Conventional Lipomas Research Articles

ANGIOLIPOMA OF LABIA MAJORA: A RARE CASE REPORT

Angiolipoma is a benign, soft tissue tumor. It is a variant of lipoma with a prominent vascular component consisting of only 6-7% of all lipomas. Though conventional lipomas are commonly found over the neck and upper back, shoulders, abdomen, buttocks, and proximal portions of the extremities, vulval lipomas are very rare and fewer than 70 cases have been reported in world literature. Herein, we report a case of angiolipoma in a 35 years old female in labia majora on account of its rarity with a review of literature. A clinical diagnosis of lipoma was provided to usby the surgeon and on the basis of histopathological examination of the excised mass, a diagnosis of angiolipoma was conferred upon. Our case report describes a rare variant of lipoma, at an uncommon location and also highlights the importance of histopathological examination in arriving at the final diagnosis.

Reduced lipolysis in lipoma phenocopies lipid accumulation in obesity

BackgroundElucidation of lipid metabolism and accumulation mechanisms is of paramount importance to understanding obesity and unveiling therapeutic targets. In vitro cell models have been extensively used for these purposes, yet, they do not entirely reflect the in vivo setup. Conventional lipomas, characterized by the presence of mature adipocytes and increased adipogenesis, could overcome the drawbacks of cell cultures. Also, they have the unique advantage of easily accessible matched controls in the form of subcutaneous adipose tissue (SAT) from the same individual. We aimed to determine whether lipomas are a good model to understand lipid accumulation.MethodsWe histologically compared lipomas and control SAT, followed by assessment of the lipidome using high-resolution 1H NMR spectroscopy and ESI-IT mass spectrometry. RNA-sequencing was used to obtain the transcriptome of lipomas and the matched SAT.ResultsWe found a significant increase of small-size (maximal axis < 70 µm) and very big (maximal axis > 150 µm) adipocytes within lipomas. This suggests both enhanced adipocyte proliferation and increased lipid accumulation. We further show that there is no significant change in the lipid composition compared to matched SAT. To better delineate the pathophysiology of lipid accumulation, we considered two groups with different genetic backgrounds: (1) lipomas with HMGA2 fusions and (2) without gene fusions. To reduce the search space for genes that are relevant for lipid pathophysiology, we focused on the overlapping differentially expressed (DE) genes between the two groups. Gene Ontology analysis revealed that DE genes are enriched in pathways related to lipid accumulation.ConclusionsWe show that the common shared lipid accumulation mechanism in lipoma is a reduction in lipolysis, with most gene dysregulations leading to a reduced cAMP in the adipocyte. Superficial lipomas could thus be used as a model for lipid accumulation through altered lipolysis as found in obese patients.

Lipoma

This soft-tissue tumor was removed from the thigh. The photograph shows a cross section of a well-delineated, irregularly lobulated, pale yellow lipoma. What is most accurate regarding lipomas?a.Lipomas are usually identified in children and are rare in adultsb.Lipomas frequently have chromosomal aberrationsc.Multiple lipomas are more common than solitary lipomasd.Most lipomas occur in the setting of a genetic syndrome Answer: b. Lipomas frequently have chromosomal aberrations Lipomas are benign, often asymptomatic tumors that are most often identified in adults. Lipomas are usually subcutaneous or superficial, and deep lipomas are less common. Although benign, most lipomas are associated with chromosomal aberrations. Aberrations involving 12q13-15 are common in conventional lipomas and may involve the HMGA2 gene, but other chromosomal aberrations can also occur.1Bartuma H. Hallor K.H. Panagopoulos I. et al.Assessment of the clinical and molecular impact of different cytogenetic subgroups in a series of 272 lipomas with abnormal karyotype.Genes Chromosomes Cancer. 2007; 46: 594-606Crossref PubMed Scopus (66) Google Scholar, 2Gamez J. Playan A. Andreu A.L. et al.Familial multiple symmetric lipomatosis associated with the A8344G mutation of mitochondrial DNA.Neurology. 1998; 51: 258-260Google Scholar Most lipomas are solitary tumors, but multiple lipomas can occur, including in syndromes such as familial multiple lipomatosis.

Cutaneous and Subcutaneous Soft Tissue Tumours in Snakes: A Retrospective Study of 33 Cases

Cutaneous and subcutaneous soft tissue tumours have been rarely described in detail in snakes. Several malignant entities show strikingly similar histological patterns and therefore the term soft tissue sarcoma (STS) has become a standard histopathological diagnosis. The present study characterizes soft tissue tumours in 33 snakes. Samples included 29 surgically excised masses and four carcasses. Additionally, six animals were humanely destroyed and submitted for necropsy examination following tumour recurrence. Benign neoplasms (n=8) were described as lipomas of varying differentiation. Recurrence was observed in two of five snakes in which the clinical course was recorded. Malignant neoplasms (n=25) were diagnosed as STS and graded according to a three-point system previously applied to canine STS. Five (20%) of the primary tumours were classified as grade 1, eleven (44%) as grade 2 and nine (36%) as grade 3 sarcomas. Clinically, recurrence of STS was observed in 11 of 17 cases with available follow-up information. Pathologically, multiple cutaneous metastases were found in one grass snake (Natrix natrix), while visceral metastases were observed in one carpet python (Morelia spilota) and two corn snakes (Pantherophis guttatus). Metastatic risk appears to increase with histological grade. Surgical excision generally represents the current therapy of choice for STS. This study includes the first reports of conventional lipomas in a ribbon snake (Thamnophis radix), angiolipomas in a black-headed python (Aspidites melanocephalus) and a corn snake as well as of STS in a Jamaican boa (Epicrates subflavus), emerald tree boa (Corallus caninus), grass snake (N. natrix), African house snake (Lamprophis fuliginosus), California kingsnake (Lampropeltis getula californiae) and common garter snake (Thamnophis sirtalis).

Vulvar Lipoma-A Rare Case Report

Lipomas are the most common benign tumor of soft tissues. Lipomas are usually soft, fluctuant, painless, subcutaneous lump measuring from 2-20cm diameter. However conventional lipomas have been reported, lipoma of vulva is a rare occurrence and very few cases have been reported in literature. We present a case of vulvar lipoma in 58 year old woman.

Retinoblastoma plus lipomatosis: an autosomal dominant syndrome.

Retinoblastoma plus lipomatosis: an autosomal dominant syndrome.

Rearrangements of chromosome bands 15q12-q21 are secondary to HMGA2 deregulation in conventional lipoma

Rearrangements of chromosome arm 15q are rare but recurrent in conventional lipomas, a tumor type often showing deregulated expression of the HMGA2 gene. In order to assess whether 15q rearrangements could constitute a distinct pathogenetic mechanism, we studied seven cases of conventional lipoma that at G-banding analysis had various rearrangements of 15q12-q21. The breakpoints in 15q were mapped by fluorescence in situ hybridization (FISH) and single nucleotide polymorphism array analyses, and the status of the HMGA2 gene was evaluated by FISH and/or quantitative PCR. We found an overlapping deletion on 15q in two cases, but no recurring breakpoint among the other cases. In addition, all cases displayed rearrangement of HMGA2 at the genomic or the transcriptional level. Although 15q rearrangements sometimes are noted as the sole aberration at cytogenetic analysis of conventional lipomas, they are secondary to HMGA2 deregulation.

Loss of Retinoblastoma Protein Expression in Spindle Cell/Pleomorphic Lipomas and Cytogenetically Related Tumors

Consistent rearrangements of chromosomes 13q and 16q have been identified in spindle cell and pleomorphic lipomas by cytogenetics. Mammary-type myofibroblastoma and cellular angiofibroma show overlapping histologic features and similar chromosomal losses, suggesting a possible relationship among these tumor types. The tumor suppressor gene RB1, encoding the retinoblastoma (Rb) protein, is located at 13q14, within a minimally deleted region in spindle cell lipoma. The purpose of this study was to examine expression of Rb by immunohistochemistry in spindle cell lipoma, pleomorphic lipoma, mammary-type myofibroblastoma, and cellular angiofibroma, and in histologic mimics, to determine its potential diagnostic utility. Whole-tissue sections of 194 tumors were evaluated: 18 spindle cell lipomas, 20 pleomorphic lipomas, 19 mammary-type myofibroblastomas, 16 cellular angiofibromas, 22 conventional lipomas (8 intramuscular), 18 atypical lipomatous tumors (all positive for MDM2 and CDK4), 19 solitary fibrous tumors, 19 myxoid liposarcomas, 14 hibernomas, 11 deep (aggressive) angiomyxomas, 9 angiomyofibroblastomas, and 9 vulval fibroepithelial stromal polyps. Immunohistochemistry was performed after pressure cooker antigen retrieval using a mouse anti-Rb monoclonal antibody. Nuclear staining for Rb was scored as "intact" or "deficient." Rb expression was deficient in all spindle cell lipomas, pleomorphic lipomas, and cellular angiofibromas and in 17 (89%) mammary-type myofibroblastomas. Rb staining was sometimes difficult to interpret in cellular angiofibromas with reactive stromal changes. Rb was also deficient in 2 (9%) conventional lipomas. Rb expression was intact in all other tumor types evaluated. In summary, of the soft tissue tumors associated with 13q deletions, all spindle cell lipomas, pleomorphic lipomas, and cellular angiofibromas and most mammary-type myofibroblastomas show loss of Rb expression. Rb expression is intact in histologic mimics. These findings reinforce the pathogenetic relationship among this group of tumors and demonstrate the potential diagnostic utility of immunohistochemistry for Rb.

Gene expression and single nucleotide polymorphism array analyses of spindle cell lipomas and conventional lipomas with 13q14 deletion

Spindle cell lipomas (SCL) are circumscribed, usually s.c. tumors that typically occur on the posterior neck, shoulder, and back of middle aged men. Cytogenetically, almost all SCL are characterized by deletions of chromosome arm 13q, often in combination with loss of 16q. Deletions of 13q are seen also in approximately 15% of conventional lipomas. Through single nucleotide polymorphism (SNP) array analyses, we identified two minimal deleted regions (MDR) in 13q14 in SCL. In MDR1, four genes were located, including the tumor suppressor gene RB1. MDR1 in SCL overlapped with the MDR detected in conventional lipomas with 13q14 deletion. In MDR2 in SCL there were 34 genes and the two microRNA (miRNA) genes miR-15a and miR-16-1. Global gene expression analysis was used to study the impact of the deletions on genes mapping to the two SCL-associated MDR. Five genes (C13orf1, DHRS12, ATP7B, ALG11, and VPS36) in SCL and one gene (C13orf1) in conventional lipomas with 13q-deletions were found to be significantly underexpressed compared with control tissues. Quantitative real-time PCR showed that miR-16-1 was expressed at lower levels in SCL than in the control samples. No mutations were found at sequencing of RB1, miR-15a, and miR-16-1. Our findings further delineate the target region for the 13q deletion in SCL and conventional lipomas and show that the deletions are associated with down-regulated expression of several genes, notably C13orf1, which was the only gene to be significantly down-regulated in both tumor types.

Sialolipoma of the Parotid Gland

A 33-year-old male patient with a slow-growing, painless, well-circumscribed soft tissue mass on the left parotid region is presented. The clinical impression was that of a benign salivary gland tumor. The tumor was situated in the superficial lobe of the gland, and a superficial parotidectomy was performed, with preservation of the facial nerve. Histopathologic examination results revealed a sialolipoma of the parotid gland and a lesion that consisted of both mature adipose tissue and glandular elements. Sialolipomas share similar clinical features with conventional lipomas of the salivary glands. Preoperative diagnosis is generally difficult, and computed tomographic scanning is useful in defining these benign parotid gland masses. Superficial parotidectomy is the usual surgical treatment for parotid gland superficial lobe lipomas, with near-total absence of recurrence.

Cytogenetic and molecular cytogenetic findings in lipoblastoma

Lipoblastoma is a rare benign tumor that arises from embryonic adipose tissue and usually occurs in young children. Here, we present a review of available cytogenetic data and the karyotypes of 10 new cases of lipoblastoma, of which 7 could be studied further by fluorescence in situ hybridization (FISH) with regard to the involvement of the PLAG1 gene. All seven tumors with clonal aberrations harbored breakpoints in 8q11∼q13, in agreement with literature data. Including previously published cases, 33/40 (82%) lipoblastomas had rearrangement of the 8q11∼q13 region. These rearrangements target the PLAG1 gene, which becomes upregulated through promoter swapping. FISH revealed that five of seven cases in our series had a rearrangement of the PLAG1 gene. Occasionally, there can be difficulties in distinguishing a lipoblastoma from a conventional lipoma or a myxoid liposarcoma. As 8q11∼q13 rearrangements have been reported in only 3% of conventional lipomas and never in myxoid liposarcoma, cytogenetic analysis or FISH for the PLAG1 gene can provide useful differential diagnostic information.

Frequent Detection of Androgen Receptors in Spindle Cell Lipomas: An Explanation for This Lesion's Male Predominance?

Spindle cell lipoma (SCL) is a tumor with marked male predilection. We discovered one SCL that exhibited strong immunoreactivity for androgen receptors (ARs) in the spindle cells. The hypothesis was that ARs in SCLs would not be rare and that all or nearly all SCLs would be AR positive, perhaps explaining its male predominance. Twenty-eight cases of SCL (22 men, 6 women) and a control group of 20 conventional lipomas (10 men, 10 women) were stained with monoclonal AR antibody (1: 150; Dako, Carpinteria, Calif) using the Ventana Discovery. Only nuclear reactivity was considered positive, as noted in prostate controls. Cell types (fat, spindle cells) and extent of staining were recorded as rare, considered negative, focal (1+), or diffuse (2+/3+). All 22 cases of SCL in men were positive for ARs. Twenty showed diffuse (2+/3+) reactivity mainly in the spindle cells. Of the 6 SCLs in women, 1 was AR negative, 1 showed a 3+ reaction in the spindle cells, and 4 had weak (1+) staining of spindle cells. Overall, 96% of SCLs were AR positive, including 83% of SCLs in women. Seventy percent of conventional lipomas showed positive staining in fat, but only 2 showed 2+ staining. In the rest, staining was rare or weak (1+). Nearly all SCLs exhibited AR reactivity. However, the presence of ARs in a substantial percentage of ordinary lipomas and in SCLs in females mitigates against the hypothesis that AR reactivity alone can explain the marked male predominance of SCL.

Large Vulvar Lipoma in an Adolescent: A Case Report

Lipomas are the most common benign tumors of soft tissues. However, conventional lipomas have been reported only rarely as presenting in the vulva. We present a case of vulvar lipoma in a 17-yr-old woman, possibly caused by chronic intermittent irritation.

Assessment of the clinical and molecular impact of different cytogenetic subgroups in a series of 272 lipomas with abnormal karyotype

Conventional lipomas harbor karyotypic changes that could be subdivided into four, usually mutually exclusive, categories: rearrangement, in particular through translocations, of chromosome bands 12q13-15, resulting in deregulation of the HMGA2 gene, loss of material from or rearrangement of chromosome 13, supernumerary ring or giant marker chromosomes, and aberrations of chromosome band 6p21. In the present study, 272 conventional lipomas, two-thirds of them deep-seated, with acquired clonal chromosome changes were assessed with regard to karyotypic and clinical features. A nonrandom distribution of breakpoints and imbalances could be confirmed, with 83% of the cases harboring one or more of the previously known cytogenetic hallmarks. Correlation with clinical features revealed that lipomas with rings/giant markers were larger, occurred in older patients, were more often deep-seated, and seemed to have an increased tendency to recur locally, compared with tumors with other chromosome aberrations. The possible involvement of the HMGA2 gene in cases that did not show any of the characteristic cytogenetic changes was further evaluated by locus-specific metaphase fluorescence in situ hybridization (FISH) and RT-PCR, revealing infrequent cryptic disruption of the gene but abundant expression of full length or truncated transcripts. By FISH, we could also show that breakpoints in bands 10q22-23 do not affect the MYST4 gene, whereas breakpoints in 6p21 or 8q11-12 occasionally target the HMGA1 or PLAG1 genes, respectively, also in conventional lipomas.

A clinicopathological study of lipomas of the head and neck

Background: Lipoma of the head and neck region are fairly common. Methods: This twelve year retrospective study evaluated thirty-nine cases of head and neck lipomas in Nigerians. Results: They constituted 14.4% of benign tumours of the head and neck region and 17.6% of total body lipomas seen within the study period. There were two peaks in the age distribution with patients in the fifth and seventh decades of life recording the highest number of cases. More males were affected with a male-female ratio of 2:1. Most cases (33.3%) were seen in the neck, followed by the scalp (23.1%). Only one intra oral case presenting on the tongue was recorded. The two patients with multiple lipomas were negative for associated systemic disease. Two histological variants were seen (conventional and fibrolipoma). Conclusion: Tumours of adipose tissue are common head and neck neoplasms. While conventional lipomas are the commonest histological variants, the diagnosis of these lesions may be arrived at from clinical presentations supplemented with histological examinations. Treatment by surgical excision (lipectomy) produces satisfactory results. (Nig J Surg Res 2003; 5; 12 – 17) Key words: Head and neck, lipomas