Histology and imaging of soft tissue sarcomas

Intramuscular mesenchymal chondrosarcoma surrounded by a split fat sign mimicking a benign lesion

Mesenchymal chondrosarcoma (MCS) is an aggressive malignant mesenchymal tumour of uncertain differentiation. This is rare, accounting for 2%-4% of chondrosarcomas. Its peak incidence is in the second and third decades, though it can occur at any age. These tumours show a widespread distribution, mainly in bone, but with approximately 40% affecting somatic soft tissue. We present a case of MCS arising within the soleus muscle. The lesion was surrounded by a split-fat sign/fatty rind which is a typical feature of peripheral nerve sheath tumours or other benign intramuscular tumours. However, percutaneous biopsy showed MCS. We highlight how perilesional fat is not exclusive to benign intramuscular lesions and, although much less common, can be associated with malignant lesions. This is, to the best of our knowledge, the first reported case of MCS presenting with a split-fat sign at MRI.

Pathological Thoracic Vertebral Fractures Secondary to Achromobacter denitrificans: A Case Report

Vertebral fractures remain a diagnostic challenge nowadays. The first and most common diagnosis needed to be ruled out is osteoporosis. Other diagnoses to rule out involve pathological fractures. Pathological fractures are a group of pathologies that result in a spine fracture as part of an underlying disease process that affects the spine. This group includes Paget's disease, tumors, osteomyelitis, and vertebral compression fractures. Fractures secondary to vertebral osteomyelitis are presented as collapsed vertebral bodies secondary to bone destruction and the formation of lytic lesions. Clinical presentation includes severe back pain refractory to analgesic therapy, persistent unexplained fever, and leukocytosis without any other obvious focus of infection. In cases like the one presented here, early biopsy and culture should be performed on every patient that fits these criteria. However, as it presents unspecific symptoms most of the time, it is not suspected, and therefore it is associated with high morbidity and mortality.

Elastofibroma Dorsi: Case Series of a Rare Chest Wall Pseudotumor

BACKGROUND

Elastofibroma dorsi (EFD) is a pseudotumor of the thoracic wall that can be difficult to diagnose due to its rarity. Prompt recognition can limit unnecessary workup and expedite treatment. This study retrospectively analyzed patients with a diagnosis of EFD, discussing clinical presentations and surgical outcomes.

METHODS

This is an IRB-approved single-center retrospective study of all patients with a diagnosis of elastofibroma at our institution between 2000 and 2022.

RESULTS

Ten patients were identified to have a pathologic diagnosis of EFD since 2000, with half presenting in the last 5 years. Our cohort had an average age of 56.8 years and was 50% female. The average age of male subjects was younger than females, 49.6-64.0 years, respectively (p = 0.10). Eighty percent (8/10) of patients had unilateral EFDs and symptoms lasted 27.1 months on average prior to diagnosis. Surgical resection was performed on 66.67% (8/12) of masses, with 87.5% (7/8) of patients who underwent surgery reporting complete resolution of their symptoms and none reporting recurrence.

CONCLUSIONS

Although EFD is a rare pseudotumor, its incidence may be increasing. As such, surgeons should be aware of the typical clinical presentation; specifically, a slow growing, predominantly unilateral, painful, subscapular mass with an inhomogeneous pattern on imaging. Originally thought to predominantly affect elderly women, our study shows that younger men may be at risk as well. If patients present with EFD, complete surgical resection should be performed to achieve favorable outcomes and resolution of symptoms.

Ensemble learning-based radiomics with multi-sequence magnetic resonance imaging for benign and malignant soft tissue tumor differentiation

Many previous studies focused on differentiating between benign and malignant soft tissue tumors using radiomics model based on various magnetic resonance imaging (MRI) sequences, but it is still unclear how to set up the input radiomic features from multiple MRI sequences. Here, we evaluated two types of radiomics models generated using different feature incorporation strategies. In order to differentiate between benign and malignant soft tissue tumors (STTs), we compared the diagnostic performance of an ensemble of random forest (R) models with single-sequence MRI inputs to R models with pooled multi-sequence MRI inputs. One-hundred twenty-five STT patients with preoperative MRI were retrospectively included and consisted of training (n = 100) and test (n = 25) sets. MRI included T1-weighted (T1-WI), T2-weighted (T2-WI), contrast-enhanced (CE)-T1-WI, diffusion-weighted images (DWIs, b = 800 sec/mm2) and apparent diffusion coefficient (ADC) maps. After tumor segmentation on each sequence, 100 original radiomic features were extracted from each sequence image and divided into three-feature sets: T features from T1- and T2-WI, CE features from CE-T1-WI, and D features from DWI and ADC maps. Four radiomics models were built using Lasso and R with four combinations of three-feature sets as inputs: T features (R-T), T+CE features (R-C), T+D features (R-D), and T+CE+D features (R-A) (Type-1 model). An ensemble model was built by soft voting of five, single-sequence-based R models (Type-2 model). AUC, sensitivity, specificity, and accuracy of each model was calculated with five-fold cross validation. In Type-1 model, AUC, sensitivity, specificity, and accuracy were 0.752, 71.8%, 61.1%, and 67.2% in R-T; 0.756, 76.1%, 70.4%, and 73.6% in R-C; 0.750, 77.5%, 63.0%, and 71.2% in R-D; and 0.749, 74.6%, 61.1%, and 68.8% R-A models, respectively. AUC, sensitivity, specificity, and accuracy of Type-2 model were 0.774, 76.1%, 68.5%, and 72.8%. In conclusion, an ensemble method is beneficial to incorporate features from multi-sequence MRI and showed diagnostic robustness for differentiating malignant STTs.

Trigger finger at the wrist caused by an intramuscular lipoma within the carpal tunnel: A case report

BACKGROUND

Trigger finger at the wrist, which occurs with finger movement, is an uncommon presentation. Few reports describing cases of trigger finger at the wrist have been published. Thus, we present a case of an intramuscular lipoma arising from an anomalous flexor digitorum muscle belly in a 48-year-old female patient causing painful finger triggering at the wrist and carpal tunnel syndrome (CTS).

CASE SUMMARY

A 48-year-old woman with complaints of a catching sensation during wrist motion and a progressive tingling sensation on the palmar aspect of the right hand for approximately 2 years was referred to our hospital. Triggering of the index to middle finger was evident with a palpable and audible clunk over the carpal tunnel during passive motion. Tinel’s sign was positive over the carpal tunnel of the right wrist with a positive Phalen’s test. Nerve conduction studies of the median nerve demonstrated a right CTS. Ultrasound examination revealed a 2.5 cm × 2.0 cm subcutaneous hyperechoic mass with no obvious blood flow at the wrist of the right arm. Surgical excision of the tumor and muscle mass led to a resolution of the patient’s symptoms, and any triggering or discomfort disappeared. The patient has had no evidence of recurrence at more than 1 year of follow-up.

CONCLUSION

Triggering of the fingers at the wrist is rare. It must be noted that there are many possible causes and types of triggering or clicking around the wrist. Accurate diagnosis is mandatory to avoid inaccurate treatment of patients with trigger wrist. During the diagnosis and treatment of CTS, attention should be paid to the variation of tendon tissue in the carpal tunnel, to avoid only focusing on the release of transverse carpal ligament and ignoring the removal of anomalous muscle belly.

Micro-CT for Biological and Biomedical Studies: A Comparison of Imaging Techniques

Several imaging techniques are used in biological and biomedical studies. Micro-computed tomography (micro-CT) is a non-destructive imaging technique that allows the rapid digitisation of internal and external structures of a sample in three dimensions and with great resolution. In this review, the strengths and weaknesses of some common imaging techniques applied in biological and biomedical fields, such as optical microscopy, confocal laser scanning microscopy, and scanning electron microscopy, are presented and compared with the micro-CT technique through five use cases. Finally, the ability of micro-CT to create non-destructively 3D anatomical and morphological data in sub-micron resolution and the necessity to develop complementary methods with other imaging techniques, in order to overcome limitations caused by each technique, is emphasised.

Elastofibroma dorsi: a case report of bilateral occurrence and review of literature

BACKGROUND

Elastofibroma dorsi (ED) is a benign slow growing soft tissue tumor that is most frequently located subscapular. The prevalence is estimated to be 2% on imaging studies in individuals over 60 years old and might occur bilaterally. The etiology, however, remains unclear.

CASE PRESENTATION

This report presents the case of a man with bilateral ED. He first presented at the age of 49 with a subscapular ED on the right side and again at the age of 53 with a subscapular ED on the left side. At both times, diagnosis of ED was histopathologically confirmed after surgical resection. And, again at both times, the postoperative course was characterized by seroma development.

DISCUSSION

This report shows a brief review of literature on ED. It contains a summary of the current data on prevalence, etiology, clinical presentation, diagnosis, histopathological findings, surgical treatment and postoperative management. It also includes a flowchart for diagnostic and therapeutic approach.

CONCLUSIONS

ED might present bilaterally, though not necessarily affecting both sides simultaneously. In order to diagnose ED MRI is ought to be sufficient. Invasive procedures, i.e. complete surgical excision, are mandatory to treat symptomatic ED, although such surgical procedures are often complicated by seroma formation.

Small Subcutaneous Soft Tissue Tumors (<5 cm) Can Be Sarcomas and Contrast-Enhanced Ultrasound (CEUS) Is Useful to Identify Potentially Malignant Masses

Subcutaneous masses smaller than 5 cm can be malignant, in contrast with the international guidelines. Ultrasound (US) and magnetic resonance imaging (MRI) are useful to distinguish a potentially malignant mass from the numerous benign soft tissue (ST) lesions. Contrast-enhanced ultrasound (CEUS) was applied in ST tumors, without distinguishing the subcutaneous from the deep lesions. We evaluated CEUS and MRI accuracy in comparison to histology in differentiating malignant from nonmalignant superficial ST masses, 50% smaller than 5 cm. Sensitivity, specificity, and positive and negative predictive values (PPV, NPV) with their 95% confidence intervals (CI) were calculated. Of malignant cases, 44.4% measured ≤5 cm. At univariate analysis, no statistically significant differences emerged between benign and malignant tumors in relation with clinical characteristics, except for relationship with the deep fascia (p = 0.048). MRI accuracy: sensitivity 52.8% (CI 37.0, 68.0), specificity 74.1% (CI 55.3, 86.8), PPV 73.1% (CI 53.9, 86.3), and NPV 54.1% (CI 38.4, 69.0). CEUS accuracy: sensitivity 75% (CI 58.9, 86.3), specificity 37% (CI 21.5, 55.8), PPV 61.4% (CI 46.6, 74.3), and NPV 52.6% (CI 31.7, 72.7). CEUS showed a sensitivity higher than MRI, whereas PPV and NPV were comparable. Also, masses measuring less than 5 cm can be malignant and referral criteria for centralization could be revised.

Elastofibroma dorsi: What's new?

Elastofibroma dorsi is a rare slowgrowing soft tissues tumor. The lesion usually grows near the shoulder but could also involve other location. Pathogenesis of elastofibroma dorsi is still unknown and in the literature, there are mostly described case report or case series. The aim of our study is to summarize the recent innovation in the histology and immunoistochemical finding about elastofibroma and update the radiological algorithm of diagnosis.

Intramuscular Lipoma of the Flexor Hallucis Brevis MuscleA Case Report

An intramuscular lipoma is a deep-seated, rare, benign mesenchymal tumor that arises in skeletal muscle. These soft-tissue masses are rarely reported in the foot. We describe an unusual case of an intramuscular lipoma of the flexor hallucis brevis muscle. A review of the literature revealed only one previous report of this lesion in the foot.

Soft tissue hemangioma with osseous extension: a case report and review of the literature

Soft tissue hemangiomas are commonly encountered lesions, accounting for 7-10 % of all benign soft tissue masses (Mitsionis et al. J Foot Ankle Surg 16(2):27-9, 2010). While the literature describes the great majority of hemangiomas as asymptomatic and discovered only as incidental findings, they do have the potential to induce reactive changes in neighboring structures (Pastushyn et al. Surg Neurol 50(6):535-47, 1998). When these variants occur in close proximity to bone, they may elicit a number of well-documented reactive changes in osseous tissue (Mitsionis et al. J Foot Ankle Surg 16(2):27-9, 2010; DeFilippo et al. Skelet Radiol 25(2):174-7, 1996; Ly et al. AJR Am J Roentgenol 180(6):1695-700, 2003; Sung et al. Skelet Radiol 27(4):205-10, 1998). However, instances of direct extension into bone by soft tissue hemangiomas--that is, infiltration of the mass's vascular components into nearby osseous tissue--are currently undocumented in the literature. In these cases, imaging plays an important role in differentiating hemangiomas from malignant lesions (Mitsionis et al. J Foot Ankle Surg 16(2):27-9, 2010; Sung et al. Skelet Radiol 27(4):205-10, 1998; Pourbagher, Br J Radiol 84(1008):1100-8, 2011). In this article, we present such a case that involved the sacral spine. Imaging revealed a soft tissue mass with direct extension of vascular components into osseous tissue of the adjacent sacral vertebrae. Biopsy and subsequent histopathologic examination led to definitive diagnosis of soft tissue hemangioma. While MRI is widely regarded as the gold standard imaging modality for evaluating hemangiomas, in this report we describe how CT can aid in narrowing the differential diagnosis when one encounters a vascular lesion with adjacent osseous changes. Furthermore, we review the literature as it pertains to the imaging of soft tissue hemangiomas that occur in proximity to osseous tissue, as well as correlate this case to current theories on the pathogenesis of hemangiomas. Radiologists should be aware that benign soft tissue hemangiomas demonstrate a spectrum of imaging findings, including aggressive-appearing changes to adjacent bone.

Intramuscular lipoma of the subscapularis muscle

CONTEXT

Intramuscular lipomas are benign tumors that infiltrate the muscles.

CASE REPORT

We describe the case of a 58-year-old female patient with an axillary lump. The lump was a lipoma inside the subscapularis muscle. It is important to differentiate these lesions from liposarcomas and from other diseases that may present as axillary lumps. The most accurate imaging method for differentiating benign lipomatous tumors from liposarcomas is magnetic resonance imaging, but surgical removal of these intramuscular lesions to confirm the diagnosis is recommended.

CONCLUSION

Intramuscular lipomas are a rare cause of benign axillary lumps and should be considered in making differential diagnoses on axillary masses.

Intramuscular lipoma of the abductor digiti minimi mimicking intramuscular haemangioma

Intramuscular lipoma of the foot is rarely reported. We reported a case of intramuscular lipoma of the abductor digiti minimi mimicking intramuscular haemangioma in clinical and MR findings.

Evaluation of the relationship between extremity soft tissue sarcomas and adjacent major vessels using contrast-enhanced multidetector CT and three-dimensional volume-rendered CT angiography: a preliminary study

BACKGROUND

Accurate description of the relationship between extremity soft tissue sarcoma and the adjacent major vessels is crucial for successful surgery. In addition to magnetic resonance imaging (MRI) or in patients who cannot undergo MRI, two-dimensional (2D) postcontrast computed tomography (CT) images and three-dimensional (3D) volume-rendered CT angiography may be valuable alternative imaging techniques for preoperative evaluation of extremity sarcomas.

PURPOSE

To preoperatively assess extremity sarcomas using multidetector CT (MDCT), with emphasis on postcontrast MDCT images and 3D volume-rendered MDCT angiography in evaluating the relationship between tumors and adjacent major vessels.

MATERIAL AND METHODS

MDCT examinations were performed on 13 patients with non-metastatic extremity sarcomas. Conventional CT images and 3D volume-rendered CT angiography were evaluated, with focus on the relationship between tumors and adjacent major vessels. Kappa consistency statistics were performed with surgery serving as the reference standard.

RESULTS

The relationship between sarcomas and adjacent vessels was described as one of three patterns: proximity, adhesion, and encasement. Proximity was seen in five cases on postcontrast CT images or in eight cases on volume-rendered images. Adhesion was seen in three cases on both postcontrast CT images and volume-rendered images. Encasement was seen in five cases on postcontrast CT images or in two cases on volume-rendered images. Compared to surgical results, postcontrast CT images had 100% sensitivity, 83.3% specificity, 87.5% positive predictive value, 100% negative predictive value, and 92.3% accuracy in the detection of vascular invasion (κ = 0.843, P = 0.002). 3D volume-rendered CT angiography had 71.4% sensitivity, 100% specificity, 100% positive predictive value, 75% negative predictive value, and 84.6% accuracy in the detection of vascular invasion (κ = 0.698, P = 0.008). On volume-rendered images, all cases with adhesion or encasement had arterial stenosis and all tumors' feeding arteries were clearly depicted.

CONCLUSION

2D postcontrast CT images are superior to 3D volume-rendered CT angiography in evaluating the relationship between extremity sarcomas and adjacent major vessels. 3D volume-rendered CT angiography is good at assessing the tumor's blood supply, the longitudinal extent of vascular involvement, and the vascular narrowing due to the tumor.

Mapping protein signal pathway interaction in sarcoma bone metastasis: linkage between rank, metalloproteinases turnover and growth factor signaling pathways

We applied reverse phase protein microarrays technology to map signal pathway interactions in a discovery set of 34 soft tissue sarcoma (STS) bone metastases compared to healthy bone. Proteins associated with matrix remodeling (MMP), adhesion (FAK Y576/577, Syndecan-1), and growth/survival (IGF1R Y1135/1136, PI3K, EGFR) were elevated in metastasis compared to normal bone. Linkage between Syndecan-1, FAK Y576/577, Shc Y317, and EGFR, IGF Y1135/1136, PI3K/AKT was a prominent feature of STS bone metastasis. Elevated linkage between RANKL and 4EBP1 T37/46, EGFR, IGF1R Y1135/1136, Src Y41, Shc Y317, PI3Kp110γ was associated with short survival. Finally, we tested the hypothesis that signal pathway proteins augmented in the STS bone metastasis may provide clues to understand the subset of primary STS that metastasize. The most representative molecules identified in the discovery set were validated on an independent series of 82 primary STS by immunohistochemistry applied to a tissue microarray. The goal was to correlate the molecular profile in the primary tumors with a higher likelihood of metastasis. Elevation of activated kinase substrate endpoints IRS1 S612, 4EBP1 T37/46, FAK Y576/577 and loss of Fibronectin, were associated with a higher likelihood of metastases. These data indicate that the linkage between matrix remodeling, adhesion, and growth signaling may drive STS metastasis and can be the basis for prognostic and therapeutic strategies.

Assessment of soft tissue tumours of the extremities with diffusion echoplanar MR imaging

PURPOSE

This study assessed soft tissue tumours of the extremities with diffusion echo-planar magnetic resonance (MR) imaging.

MATERIALS AND METHODS

We carried out a retrospective study of 37 patients (22 male, 15 female; age range 4-68 years; mean age 41 years) with a soft tissue mass. Diffusion-weighted magnetic resonance (MR) imaging was done using echo-planar imaging (EPI) with b factor of 0.500 and 1,000 mm2/s. The apparent diffusion coefficient (ADC) map was reconstructed with calculation of the ADC values of the mass.

RESULTS

The mean ADC value of the malignant tumours was 1.02±0.03×10(-3)mm(2)/s and that of benign masses 1.54±0.03×10(-3)mm(2)/s. There was a significant difference in the ADC values between malignant soft tissue tumours and benign masses (p<0.001) and within different grades of malignancy (p<0.02). Selection of 1.34×10(-3) mm(2)/s as a threshold ADC value for differentiating malignant soft tissue tumours from benign masses resulted in an accuracy of 91%, sensitivity of 94%, specificity of 88% and area under the curve of 0.869. There was a significant difference in the ADC value between well- and poorly differentiated malignancies (p=0.001).

CONCLUSIONS

Diffusion-weighted echo-planar MR imaging is a promising noninvasive modality that may be helpful in differentiating malignant soft tissue tumours from benign masses as well as in grading malignancy.