Lipomatoses

Lipomatoses are benign proliferation of adipose tissue. Lipomas (benign fat tumors) are the most common component of lipomatosis. They may be unique or multiple, encapsulated or not, subcutaneous or sometimes visceral. In some cases, they form large areas of non-encapsulated fat hypertrophy, with a variable degree of fibrosis. They can develop despite the absence of obesity. They may be familial or acquired. At difference with lipodystrophy syndromes, they are not associated with lipoatrophy areas, except in some rare cases such as type 2 familial partial lipodystrophy syndromes (FPLD2). Their metabolic impact is variable in part depending on associated obesity. They may have functional or aesthetic consequences. Lipomatosis may be isolated, be part of a syndrome, or may be visceral. Isolated lipomatoses include multiple symmetrical lipomatosis (Madelung disease or Launois-Bensaude syndrome), familial multiple lipomatosis, the painful Dercum's disease also called Adiposis Dolorosa or Ander syndrome, mesosomatic lipomatosis also called Roch-Leri lipomatosis, familial angiolipomatosis, lipedema and hibernomas. Syndromic lipomatoses include PIK3CA-related disorders, Cowden/PTEN hamartomas-tumor syndrome, some lipodystrophy syndromes, and mitochondrial diseases, especially MERRF, multiple endocrine neoplasia type 1, neurofibromatosis type 1, Wilson disease, Pai or Haberland syndromes. Finally, visceral lipomatoses have been reported in numerous organs and sites: pancreatic, adrenal, abdominal, epidural, mediastinal, epicardial… The aim of this review is to present the main types of lipomatosis and their physiopathological component, when it is known.

Epiploic appendagitis of the vermiform appendix--An unusual mimic of acute appendicitis

Epiploic appendagitis is a condition resulting from ischemia or necrosis involving the appendage epiploica either due to torsion or spontaneous thrombosis of the venous outflow. It is one of the myriad causes of acute abdominal pain and can masquerade clinically as appendicitis, omental infarction, sclerosing mesenteritis and even diverticulitis. Epiploic appendagitis of the vermiform appendix is a rare entity, clinically indistinguishable from appendicitis. We present a 45-year-old male patient with 4-day duration of right iliac fossa pain and tenderness, with strong clinical suspicion of acute appendicitis. CT scan of the abdomen and pelvis demonstrated Epiploic appendagitis of the vermiform appendix, whilst the appendix remained uninflamed. The patient was thus discharged with conservative management without having to go undergo needless surgery, thereby avoiding the potential complications thereof.

Epiploic appendagitis: pathogenesis, clinical findings and imaging clues of a misdiagnosed mimicker

Primary epiploic appendagitis (PEA) is a rare and frequently underdiagnosed cause of acute abdominal pain. PEA most commonly affects obese, male patients in the 4th and 5th decade of life. Clinical presentation includes acute, localized, non-migrating pain without fever, nausea, vomiting or diarrhea and the laboratory workup is usually within normal limits. PEA is commonly mistaken as other more severe causes of acute abdominal pain, such as diverticulitis, acute appendicitis or cholecystitis and thus patients undergo unnecessary diagnostic and therapeutic procedures. The emergence of computerized tomography (CT) as the gold standard imaging test in diagnostic dilemmas of acute abdominal pain has resulted in increased recognition and diagnosis of PEA. Upon confirmation, PEA is considered a self-limiting disease and is managed conservatively with analgesics, occasionally combined with nonsteroidal anti-inflammatory drugs (NSAIDS). Persistence of symptoms or recurrence mandate the consideration of surgical management with laparoscopic appendage excision as the definitive treatment. We review the current literature of PEA, with a focus on clinical and imaging findings, in order to raise awareness about this frequently misdiagnosed entity.

Paracaval lipoma: Case study and literature review

Paracaval lipoma refers to a fatty tissue collection surrounding the intrahepatic portion of the inferior vena cava (IVC). It is a relatively infrequent benign finding on abdominal CT imaging, speculated to be a result of negative thoracic pressure on the IVC during inspiration. If not recognized, paracaval lipoma can be confused for thrombus or, worse yet, malignant invasion of the IVC, resulting in a costly and unnecessary workup. Here we describe a 51-year-old white male presenting to our institution with a 2-week history of abdominal pain, increasing abdominal girth, jaundice, and ascites; subsequent CT of the abdomen and pelvis without contrast revealed an incidental finding of fat deposition around the caudate lobe with a juxtacaval distribution, consistent with paracaval lipoma.

CT imaging findings of epiploic appendagitis: an unusual cause of abdominal pain

Epiploic appendagitis is a rare cause of acute abdominal pain, determined by a benign self-limiting inflammation of the epiploic appendages. It may manifest with heterogeneous clinical presentations, mimicking other more severe entities responsible of acute abdominal pain, such as acute diverticulitis or appendicitis. Given its importance as clinical mimicker, imaging plays a crucial role to avoid inaccurate diagnosis that may lead to unnecessary hospitalization, antibiotic therapy, and surgery. CT represents the gold standard technique for the evaluation of patients with indeterminate acute abdominal pain. Imaging findings include the presence of an oval lesion with fat-attenuation surrounded by a thin hyperdense rim on CT (“hyperattenuating ring sign”) abutting anteriorly the large bowel, usually associated with inflammation of the adjacent mesentery. A central high-attenuation focus within the fatty lesion (“central dot sign”) can sometimes be observed and is indicative of a central thrombosed vein within the inflamed epiploic appendage. Rarely, epiploic appendagitis may be located within a hernia sac or attached to the vermiform appendix. Chronically infarcted epiploic appendage may detach, appearing as an intraperitoneal loose calcified body in the abdominal cavity. In this review, we aim to provide an overview of the clinical presentation and key imaging features that may help the radiologist to make an accurate diagnosis and guide the clinical management of those patients.

Epiploic appendagitis: A rare cause of acute abdomen

Epiploic appendagitis is a rare cause of acute abdomen that often manifests with acute onset of pain in the left or right lower quadrant. Its symptoms can mimic and be mistaken for acute diverticulitis, appendicitis, or omental infarction. In this case report, we discuss a 65-year-old woman who presented with sharp right upper and lower quadrant abdominal pain, for which she had an emergent abdominal computed tomography (CT) scan. On CT images, epiploic appendagitis will appear as oval lesions with a central area of fat attenuation, accompanied by surrounding inflammation. Ultrasound and magnetic resonance imaging are more often used to evaluate acute abdominal pain in the pediatric and obstetric populations, so the respective findings of acute epiploic appendagitis must be recognized in those examinations as well. Despite the rarity of the condition and its common omission from differential diagnoses, the ability to recognize and diagnose epiploic appendagitis from its imaging is important for radiologists, especially considering its potential complications. If not diagnosed correctly, epiploic appendagitis can result in unnecessary hospital admission and patient workup, antibiotic use, dietary restrictions, and perhaps even unnecessary surgery. In this case, the diagnosis of epiploic appendagitis using CT allowed the patient to avoid surgery and other invasive treatment, and the patient was eventually discharged on conservative medical management.

Correlation between obesity and fat-infiltrated axillary lymph nodes visualized on mammography

OBJECTIVE

Using screening mammography, this study investigated the association between obesity and axillary lymph node (LN) size and morphology.

METHODS

We conducted a retrospective review of 188 females who underwent screening mammography at an academic medical centre. Length and width of the LN and hilum were measured in the largest, mammographically visible axillary node. The hilo-cortical ratio (HCR) was calculated as the hilar width divided by the cortical width. Measurements were performed by a board certified breast radiologist and a resident radiology physician. Inter-rater agreement was assessed with Pearson correlation coefficient. We performed multivariable regression analysis for associations of LN measurements with body mass index (BMI), breast density and age.

RESULTS

There was a strong association between BMI and LN dimensions, hilum dimensions and HCR (p < 0.001 for all metrics). There was no significant change in cortex width with increasing BMI (p = 0.15). Increases in LN length and width were found with increasing BMI [0.6 mm increase in length per unit BMI, 95% CI (0.4-0.8), p < 0.001 and0.3 mm increase in width per unit BMI, 95% CI(0.2-0.4), p < 0.001, respectively]. Inter-rater reliability for lymph node and hilum measurements was 0.57-0.72.

CONCLUSION

We found a highly significant association between increasing BMI and axillary LN dimensions independent of age and breast density with strong interobserver agreement. The increase in LN size was driven by expansion of the LN hilum secondary to fat infiltration. Advances in knowledge: This preliminary work determined a relationship between fat infiltrated axillary lymph nodes and obesity.

Intra-abdominal fat. Part I. The images of the adipose tissue localized beyond organs

Unaltered fat is a permanent component of the abdominal cavity, even in slim individuals. Visceral adiposity is one of the important factors contributing to diabetes, cardiovascular diseases and certain neoplasms. Moreover, the adipose tissue is an important endocrine and immune organ of complex function both when normal and pathological. Its role in plastic surgery, reconstruction and transplantology is a separate issue. The adipose tissue has recently drawn the attention of research institutes owing to being a rich source of stem cells. This review, however, does not include these issues. The identification of fat is relatively easy using computed tomography and magnetic resonance imaging. It can be more difficult in an ultrasound examination for several reasons. The aim of this paper is to present various problems associated with US imaging of unaltered intra-abdominal fat located beyond organs. Based on the literature and experience, it has been demonstrated that the adipose tissue in the abdominal cavity has variable echogenicity, which primarily depends on the amount of extracellular fluid and the number of connective tissue septa, i.e. elements that potentiate the number of areas that reflect and scatter ultrasonic waves. The normal adipose tissue presents itself on a broad gray scale: from a hyperechoic area, through numerous structures of lower reflection intensity, to nearly anechoic regions mimicking the presence of pathological fluid collections. The features that facilitate proper identification of this tissue are: sharp margins, homogeneous structure, high compressibility under transducer pressure, no signs of infiltration of the surrounding structures and no signs of vascularization when examined with the color and power Doppler. The accumulation of fat tissue in the abdominal cavity can be generalized, regional or focal. The identification of the adipose tissue in the abdominal cavity using ultrasonography is not always easy. When in doubt, the diagnostic process should be extended to include computed tomography or magnetic resonance imaging, or sometimes biopsy (preferably the core-needle one).