Liposarcoma of the extremities: MR imaging features and their correlation with pathologic data

SummaryObjectiveTo describe the MRI features of liposarcomas of the extremities and correlate them with data from the histologic subtypes.Material and methodsRetrospective study of 20 cases of liposarcoma of the extremities identified on MRI, surgically removed and confirmed at pathology. On MRI examination, T1- and T2-weighted fat-suppressed and non-fat-suppressed images were acquired then gadolinium-enhanced fat-suppressed T1-weighted images were obtained in at least two orthogonal planes.ResultsSixteen female and four male patients aged 12 to 77 years old at presentation, in 16 cases, with a slowly enlarging painless mass (demonstrating no associated local or general inflammatory components), located in the lower extremity (16 cases) and predominantly located in the thigh (13 cases). Pathologic examination revealed three cases of well-differentiated liposarcoma, 12 cases of myxoid liposarcoma one of which with round cells, three cases of pleomorphic liposarcoma, one case of dedifferentiated liposarcoma and one case of mixed-type liposarcoma. MR images mostly showed well-circumscribed tumors (19 cases) . Well-differentiated liposarcomas typically demonstrated a very specific diagnostic appearance as a predominantly adipose mass containing nonlipomatous components seen as thick septa that may show nodularity. Other subtypes of liposarcoma demonstrated a small amount of adipose tissue thus producing a marbled textural pattern on T1-weighted images particularly in myxoid liposarcomas (9 cases), or even nonlipomatous elements in high-grade liposarcomas (in round cell liposarcoma and in two out of three pleomorphic liposarcomas). The myxoid subtype has also a relatively characteristic appearance as a low signal intensity noted on T1-weighted images and a marked high signal intensity on T2. The dedifferentiated liposarcoma has a very specific radiologic appearance as a nonlipomatous component within a predominantly adipose mass, simulating that of well-differentiated liposarcomas.ConclusionMRI of extremity liposarcomas is a highly reliable and sensitive method to characterize liposarcomas. Besides its value in the diagnosis of liposarcoma and locoregional extension control, it allows proper identification of the specific histologic subtypes of liposarcoma.Level of evidenceLevel IV. Rétrospective diagnostic study

Performance comparison of inverter control techniques used for the supply of a linear PM synchronous actuator

This paper presents performance comparison of three inverter control techniques. These techniques are respectively hysteresis control, MAIM control and direct voltage control (DVC). They are applied for a PM Linear Tubular Synchronous Actuator (PAITI,SA) drive fed, using a three phase voltage source inverter (VSI). This VSI is working with constant switching time intervals as in the standard torque control DTC system

Identification of c.483C>T polymorphism in the caprine Tyrosinase-related protein 1(TYRP1) gene

Tyrosinase-related protein 1 (TYRP1) has been shown to play a fundamental role in pigmentation both in human and mouse. In this work, we aimed to characterize the variability of the caprine TYRP1 gene and investigate its segregation in a wide array of goat breeds. By partially sequencing the coding region of the TYRP1 gene in 18 individuals from eight different breeds, we were able to identify a synonymous nucleotide substitution at exon 3 (c.483C>T). An extensive survey of Iberian and Balearic (N=175), Italian (N=99), Swiss (N=54), Asian (N=14), Canarian (N=92) and North African (N=117) goats with different coat colours was carried out. We found that the C-allele has a different distribution in European vs African breeds, being almost fixed in the latter. Moreover, the C-allele showed an increased frequency in white coated breeds (Girgentana, Grigia Molisana, Blanca de Rasquera and Saanen) when compared with those displaying a dark pigmentation (Cilentana Nera, Azpi Gorri and Murciano-Granadina). This could be due to genetic drift, migration and other factors associated with the demographic history of breeds under analysis or to a genetic hitchhiking event (c.483C>T frequencies would be shaped by a neighbouring causal mutation differentially selected in white and black goats). More refined studies will be needed to distinguish between these two alternative explanations. © B. Badaoui et al., 2012

Technical note: Advantages and limitations of authenticating Palmera goat dairy products by pyrosequencing the melanocortin 1 receptor (MC1R) gene

Inferring the breed of origin of dairy products can be achieved through molecular analysis of genetic markers with a population-specific pattern of segregation. The goal of the current work was to generate such markers in goats by resequencing several pigmentation genes [melanocortin 1 receptor (. MC1R), v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog (. KIT), tyrosinase (. TYR), and tyrosinase-related protein 2 (. TYRP2)]. This experiment revealed 10 single nucleotide polymorphisms (SNP), including 5 missense mutations and 1 nonsense mutation. These markers were genotyped in 560 goats from 18 breeds originally from Italy, the Iberian Peninsula, the Canary Islands, and North Africa. Although the majority of SNP segregated at moderate frequencies in all populations (including 2 additional markers that were used as a source of information), we identified a c.764G>A SNP in MC1R that displayed highly divergent allelic frequencies in the Palmera breed compared with the Majorera and Tinerfeña breeds from the Canary Islands. Thus, we optimized a pyrosequencing-based technique that allowed us to estimate, very accurately, the allele frequencies of this marker in complex DNA mixtures from different individuals. Once validated, we applied this method to generating breed-specific DNA profiles that made it possible to detect fraudulent cheeses in which Palmero cheese was manufactured with milk from Majorera goats. One limitation of this approach, however, is that it cannot be used to detect illegal manufacturing where Palmero dairy products are produced by mixing milk from Palmera and Majorera goats, because the c.764G>A SNP segregates in both breeds