proven hibernoma that induced femoral mononeuropathy.

CASE PRESENTATION

A 26-year-old man was admitted to the hospital due to a mass, approximately 11.0 × 9.0 × 4.0 cm in size, that had developed 5 years ago in the anterolateral aspect of the proximal thigh. Furthermore, he had a history of hypoesthesia 1 month prior to his admission. He had signs and symptoms of both a motor and sensory disorder, involving the anterior aspect of the right thigh and the medial aspect of the calf, along the distribution of the femoral nerve. During surgery, the femoral nerve was found to be compressed by the giant tumor. The resultant symptoms probably caused the patient to seek medical care. Marginal resection of the mass was performed by careful dissection, and the branches of the femoral nerve were spared. Histopathology examination showed findings suggestive of a hibernoma. At the 4-month follow-up, no femoral nerve compression was evident, and local tumor recurrence or metastasis was not found.

CONCLUSIONS

Asymptomatic hibernomas do not require treatment; however, in cases of hibernomas with apparent symptoms, complete marginal surgical excision at an early stage is a treatment option because it is associated with a low risk of postoperative tumor recurrence.

BNCT for primary synovial sarcoma

Synovial sarcoma is a rare tumor requiring new treatment methods. A 46-year-old woman with primary monophasic synovial sarcoma in the left thigh involving the sciatic nerve, declining surgery because of potential dysfunction of the affected limbs, received two courses of BNCT. The tumor thus reduced was completely resected with no subsequent recurrence. The patient is now able to walk unassisted, and no local recurrence has been observed, demonstrating the applicability of BNCT as adjuvant therapy for synovial sarcoma. Further study and analysis with more experience accumulation are needed to confirm the real impact of BNCT efficacy for its application to synovial sarcoma.

What Are the Results of Resection of Localized Dedifferentiated Liposarcomas in the Extremities?

BACKGROUND

Dedifferentiated liposarcoma (DDLPS) is a rare malignancy that transitions from an atypical lipomatous tumor to a sarcoma with a variable morphologic appearance. The behavior of this tumor in the retroperitoneum is aggressive, but the behavior of DDLPS in the extremities is less well-defined because it is rare. Few reports have assessed the imaging features and clinical outcomes of primary DDLPS in the extremities.

QUESTIONS/PURPOSES

In patients with primary DDLPS of the extremity, we asked the following questions: (1) How frequently do additional primary malignancies occur in patients with DDLPS? (2) What is the rate of overall survival, metastases, and local recurrence in DDLPS? (3) What factors are associated with metastasis-free survival and local recurrence in DDLPS?

METHODS

We defined DDLPS as a biphasic neoplasm that transitions from an atypical lipomatous tumor (ALT) to a sarcoma of variable morphologic appearance and histologic grades. We retrospectively evaluated the medical records of patients with DDLPS of the extremities who underwent surgery in our institution between 2003 and 2017. During that time, 16 patients were treated for this diagnosis; one was excluded from this study because the patient did not have an MRI, leaving 15 patients (nine men, six women; their median [range] age was 67 years [42 to 87]) for evaluation. All had a minimum of 2 years follow-up (median [range] 54 months [25 to 136]); 14 of 15 have been seen in the last 5 years (one patient, who was doing well at the time, was lost after 9 years of follow-up). In 11 patients, MRI demonstrated two components: an ALT component with high intensity on both T1-weighed and T2-weighted sequences and a dedifferentiated component low-to-intermediate intensity on T1-weighed and heterogeneous hyperintensity on T2-weighted sequence. Nine patients were evaluated using 2-deoxy-2-18F-fluoro-D-glucose positron emission tomography (FDG-PET) combined with CT (PET/CT). PET/CT showed a biphasic pattern with a close relationship to MRI findings. The dedifferentiated component presented with high FDG uptake (median [range] maximum standardized uptake value 5.1 [1.9 to 22.6]), while the atypical lipomatous tumor component showed almost no FDG uptake. In all patients, immunohistochemical studies of p16 and cyclin-dependent kinase-4 (CDK4) were investigated. Positive staining for both p16 and CDK4 were seen in 13 of 15 patients.We retrospectively evaluated the electronic medical records of all patients in our institution for the presence of additional primary malignancies, local recurrence-free survival, metastasis-free survival, and overall survival. The survival rate was estimated using the Kaplan-Meier method. The Wilcoxon exact test was used to determine the prognostic importance of the following survival variables: age, sex, maximum tumor size, radiotherapy, and surgical margin.

RESULTS

Seven additional primary malignancies developed in five of 15 patients (two lung cancers, two sarcomas, one renal cell cancer, one uterine cancer, and one non-Hodgkin lymphoma). The 3- and 5-year metastasis-free survival rates were 86% (95% CI 0.67 to 1.00) and 75% (95% CI 0.49 to 1.00), respectively. With the numbers available, we found no factors associated with metastasis-free survival. The 3- and 5-year overall survival rates were 100% (95% CI 1.00 to 1.00) and 88% (95% CI 0.65 to 1.00), respectively. Three of 15 patients had local recurrence. The 3- and 5-year local recurrence-free survival rates were 86% (95% CI 0.67 to 1.00) and 75% (95% CI 0.49 to 1.00), respectively. Large (> 15 cm) tumors were more likely to have a local recurrence (p = 0.04).

CONCLUSIONS

In this small series, we found that the extremities are a favorable site for DDLPS compared with the retroperitoneum, although we did not directly compare the two sites. This rare tumor has a relatively high likelihood of being associated with other malignancies. We believe patients should be assessed and monitored carefully for this possibility. In the future, larger studies are needed to better define predictors of local recurrence, although the tumor's size may be associated with a greater propensity for local recurrence.

LEVEL OF EVIDENCE

Level II, prognostic study.

Optimization of the Therapeutic Approach to Patients with Sarcoma: Delphi Consensus

Soft tissue sarcomas (STS) constitute a heterogeneous group of rare solid tumors associated with significant morbidity and mortality. The evaluation and treatment of STS require a multidisciplinary team with extensive experience in the management of these types of tumors. National and international clinical practice guidelines for STS do not always provide answers to a great many situations that specialists have to contend with in their everyday practice. This consensus provides a series of specific recommendations based on available scientific evidence and the experience of a group of experts to assist in decision-making by all the specialists involved in the management of STS.

PET in the Diagnostic Management of Soft Tissue Sarcomas of Musculoskeletal Origin

Soft tissue sarcomas (STSs) account for less than 1% of adult solid tumors and about 7% of pediatric malignancies, causing 2% of cancer-related deaths. With the advent of PET-computed tomography (CT), the value of (18) fluorine-2-fluoro-2-deoxy-d-glucose (FDG) PET imaging to improve the management of STSs has been explored. FDG PET imaging has been found useful in restaging and treatment response assessment. This article reviews current knowledge and application of FDG PET-CT in initial diagnosis, staging, restaging, treatment response monitoring, and prognosis, with a brief overview of the most common histologic subtypes of STS.

Hibernoma: a rare benign soft tissue tumour resembling liposarcoma

Hibernoma is a rare benign soft tissue tumour that can mimic a liposarcoma on radiographic imaging. Our case series review illustrates the clinical presentation and radiographic appearances of four patients with histologically confirmed hibernoma. Hibernoma is usually hypointense relative to subcutaneous fat on T₁ weighted MRI and demonstrates partial fat suppression on fat-saturated sequences. Large intratumoral vessels likely support the diagnosis of hibernoma but are not invariably present. Fludeoxyglucose avidity on PET scan is not beneficial in distinguishing hibernoma from soft tissue malignancy because of its inherent, metabolically active property. Owing to the radiographic heterogeneity of hibernoma, it is currently not possible to diagnose hibernoma based on imaging characteristics alone. Given the excellent prognosis of hibernoma with marginal excision alone, an appreciation of the radiographic features is helpful in the appropriate pre-operative workup of soft tissue tumours.

Hibernoma Showing High Uniform Accumulation on an 18F-Fluorodeoxyglucose Positron Emission Tomography Scan: A Case Report

Background

Hibernoma is a rare, benign, soft tissue tumor arising from brown fat that cannot be distinguished from other lipogenic tumors on computed tomography and magnetic resonance imaging (MRI) scans. On the other hand, the image of hibernoma on ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG-PET) is different from that of other lipogenic tumors. However, fewer studies have investigated the typical features of hibernoma on PET scans. We present the case of a hibernoma that was incidentally detected on ¹⁸F-FDG-PET.

Case Presentation

A 48-year-old Asian man underwent ¹⁸F-FDG-PET for routine follow-up of gastric cancer. The patient reported a painless soft mass on the upper arm that had persisted for several years. On ¹⁸F-FDG-PET, the mass showed a maximum standardized uptake value of 9.6. The mass showed high intensity on T1- and T2-weighted MRI scans, and showed focally enhanced septa after gadolinium administration. The mass was surgically resected. Histopathologically, the mass was composed of brown adipose cells characteristic of hibernoma. His postoperative course was uneventful, and there was no local recurrence at the final 24-month follow-up.

Conclusion

Hibernoma showed strong uniform accumulation on ¹⁸F-FDG-PET, suggesting that ¹⁸F-FDG-PET would be a useful modality for the differential diagnosis of hibernoma versus other lipogenic tumors.

Prognostic significance of (18)F-FDG PET at diagnosis in patients with soft tissue sarcoma and bone sarcoma; systematic review and meta-analysis

PURPOSE

The usefulness of (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) for the survival prognosis in soft tissue sarcoma (STS) and bone sarcoma (BS) is controversial. The objective of this systematic review was to provide an up-to-date and unprecedented summary of the prognostic value of (18)F-FDG PET at diagnosis in STS and BS.

METHODS

Studies evaluating pre-treatment (18)F-FDG PET for overall survival of STS and BS were systematically searched for in MEDLINE, EMBASE, and Web of Science. Comparative analyses of the pooled hazard ratios (HR) of overall survival were performed between patients with high and low maximum standardised uptake value (SUVmax). The quality of study designs was evaluated using the Newcastle-Ottawa scale (NOS) for quality assessment of cohort studies. P < 0.05 was defined as statistically significant.

RESULTS

A total of six studies comprising 514 patients with STS and BS were considered for the meta-analysis. The pooled HR for overall survival was 1.22 (95% confidence interval: 1.03-1.46), suggesting that high SUVmax predicts a significantly shorter overall survival period than low SUVmax (P = 0.03). Additional subgroup analyses using patients with STS alone showed that high SUVmax might predict poorer overall survival than low SUVmax (P = 0.004), although only two studies consisting of 96 patients were included. The overall quality of the included studies evaluated by the NOS assessment was adequate.

CONCLUSION

(18)F-FDG PET at diagnosis provides a very useful predictive tool for patients with STS and BS.