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A major cytogenetic subgroup among human lipomas is characterized by translocations involving the HMGIC gene at 12q15. In the context of an ongoing research program aiming at the elucidation of the functional consequences of HMGIC translocations in the etiology of lipomas, we have isolated a novel human gene, LHFP (lipoma HMGIC fusion partner), that acts as a translocation partner of HMGIC in a lipoma with t(12;13). The LHFP gene was mapped to the long arm of chromosome 13, a region recurrently targeted by chromosomal aberrations in lipomas. By Northern blot analysis, a transcript of 2. 4 kb was detected in a variety of human tissues. We assembled a cDNA contig containing the entire coding region of LHFP. Nucleotide sequence analysis of the composite LHFP cDNA revealed an open reading frame encoding a protein of 200 amino acids. The predicted human LHFP protein is almost identical to a translated mouse EST that covers almost the entire LHFP coding region. In addition, BLAST searches revealed that the LHFP protein belongs to a new protein family consisting of at least four or five members. In the lipoma studied, the expressed HMGIC/LHFP fusion transcript encodes the three DNA binding domains of HMGIC followed by 69 amino acids encoded by frame-shifted LHFP sequences. LHFP is the second translocation partner of HMGIC identified in lipomas and represents a candidate target gene for lipomas with 13q aberrations.

The anatomical and functional status of the epifascial and subfascial lymphatic compartments was analyzed using two compartment lymphoscintigraphy in five groups of patients (total 55) with various forms of edema of the lower extremities. Digital whole body scintigraphy enabled semiquantitative estimation of radiotracer transport with comparison of lymphatic drainage between those individuals without (normal) and those with leg edema by calculating the uptake of the radiopharmaceutical transported to regional lymph nodes. A visual assessment of the lymphatic drainage pathways of the legs was also performed. In patients with cyclic idiopathic edema, an accelerated rate of lymphatic transport was detected (high lymph volume overload or dynamic insufficiency). In those with venous (phlebo) edemas, high volume lymphatic overload (dynamic insufficiency) of the epifascial compartment was scintigraphically detected by increased tracer uptake in regional nodes. In patients with deep femoral venous occlusion (post-thrombotic syndrome). subfascial lymphatic transport was uniformly markedly reduced (safety valve lymphatic insufficiency). On the other hand, in the epifascial compartment, lymph transport was accelerated. In those patients with recurrent or extensive skin ulceration, lymph transport was reduced. Patients with lipedema (obesity) scintigraphically showed no alteration in lymphatic transport. This study demonstrates that lymphatic drainage is notably affected (except in obesity termed lipedema) in various edemas of the leg. Lymphatic drainage varied depending on the specific compartment and the pathophysiologic mechanism accounting for the edema. Two compartment lymphoscintigraphy is a valuable diagnostic tool for accurate assessment of leg edema of known and unknown origin.

The anatomical and functional status of the epifascial and subfascial lymphatic compartments was analyzed using two compartment lymphoscintigraphy in five groups of patients (total 55) with various forms of edema of the lower extremities. Digital whole body scintigraphy enabled semiquantitative estimation of radiotracer transport with comparison of lymphatic drainage between those individuals without (normal) and those with leg edema by calculating the uptake of the radiopharmaceutical transported to regional lymph nodes. A visual assessment of the lymphatic drainage pathways of the legs was also performed. In patients with cyclic idiopathic edema, an accelerated rate of lymphatic transport was detected (high lymph volume overload or dynamic insufficiency). In those with venous (phlebo) edemas, high volume lymphatic overload (dynamic insufficiency) of the epifascial compartment was scintigraphically detected by increased tracer uptake in regional nodes. In patients with deep femoral venous occlusion (post-thrombotic syndrome). subfascial lymphatic transport was uniformly markedly reduced (safety valve lymphatic insufficiency). On the other hand, in the epifascial compartment, lymph transport was accelerated. In those patients with recurrent or extensive skin ulceration, lymph transport was reduced. Patients with lipedema (obesity) scintigraphically showed no alteration in lymphatic transport. This study demonstrates that lymphatic drainage is notably affected (except in obesity termed lipedema) in various edemas of the leg. Lymphatic drainage varied depending on the specific compartment and the pathophysiologic mechanism accounting for the edema. Two compartment lymphoscintigraphy is a valuable diagnostic tool for accurate assessment of leg edema of known and unknown origin.

Lipoedema is a common but infrequently recognized condition causing bilateral enlargement of the legs in women. Although generally considered to be the result of an abnormal deposition of subcutaneous fat with associated oedema, the precise mechanisms responsible for oedema formation have yet to be fully established. In order to evaluate the possible role of lymphatic or venous dysfunction in the pathogenesis of lipoedema, 10 patients were investigated by photoplethysmography (venous function) and quantitative lymphoscintigraphy (lymphatic function). The results were compared with those from patients with primary lymphoedema and those from healthy volunteers. The results demonstrated minor abnormalities of venous function in only two patients. One patient had moderately impaired lymphatic function in both legs and seven patients had a marginal degree of impairment in one or both legs. However, in none of these cases did the impairment attain the low levels seen in true lymphoedema. Lipoedema appears to be a distinct clinical entity best classified as a lipodystrophy rather than a direct consequence of any primary venous or lymphatic insufficiency.

PURPOSE: Lymphoscintigraphy has emerged as the diagnostic test of choice in patients with suspected lymphedema. To assess the lymphatic circulation of 386 extremities in 188 patients, we prospectively recorded a semiquantitative index of lymphatic transport in addition to visual evaluation of lymphoscintigraphy image patterns. METHODS: Sixty-one male and 127 female patients were studied (mean age 48 years, range 13 to 87 years). Twenty had upper extremity swelling, and 168 had lower extremity swelling. The disease was bilateral in 60 patients. Lymphoscintigraphy was performed by injecting a mean of 503 microCi of technetium 99m-antimony trisulfide colloid subcutaneously into the second interdigital space of the extremity. Time for transport to regional lymph nodes, appearance of lymph vessels and nodes and distribution pattern were scored. These scores were compiled into a modified Kleinhans transport index (TI). To assess the venous circulation, 155 patients underwent evaluation of the venous system by impedance plethysmography, ultrasonography, or contrast venography. RESULTS: The mean TI (+/- SEM) in 79 asymptomatic extremities was 2.6 +/- 0.5, with 66 (83.5%) demonstrating normal lymphoscintigraphy pattern (TI < 5). Patients with clinical diagnosis of lymphedema (n = 124) had a mean TI of 23.8 +/- 1.5; 81.5% of these were greater than 5. Fifty-six patients (30%) had primary and 68 (36%) had secondary lymphedema. (TI of 26 +/- 3.5 and 22.1 +/- 1.9, respectively, p = NS). Patients without any lymphatic transport (TI of 45) were more likely to have cellulitis in their history (p < 0.05). Contrast lymphangiography in six patients correlated with lymphoscintigraphy. Sixty-four patients (34%) had swelling without lymphedema (venous edema, cardiac edema, lipedema, etc.; TI of 1.9 +/- 0.4, p < 0.001). Of the 41 patients with abnormal venous studies, 18 (44%) had an elevated TI. CONCLUSIONS: Semiquantitative evaluation of the lymphatic transport with lymphoscintigraphy reliably depicts abnormalities in the lymphatic circulation. Lymphoscintigraphy excluded lymphedema as a cause of leg swelling in one third of our patients.

The authors assessed the use of magnetic resonance imaging in differentiating lymphedema, phlebedema, and lipedema of the lower limb. They examined 14 patients: five with lipedema, five with lymphedema, and four with phlebedema. T1- and T2-weighted transaxial sequences were performed before administration of gadolinium tetraazacyclododecane-tetraacetic acid (DOTA) and T1-weighted spin-echo sequences were performed after administration of Gd-DOTA in each patient. Images of patients with lipedema showed homogeneously enlarged subcutaneous layers, with no increase in signal intensity at T2-weighted imaging or after Gd-DOTA administration. Patients with phlebedema had areas containing increased amounts of fluid within muscle and subcutaneous fat. In lymphedema, a honeycomb pattern above the fascia between muscle and subcutis was observed, with a marked increase in signal intensity at T2-weighted imaging. After Gd-DOTA administration, there was only a slight increase in signal intensity in the subcutis in lymphedema and phlebedema and a moderate increase in signal intensity in muscle in phlebedema.

The use of a single axial slice through the mid calf in the differential diagnosis of a swollen leg is described. This is a very simple quick non-invasive investigation. Venous obstruction results in an increase in the cross sectional area of the muscle compartment. The subcutaneous fat layer is normally homogeneous; in obesity or lipoedema it is increased but remains homogeneous. In lymphoedema fluid collects in the interstitial spaces which become very prominent on CT images. In chronic lymphoedema a honeycomb pattern is seen as a result of increase in the interstitial tissue due to fibrosis. Popliteal cyst extensions result in fluid collections between muscle planes. Haematomas have higher attenuation, and are intramuscular. The findings in 64 patients and 10 controls are presented and the literature is reviewed.