Radiologic-histopathologic correlation of fatty island sign with fat necrosis in atypical lipomatous tumor and lipoma.

AIM: This study aimed to assess the imaging features of atypical lipomatous tumors (ALTs) and lipoma with fat necrosis. METHODS: This study included patients with histopathologically proven fat necrosis within adipocytic tumors who underwent preoperative imaging. Magnetic resonance imaging (MRI) and/or computer tomography (CT) findings of fat necrosis associated with lipomatous tumors were retrospectively reviewed, emphasizing the "fatty island sign (FIS)." FISs were defined as well-demarcated, focal fat-containing areas surrounded by more thickened septa compared with other intratumoral septa. Imaging findings of FIS were compared between ALT and lipoma. RESULTS: Fat necrosis was histopathologically confirmed in 17 patients (6 ALTs and 11 lipomas). Among them, 18 FISs were observed in 10 lesions (59%). Multiple FISs within a lesion were observed in 4 (40%) patients. The median maximum diameter of the FISs was 37 mm. Hypointense areas within FISs relative to the subcutaneous fat on T1- and T2-weighted images were observed in 8 (80%) and 9 (90%), respectively, whereas hyperintense areas within FISs on fat-suppressed T2-weighted images were observed in 2 (20%). Nonfatty solid components within FISs were observed in 2 (20%). On CT, increased fat attenuation and pure fat attenuation within FISs were observed in 6 (86%) and 1 (14%), respectively. The imaging findings of FIS were not significantly different between ALT and lipoma. CONCLUSION: FISs were observed in 59% of the histologically proven ALT and lipoma patients with fat necrosis. The hypointense areas relative to the subcutaneous fat on T1- and T2-weighted images and increased fat attenuation on CT were usually observed within FISs.

Inhibition of Adipocyte Necroptosis Alleviates Fat Necrosis and Fibrosis After Grafting in a Murine Model.

BACKGROUND: Because of the delicate structure of the adipose tissue, fat necrosis accounts for 43.7% of all complications after autologous fat grafting; however, its regulation remains unclear. OBJECTIVES: The purpose of this study was to examine the role of necroptosis in fat graft remodeling after grafting. METHODS: Clinical fat graft necrosis samples were collected, and the expression levels of the necroptosis marker phosphorylated(p)-MLKL were analyzed. Transcriptome analysis was performed on fat grafts before and 1 week after transplantation in C57BL/6 mouse fat grafting models. Additionally, the in vivo effects of RIPK1 inhibitor Nec-1s or RIPK3 inhibitor GSK'872 on the fat grafting complications, including fat necrosis and fibrosis, were investigated. RESULTS: Necroptosis markers were observed and associated with higher occurrence of fibrosis in clinical fat graft necrosis samples compared to normal fat tissue. Amplification and RNA-Seq were conducted on RNA isolated from fat grafts before and after grafting. MLKL, RIPK1, and RIPK3's expression levels were significantly upregulated in comparison to controls. Higher expression levels of necroptotic RNAs were associated with higher levels of DAMPs, including Cxcl2, HMGB1, S100a8, S100a9, Nlrp3, and IL33, and activated proinflammatory signaling pathways, including the TNF, NF-kappa B, and chemokine signaling pathways. Necroptotic inhibitor Nec-1s and GSK'872 robustly suppressed the p-MLKL expression level and significantly inhibited necroptotic cell death, especially in adipocytes. Moreover, administration of Nec-1s and GSK'872 significantly alleviated fat necrosis and subsequent fibrosis in fat grafts. CONCLUSIONS: Collectively, our study findings highlight the potential therapeutic applications of necroptosis inhibitors in preventing fat necrosis and fibrosis after grafting.

Congenital liquified subcutaneous fat necrosis in a newborn: an unusual case.

Subcutaneous fat necrosis of the newborn is a self-limited disorder of the panniculus that arises in the first six weeks of life. Some differential diagnoses may be difficult such as bacterial cellulitis or erysipelas. The prognosis is usually favorable but there are serious complications for which the patient must be regularly monitored, especially hypercalcemia. We report a case of a full-term newborn with a liquidated area of subcutaneous fat necrosis. A surgical incision was performed because of the discomfort and the lack of regression. Hypercalcemia and nephrocalcinosis appeared afterward. A set of clinical, biological, and histological arguments allows the diagnosis of subcutaneous fat necrosis. Follow-up to early detection and to manage such complications is necessary.

Fat necrosis in the breast: a multimodality imaging review of its natural course with different aetiologies.

Fat necrosis of the breast is a commonly encountered condition in daily practice. It is a benign pathology, but it can have variable manifestations and patterns that may sometimes mimic malignancy, depending on its stage of evolution and its underlying cause. This review demonstrates the wide spectrum of appearances of fat necrosis on mammography, digital breast tomosynthesis (DBT), ultrasound, magnetic resonance imaging (MRI), computed tomography (CT), and positron-emission tomography (PET). Sequential follow-up images are included in some cases to illustrate the temporal change of the findings. The typical location and distribution of fat necrosis from a comprehensive list of aetiologies are discussed. Improved knowledge of the multimodality imaging features of fat necrosis could enhance diagnostic accuracy and clinical management, thus avoiding unnecessary invasive investigations.

Rapid cytologic diagnosis of subcutaneous fat necrosis of the newborn.

Subcutaneous fat necrosis of the newborn is a rare self-limited panniculitis that classically presents within the first few weeks of life. The diagnosis is typically clinical, but some cases require skin biopsy with hematoxylin and eosin stain for confirmation. We report a previously undocumented rapid diagnostic protocol that involves collecting a small amount of exudate from a suppurative lesion, placement onto a slide without fixation, and simply viewing the material under a microscope. This novel and practical method of diagnosis reveals doubly refractile crystals diagnostic of subcutaneous fat necrosis without a biopsy, which may be helpful for rapid diagnosis or use in low resource settings.

Natural course of fat necrosis after breast reconstruction: a 10-year follow-up study.

BACKGROUND: Although fat necrosis is a minor postoperative complication after breast reconstruction, occasionally it mimics to tumor recurrence in patients with breast cancer. Therefore, the surgeon should distinguish between benign fat necrosis and true local recurrence. The authors evaluated the clinical characteristics of fat necrosis after breast reconstruction and investigated the natural course of fat necrosis. METHODS: Between 2007 and 2013, a total of 362 patients underwent breast reconstruction after partial or total mastectomy for breast cancer in Kyungpook National University Hospital. Clinicopathologic characteristics and the occurrence of fat necrosis were assessed during surveillance for 10 years of mean follow-up period. RESULTS: There were 42 cases (11.6%) of fat necrosis after breast reconstruction with partial or total mastectomy which were confirmed by needle or excision biopsy. The fat necrosis was resolved after a mean period of 45.9 months (SD, ± 42.1) and 26 cases (61.9%) of fat necrosis were almost completely resolved (less than 5 mm) during 10-year follow-up period. CONCLUSION: Based on the natural course of fat necrosis, the fat necrosis after breast reconstruction can be only monitored, if pathologic confirmation was done. More than half of the cases will be resolved within 2-3 years.

Carboxyl Ester Lipase May Not Mediate Lipotoxic Injury during Severe Acute Pancreatitis.

Acute lipolysis of visceral fat or circulating triglycerides may worsen acute pancreatitis (AP)-associated local and systemic injury. The pancreas expresses pancreatic triacylglycerol lipase (PNLIP), pancreatic lipase-related protein 2 (PNLIPRP2), and carboxyl ester lipase (CEL), which may leak into the visceral fat or systemic circulation during pancreatitis. We, thus, aimed to determine the pancreatic lipase(s) regulating lipotoxicity during AP. For this AP, associated fat necrosis was analyzed using Western blot analysis. Bile acid (using liquid chromatography-tandem mass spectrometry) and fatty acid (using gas chromatography) concentrations were measured in human fat necrosis. The fat necrosis milieu was simulated in vitro using glyceryl trilinoleate because linoleic acid is increased in fat necrosis. Bile acid requirements to effectively hydrolyze glyceryl trilinoleate were studied using exogenous or overexpressed lipases. The renal cell line (HEK 293) was used to study lipotoxic injury. Because dual pancreatic lipase knockouts are lethal, exocrine parotid acini lacking lipases were used to verify the results. PNLIP, PNLIPRP2, and CEL were increased in fat necrosis. Although PNLIP and PNLIPRP2 were equipotent in inducing lipolysis and lipotoxic injury, CEL required bile acid concentrations higher than in human fat necrosis. The high bile acid requirements for effective lipolysis make CEL an unlikely mediator of lipotoxic injury in AP. It remains to be explored whether PNLIP or PNLIPRP2 worsens AP severity in vivo.

Fat necrosis with an associated lymphocytic infiltrate represents a histopathologic clue that distinguishes cellular dermatofibroma from dermatofibrosarcoma protuberans.

BACKGROUND: Cellular dermatofibromas (CDFs) and dermatofibrosarcoma protuberans (DFSP) can be challenging to differentiate from one another. Morphologically, both entities commonly extend into the subcutis, exhibit high cellularity with limited cytologic atypia and have a mixed fascicular-to-storiform growth pattern. We sought to evaluate the significance of fat necrosis with an associated lymphocytic infiltrate as a histopathologic clue for distinguishing CDFs from DFSP. METHODS: We identified cases in our pathology database with a primary diagnosis of CDF or DFSP. Punch or excisional biopsy specimens with extension into the subcutis were selected. Previously biopsied lesions and specimens that did not interact with the subcutis were excluded. Histopathologic features were evaluated in hematoxylin and eosin stained sections. RESULTS: Fat necrosis with lymphocytic infiltrate was present in 20/20 cases of CDF. None of the 20 DFSP cases had fat necrosis with lymphocytic infiltrate although 4/20 had fat necrosis alone. CONCLUSIONS: Fat necrosis with associated lymphocytic response can aid in the distinction between CDF and DFSP.

Ischemic necrosis of the breast following septic shock: A case report.

Fat necrosis of the breast is a common and benign entity, often secondary to trauma, surgery, radiation therapy, or unknown etiologies. Critically ill patients with septic shock may experience end-organ hypoperfusion and tissue infarction and necrosis, which may result in breast fat necrosis, however, to the best of our knowledge this has not been previously described. We report a case of biopsy-proven breast fat necrosis secondary to septic shock following an emergency surgery in a postmenopausal female.

Necrosis grasa subcutánea múltiple: correlación ecográficohistopatológica. Multiple encapsulated fat necrosis: histopathological relation to ultrasound findings.

Encapsulated fat necrosis is a benign entity that has multiple possible conditions in the differential diagnosis. Because of this, the ultrasound and histological studies become highly relevant. We present a 14-year-old boy with this condition who exhibited numerous nodules that were detected after an intentional weight loss of 20kg. The ultrasound and histopathological examinations were necessary to confirm the diagnosis. Even though there is not a clear traumatic record in all cases, trauma constitutes the main hypothesis for its development, by decreasing the blood supply to the adipose tissue lobules and causing subsequent ischemic necrosis. Similar lesions have been described in the omentum and in the breast after surgical procedures or invasive diagnostic tests. In the ultrasound study, at least three presentation patterns have been described, which might match the three histological states, from early fat tissue degeneration to ultimate necrosis and even calcification. It is important to know the clinical characteristics, the ultrasound patterns, and the histological findings of this condition for an accurate diagnosis.

Fat necrosis of the newborn. / Necrosis grasa del recién nacido.

INTRODUCTION: Panniculitis is a group of diseases that affect subcutaneous fat tissue and clinically manifest as nodules. Its pathogenesis is not entirely clear, and it is usually asymptomatic. The confirma tory diagnosis is histological. OBJECTIVE: To describe the clinical and histopathological characteristics of a case of fat necrosis, a specific form of panniculitis in the newborn (NB). CLINICAL CASE: 40-week female NB, born by emergency cesarean section due to fetal tachycardia with meconium, Apgar score 7-8-9. She required oxygen and positive pressure for five minutes. On the fifth day of life, she presen ted an increased volume in the posterior trunk region, with an erythematous - purplish discoloration, which is soft and non-tender to palpation. Skin and soft tissues ultrasound showed increased echo genicity of the subcutaneous cellular tissue and loss of definition of the adipocytes of 42.3 x 9.7 x 20.1 mm approximately, without vascularization. Skin biopsy showed epidermis with irregular acanthosis and basket-weave orthokeratosis; papillary dermis with inflammatory infiltrate, and reticular dermis and adipose tissue with presence of lymphohistiocytic infiltrate with a tendency to form nodules, without vascular involvement, and small cholesterol deposits, compatible with subcutaneous fat ne crosis (SBFN) of the newborn. The patient at three months of age had complete regression of the lesion. CONCLUSIONS: a clinically and histologically compatible case with SBFN is described, that did not present complications during observation. In general, this pathology has a good prognosis, with spontaneous resolution as in our case.

Pancreatic fat necrosis in a 10-year-old girl: A case report and review of the literature.

We report here a case of a young girl with pancreatitis and pancreatic fat necrosis (PFN). This condition is rare in the pediatric age group, and its etiopathogenesis is different from disease in adults. Whereas PFN in adults typically results from pancreatitis secondary to pancreatic duct obstruction, alcohol abuse, and pancreatic adenocarcinoma, in children it appears to arise in a setting of systemic disease, often involving a genetic disorder.

Subcutaneous fat necrosis of the newborn and associated hypercalcemia: A systematic review of the literature.

Subcutaneous fat necrosis of the newborn is an uncommon disorder, and although usually benign, associated hypercalcemia can lead to complications such as failure to thrive and renal failure. Many sources suggest screening for hypercalcemia for 6 months following resolution of skin lesions, but little data are available to support this recommendation. This study examines existing published literature to better guide practitioners regarding screening evaluations of asymptomatic patients with subcutaneous fat necrosis. A systematic review of the literature was conducted using a PubMed English literature search. Data from case reports and case series were collected regarding the presence of hypercalcemia and associated complications, birth history, and age of onset/resolution of skin lesions and laboratory abnormalities. Approximately half (51%) of infants reported had hypercalcemia. Most (77%) developed detectable hypercalcemia within 30 days of skin lesion onset, and 95% developed detectable hypercalcemia within 60 days of skin lesion onset. Hypercalcemia was detected in only 4% of patients > 70 days following onset of skin lesions. Seventy-six percent had resolution of hypercalcemia within 4 weeks of detection. Hypercalcemia was more prevalent in full-term vs pre-term infants (P-value = 0.054), and higher birthweight was significantly associated with an increased risk of developing hypercalcemia (P-value = 0.022). Although gestational age trended toward significance, the only statistically significant clinical feature predicting the development of hypercalcemia was higher birthweight. Current recommendations for laboratory monitoring are not evidence-based, and this study provides interim data to guide practitioners until prospective, randomized controlled trials are conducted.

Subcutaneous fat necrosis, a rare but serious side effect of hypoxic-ischemic encephalopathy and whole-body hypothermia.

Objective To describe the clinical characteristics and risk factors in infants with subcutaneous fat necrosis (SFN) following therapeutic hypothermia for hypoxic-ischemic encephalopathy (HIE). Methods A case-control study was performed by a retrospective chart review of infants with moderate or severe HIE admitted to a level IV regional perinatal center and who underwent whole-body cooling. Results A total of 14 (8.1%) of 171 infants with moderate or severe HIE who underwent whole-body cooling developed SFN during hospitalization. There were more females [71% (10/14)] and large-for-gestational age (LGA) infants [28% (4/14)] in the SFN group vs. 36% females (57/157) and 8% LGA infants (13/157) in the group without SFN (P-values of 0.009 and 0.015, respectively). The mean lowest platelet count was lower 108 ± 55 109/L vs. 146 ± 62 109/L and the mean highest calcium level was higher 11.3 ± 2.5 vs. 10.6 ± 0.8 mg/dL in infants with SFN vs. infants without SFN, respectively (P-values of 0.0078 and 0.006, respectively). Distribution of skin lesions followed distinctive patterns representing the areas with direct contact with the cooling blanket. One infant developed severe, life-threatening hypercalcemia that required aggressive management, including diuretics, corticosteroids and bisphosphonates. Conclusion Although SFN is a rare complication of therapeutic hypothermia, it can be a life-threatening condition if complicated by severe hypercalcemia. Infants who undergo therapeutic hypothermia for HIE need regular skin examinations to evaluate for SFN. If SFN is identified, monitoring of serum calcium levels to prevent life-threatening hypercalcemia is recommended.

Diffuse dermal angiomatosis of the breast with adjacent fat necrosis: a case report and review of the literature.

Diffuse dermal angiomatosis (DDA) is a type of reactive skin angioproliferation. Clinically, this rare disorder presents as red-violet purpuric papules and/or plaques (some with a greater tendency towards necrosis and ulceration), which can be localized in any body area, but is most often seen in the upper and lower extremities. Localization in the breast commonly presents with severe intractable breast pain and characteristic reticular violaceous erythematous plaques with central ulcerations. Histological examination is fundamental for the diagnosis and is characterized by varied patterns of lobular or diffuse hyperplasia of endothelial cells at the extravascular level. The condition is associated with various underlying conditions, many of which result in local tissue ischemia. In this report, we present a patient with DDA with an underlying mass lesion of the breast, which proved to be an adjacent fat necrosis. Various treatments have proven beneficial, including revascularization, oral corticosteroids, smoking cessation, and isotretinoin. In this case, our patient benefited from secondary excision of the affected area.

Cutaneous complication of perinatal hypoxia.

Subcutaneous fat necrosis of the newborn is an uncommon, transient, and self-healing panniculitis, mostly affecting term newborns with perinatal complications. The authors present a case of a female full-term neonate, born from an uncomplicated pregnancy, admitted into the neonatology unit 5 hours after delivery because of refractory multifocal seizures in the context of hypoxic-ischemic encephalopathy. Nine days after birth, indurated and erythematous nodules and plaques were noted on the left arm and back. Skin biopsy was compatible with subcutaneous fat necrosis of the newborn. Laboratory evaluation including serum calcium showed normal values. No treatment was initiated. This entity generally follows an uncomplicated course. However, there are important complications for which the patient must be regularly monitored, including thrombocytopenia, hypoglycemia, hypertriglyceridemia, and most importantly, hypercalcemia. Patients should have serial serum calcium determinations for up to 6 months after the appearance of the skin lesions. The early diagnosis and prompt treatment of hypercalcemia are essential to prevent severe complications.

Pseudomembranous changes in the dermis: A novel observation and potential clue for evolving lipodermatosclerosis?

Lipodermatosclerosis (LDS) is a well-recognized form of fibrosing panniculitis. Although chronic cases are readily diagnosed, early and evolving lesions may be clinically mistaken for cellulitis and other forms of panniculitis. Most pathologists are familiar with a pseudomembranous type of fat necrosis as a useful feature of chronic LDS. Although nonspecific, this distinctive pattern of fat necrosis helps in supporting a diagnosis of LDS in the appropriate clinical context. The histopathologic features of early and evolving LDS and those involving the dermis are less well documented. We report a case of early LDS showing extensive pseudomembranous changes in the dermis on a superficial skin biopsy where progression to a classic established lesion was documented clinically. We suspect that this previously unreported and unusual finding may be a histopathologic clue for evolving lesions of LDS.

Neutrophil-rich subcutaneous fat necrosis of the newborn: A potential mimic of infection.

BACKGROUND: The inflammatory infiltrate seen in biopsy specimens obtained from patients with subcutaneous fat necrosis of the newborn (SCFN) has classically been described as consisting mostly of histiocytes. However, we encountered patients with SCFN whose biopsy specimens revealed mostly neutrophils, prompting infection to be an initial consideration. OBJECTIVES: We sought to describe cases of SCFN in which neutrophils formed the majority of the infiltrate at our institution and in the literature. METHODS: We performed a retrospective analysis of patients with SCFN reported at our institution and a literature review of SCFN. RESULTS: Thirteen cases of SCFN were identified at our institution. In 2 of 13 cases, neutrophils composed >75% of the inflammatory infiltrate, and both lesions were 1 day old. From the literature review, neutrophils were mentioned as a component of the infiltrate in 10 of 124 cases, but in none were neutrophils described as forming the majority of the infiltrate. LIMITATIONS: This study is limited by its retrospective nature and small sample size. CONCLUSIONS: Neutrophils can comprise most of the inflammatory cells in patients with SCFN, especially early in the course of the disease. This variant of SCFN can be easily mistaken for infection.

An Extraordinary Manifestation of Nodular Cystic Fat Necrosis.

Nodular cystic fat necrosis (NCFN) is characterized by mobile subcutaneous nodules composed of necrotic adipocytes encapsulated by fibrous tissue. The classical presentation of NCFN is solitary or multiple, up to 40, discrete nodules scattered usually on the extremities or trunk. Here, the authors present an elderly woman who developed an unusual and striking clinical picture of NCFN, two months after a fall. The patient had a large indurated plaque and subcutaneous nodule with superposing necrotic ulcers. During debridement of the ulcers, nearly 100 small nodules popped up freely along with a brownish discharge. Deep in the ulcer, the authors discovered a dislocated nail that belongs to an old hip prosthesis. Histopathological findings of the nodules were compatible with NCFN.