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Background: Lipomatous tumors represent the most common type of soft tissue neoplasms. Mouse double minute 2 homolog (MDM2)/cyclin-dependent kinase 4 (CDK4) immunostaining is considered effective in differentiating between benign lipomas and intermediate malignant atypical lipomatous tumors/well-differentiated liposarcomas (ALT/WDLPSs). However, these tumors have traditionally been diagnosed histopathologically using hematoxylin and eosin-stained specimens, which is referred to here as morphological diagnosis. In this study, the accuracy of morphological diagnoses that had been made before MDM2/CDK4 immunostaining became available for distinguishing between lipoma and ALT/WDLPS was examined., Methods: The study participants were 109 patients with a morphological diagnosis of lipoma (68 patients) or ALT/WDLPS (41 patients) who had undergone surgical resection of the tumor in our hospital between 2009 and 2012. Tissue samples from all patients were used for MDM2/CDK4 immunostaining and the confirmation of MDM2/CDK4 amplification by fluorescence in situ hybridization (FISH)., Results: Of the 41 patients with a morphological diagnosis of ALT/WDLPS, only 17 were positive for MDM2 FISH. In addition, one of the 68 patients with a morphological diagnosis of lipoma showed MDM2 amplification by FISH. When the definitive diagnosis of ALT/WDLPS was made by the positive results of MDM2 FISH, the sensitivity and specificity of morphological diagnosis were 41.5% and 98.5%, respectively. The sensitivity of MDM2 and CDK4 immunostaining was 55.6% and 40.0%, respectively, and their specificity was 87.0% and 84.6%, respectively. This indicates that the diagnostic accuracy of these immunostaining assays was not particularly high. The clinical features suggesting ALT/WDLPS were: patient age (older), maximum tumor diameter (large, cut-off value of 125 mm), tumor location (lower limb), and tumor depth (deep-seated)., Conclusions: Morphological diagnosis alone can accurately diagnose lipomas. However, it has a propensity to overdiagnose ALT/WDLPS. Thus, MDM2 FISH should be used more proactively, not only for lesions with obvious morphological abnormalities, but also for lipomatous tumors that are clinically suggestive of ALT/WDLPS., Competing Interests: Declarations. Ethics approval and consent to participate: This study was approved by the Clinical Research Ethics Committee of Nagasaki University Hospital (Approval Number: 17061909–3). Written informed consent was waived by this committee for this retrospective analysis of routinely acquired imaging and clinical data. The outline of this research was published on the homepage of the Clinical Research Center of Nagasaki University Hospital. This guaranteed the patients and any other individuals the opportunity to refuse participation in the study. We did not receive any refusion of participation. Each author certifies that all investigations were conducted in conformity with the ethical principles of research. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Lipomas of the talus are rare benign bone lesions. They are usually atraumatic in aetiology with a male preponderance and generally occur between the third and sixth decades of life. We report the case of a man in his 30s who had presented with pain and swelling in the posteromedial aspect of his left ankle of 6 months' duration, associated with functional restrictions, and was diagnosed as a case of intraosseous lipoma involving the talus. The patient was managed surgically by extended curettage and iliac crest bone grafting. After a period of 1 year, he was able to perform all activities and no recurrence was observed., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Soft tissue lesions are among the most prevalent forms of tumors or tumor-like alterations within the oral cavity. They exhibit a wide spectrum of characteristics, ranging from benign, noninvasive lesions to malignant tumors, which collectively present a diagnostic challenge. A 67-year-old patient presented with an incidental finding of induration on the right cheek during dental hygiene. The intraoral examination revealed a soft, non-tender swelling measuring 20 mm in diameter. The sensitivity and percussion tests for the teeth in the fourth quadrant yielded unremarkable results. Panoramic radiography (OPG) revealed tip-ping of the premolars and an unclear apical finding in region 44. Cone-beam computed tomography (CBCT) revealed a sharply defined, lobulated hypodense lesion in the right buccal area. To clarify the diagnosis and optimize perioperative management, a 3 Tesla dental magnetic resonance imaging (MRI) scan was performed. This identified a 23×6×23 mm lipoma along the right mandibular ramus, causing detachment of the buccinator and de-pressor anguli oris muscles. A cinematic rendering reconstruction derived from the MRI data facilitated enhanced visualization for preoperative planning. The surgical excision was performed under local anesthesia, resulting in the successful removal of the neoplasm while preserving the mental nerve and submandibular gland. Histo-pathology confirmed the presence of a lobulated mature cell lipoma. The patient exhibited no complications during the removal of the sutures, with complete wound healing and no recurrence observed. This article highlights the efficacy of advanced MRI diagnostics and post-processing techniques in the management of ambiguous soft tissue neoplasms., (Copyright 2024 Adib Al-Haj Husain, Esra Salzer, Bernd Stadlinger. License: This work is licensed under a Creative Commons Attribution 4.0 International License.)

Background: Cardiac lipoma, a seldom-encountered benign tumor positioned beneath the endocardium, has the potential to impair electrophysiological functions. Diagnosis is principally based on imaging modalities. The uniqueness of this case lies in the tumor's extension both internally and externally within the right atrium, rendering it of special interest. From a clinical standpoint, surgical removal is commonly advocated, wherein early intervention is pivotal in improving patients' long-term prognoses., Case Presentation: A 35-year-old male was admitted to the hospital for treatment subsequent to the identification of a cardiac mass two days prior. Initial diagnostic assessments, encompassing CT scans and echocardiography, identified a space-occupying lesion within the heart. The patient underwent surgical excision of the cardiac tumor, utilizing mild hypothermic extracorporeal circulation via femoral vessel access. Intraoperative findings revealed adipose-like tissue of a "dumbbell-shaped" configuration situated both within and external to the right atrium, measuring approximately 8 cm*9 cm internally and 7 cm*6 cm externally, with the extracardiac mass being marginally larger. Postoperative pathological analysis confirmed a cardiac lipoma diagnosis. A follow-up echocardiogram conducted three months post-surgery exhibited no notable abnormalities. The patient is under continuous observation to monitor for any recurrence or potential long-term complications., Conclusion: In this case report, we detail with precision a rare cardiac pathology manifested by an expansive infiltrative lipoma that pervades the endocardial and epicardial layers of the right atrium. After thorough preoperative diagnostic workup and evaluation, we contend that surgical intervention represents the optimal therapeutic approach for managing such conditions, with the goal of preemptively reducing the likelihood of cardiac compression or intracardiac obstruction., (© 2024. The Author(s).)

Lipomas are the most prevalent benign soft-tissue tumours, however, pedunculated fibrolipoma in the buttock is rare. Here, the case of a Chinese male patient in his early 70s with a 50-year history of a growing pedunculated fibrolipoma on his right buttock is presented. The attending physician and the registered nurse collaborated on a treatment plan, leading to a successful resection with rhomboid flap transfer. The operation went smoothly, and with continued home care and follow-ups, the patient recovered well, without complications. At 4 months post-surgery, the incision had healed perfectly, boosting the patient's psychological state and allowing him to resume his daily activities unhindered., Competing Interests: Declaration of conflicting interestThe authors declare that there is no conflict of interest.

We present our single-centre experience of two cases of lipochoristoma, a rare lesion causing unilateral hearing loss. Differential diagnoses include the more common vestibular schwannoma, haemangioma and meningioma. Diagnosis was confirmed with fat suppression sequences on MRI. Management of both patients was with serial imaging, under the guidance of neuro-otology multidisciplinary team, due to the slow and typically non-aggressive progression of this lesion., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Colonic lipomas (CLs) are benign tumors of the adipose tissue of the gastrointestinal tract that are often asymptomatic. A search of medical literature in English using PubMed and Google Scholar was conducted for articles related to CL. Occasionally, patients present with intestinal bleeding or obstructive symptoms. Although intussusception is commonly observed in children, it is rare in adults. Moreover, CL as the most common entity, is very rare, with an incidence rate of 0.035% to 4.4%. Although fatty composition can assist in diagnosis through computed tomography and magnetic resonance imaging, the latter cannot exclude local infiltration. CLs are distributed evenly between both sexes and can be located anywhere in the gastrointestinal tract; however, they are more frequently located in the colon, particularly in the right colon and cecum (39.6%), followed by the transverse colon (25%), descending colon (20.8%), and the sigmoid colon (14.6%). Symptoms included abdominal pain (79.2%), alterations in bowel habits (45.8%), rectal bleeding (22.9%), colocolic intussusception (50%), weight loss (6.2%), vomiting (14.6%), and nausea (12.5%). Surgical and endoscopic techniques are widely used to manage CLs. The challenge for physicians is differentiating this lesion from malignant colonic lesions, at the outset. The risk of misdiagnosis is possible, and the recommendation in cases of doubt is still segmental surgical resection, as it ensures correct collection of lymph nodes for appropriate staging of presumed colonic carcinoma., Competing Interests: The authors have no funding and conflicts of interest to disclose., (Copyright © 2024 the Author(s). Published by Wolters Kluwer Health, Inc.)

A rare instance of extravascular lipomas located over the subclavian vein in a woman in her early 60s presented unique diagnostic and therapeutic challenges due to their close proximity to critical structures. Lipomas, which are the most commonly occurring benign soft tissue tumours, are typically composed of mature adipocytes. Although lipomas can develop in any region of the body, they are most commonly found in the subcutaneous tissues of the trunk and proximal limbs. Extravascular lipomas, especially those near major blood vessels like the subclavian vein, are extremely uncommon.In this particular case, the tumour was extensively in contact with the right subclavian vein, though there was no intravascular involvement. The lipomatous tumour was successfully excised during surgery, with the subclavian vein and surrounding structures being preserved. Histopathological analysis confirmed the diagnosis of a benign lipoma. This case highlights the significance of early diagnosis, meticulous surgical planning and multidisciplinary collaboration to achieve the best possible outcomes., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Spindle cell lipoma is a very rare occurrence in the larynx and can be cured by complete excision. In this case report we present the case of a 71-year-old female who presented to the otorhinolaryngology outpatient department of Northwest General Hospital and Research Centre, Peshawar, with complaints of occasional irritation and a foreign body sensation in the throat while swallowing, for the last three years. She had undergone a surgical procedure 30 years back for the same complaint and remained asymptomatic till three years back. On examination, through fibre-optic laryngoscope, the attending surgeon saw an abnormal mass arising from the aryepiglottic folds of the larynx. An excisional biopsy was performed through micro-laryngoscopy. The patient's symptoms subsequently improved and she is currently doing well. Histopathological reports confirmed it as spindle cell lipoma.

Lipomas of the palatine tonsil are rare benign neoplasms in clinical practice. We present a case of palatine tonsillar fibroangiolipoma in a 50-year-old Chinese male with a history of multiple lipomas on the back and extremities. It was diagnosed based on histological examination and integrated analysis. Good wound healing and no evidence of recurrence were noted within 6 months follow-up after tonsillectomy. This article also puts a spotlight on the differential diagnosis of benign tonsillar tumors and reviewed recent relevant literature., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Abstract: Lipomatous hypertrophy of the interatrial septum (LHIS) is a rare but benign cardiac tumor that can be found on cardiac imaging such as echocardiogram, or during surgery or an autopsy. Cardiac MRI is the best imaging modality to determine the borders of the tumor and its extension into the intraventricular septum and ventricular free wall. Patients require close monitoring because LHIS may cause right or left outflow tract obstruction or superior vena cava obstruction, requiring cardiac surgical intervention. This article describes a patient with LHIS who underwent cardiac surgery because of her increasing symptomatology., (Copyright © 2024 American Academy of Physician Associates.)

The entity commonly referred to as chondrolipoma is a rare and enigmatic breast lesion with unclear histogenesis and a complete lack of molecular characterization. It is uncertain whether it represents a hamartoma, choristoma, or a distinct neoplasm, including possibly a variant of mammary-type myofibroblastoma. We report two additional chondrolipomatous lesions of the breast. The lesions had varying histologic and immunohistochemical features similar to myofibroblastoma, including the loss of retinoblastoma (Rb) protein expression in one lesion. Molecular analysis by chromosomal microarray analysis performed on a second lesion did not demonstrate a loss of 13q14 or 16q typical of myofibroblastoma. Our findings further support the concept that at least a subset of breast lesions that historically have been classified as chondrolipoma are related to myofibroblastoma. However, the lack of myofibroblastoma-specific molecular alterations in one lesion suggests chondrolipomas may also have varying origins., Competing Interests: Declaration of Conflicting InterestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Hibernoma is a relatively uncommon benign neoplasm of brown adipose tissue which usually affects head and neck region, thigh and rarely breast. There are different subtypes of hibernoma with the spindle cell-type is the least common one. Herein, we are reporting a case of this rare spindle cell hibernoma in a location which has not been previously reported: perinephric adipose tissue. This tumor was presented as a renal mass on imaging.

Intussusception is rare in adults, making it a challenging and often delayed diagnosis. Patients may re-present with non-specific and subacute abdominal symptoms. Abdominal CT is the most sensitive imaging modality and is often required to make the diagnosis of intussusception. In contrast to the paediatric population, intussusception in adults is most often associated with a pathological lesion acting as a lead point. In adults, the lead point is often secondary to malignancy, though benign lesions can also be implicated. As such, surgical management with selective resection is the mainstay of treatment in adults. We describe a rare case of ileocaecal intussusception in an adult secondary to a large ileocaecal lipoma, successfully treated with laparotomy and resection in a remote Western Australian hospital. The increasing availability of CT imaging and skilled general surgeons in rural and remote Australia allows for the diagnosis and surgical management of such cases without inter-hospital transfer., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Pseudoangiomatous spindle cell lipoma is a rare pattern within the spindle cell lipoma spectrum that exhibits a remarkable histological pattern characterized by its resemblance to vascular lesions, creating a pseudoangiomatous appearance. Approximately 20 to 30 reports have been described in the literature. In this context, we present an intriguing report of pseudoangiomatous spindle cell lipoma showcasing a unique low-fat pseudo angiomatous pattern in a 61-year-old male patient presented with a 6-cm subcutaneous mass on his right arm, which was thoroughly investigated and subsequently excised. Microscopic examination revealed bland spindle cells infiltrates within a fibromyxoid stroma. Notably, the tumor exhibited distinctive branching and dilated vascular-like spaces that formed pseudopapillary (villiform) projections. Interestingly, the tumor displayed certain regions featuring mature adipose tissue components, alongside hyalinized blood vessels. No necrosis, atypical spindle cells, increased mitotic activity, or pleomorphic lipoblasts were observed. The immunohistochemical evaluation demonstrated diffuse positive staining for CD34 and negative staining for STAT6. This report of a low-fat pattern of pseudoangiomatous spindle cell lipoma underscores the importance of recognizing and characterizing rare entity subtype for accurate diagnosis and appropriate management. This report contributes to the expanding understanding of the diverse presentations of pseudo angiomatous spindle cell lipomas and underscores the significance of comprehensive histopathological assessment., Competing Interests: Declaration of Conflicting InterestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Background: Documentation of lingual tumors is scarce in nonhuman primates., Methods: Through a multi-institutional retrospective study we compile cases of primary and metastatic neoplasia in non-human primates., Results: We describe five cases of lingual neoplasia. Three cases are primary lingual tumors: chondro-osteoblastic lipoma in a howler monkey, squamous cell carcinoma, and fibroma in two baboons. We describe two cases of metastatic lymphoma in the tongue in rhesus macaques. A literature review of published lingual neoplasia in nonhuman primates is included in this manuscript., Conclusion: Lingual neoplasia is seldom reported in non-human primates., (© 2024 The Author(s). Journal of Medical Primatology published by John Wiley & Sons Ltd.)

Background: Fibrolipoma of the lower lip is an uncommon condition with limited documentation in the literature. This paper provides updated insights into oral and maxillofacial lipomas through a detailed case report and comprehensive literature review, discussing clinical features, pathogenesis, diagnostic approaches, histopathology, and therapeutic strategies., Case Presentation: A 54-year-old female presented with a painless, enlarging mass on the inner aspect of her right lower lip, first noticed 2 years prior. The mass, now the size of a peanut, interfered with her eating and speech. Physical examination revealed a 2.0 × 2.5 × 1.0 cm mass beneath the mucous membrane of the right lower lip. It was firm, well-demarcated, and mobile. Surgical excision was performed, and histopathological analysis confirmed the diagnosis of a lower lip fibrolipoma. The lesion was successfully removed without recurrence., Conclusion: Lipomas in the oral and maxillofacial regions are rare, slow-growing benign tumors, particularly within the lips. Although their diagnosis is straightforward based on clinical presentation, histopathological confirmation is essential. Surgical resection remains the treatment of choice, with excellent prognostic outcomes., Competing Interests: The authors have no funding and conflicts of interest to disclose., (Copyright © 2024 the Author(s). Published by Wolters Kluwer Health, Inc.)

We describe the presentation and treatment of the first reported case of a nasopharyngeal pleomorphic lipoma. The mass was successfully treated with a combined endoscopic trans-oral surgical excision approach by using low temperature-controlled plasma technology, resulting in optimal patient outcomes. Laryngoscope, 134:2710-2712, 2024., (© 2023 The American Laryngological, Rhinological and Otological Society, Inc.)

Intraneural lipomas and lipofibromas (also called lipofibromatous hamartomas) are rare, benign tumours occurring in peripheral nerves in the forearm and wrist. They usually present as asymptomatic masses, but if they are large enough, they may cause symptoms of compression neuropathy. Intraneural lipomas and lipofibromas differ with regard to anatomy and clinical behaviour: the former tumour has a well-defined capsule and most commonly occurs within the median nerve in the forearm and wrist. It is diagnosed in the fourth and fifth decades of life and seen more frequently in women. The latter (lipofibroma) has no capsule, is infiltrative in nature, is composed of fatty and fibrous tissue and also most commonly seen in the median nerve. It occurs in a younger age group with no sexual predominance. Due to these differences, these lesions are managed differently 1 2., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Parosteal lipomas and osteochondromas of the head and neck are uncommon benign tumors, constituting a small fraction of lipoma and bone tumor cases. We present a unique case of a 66-year-old male with a parosteal lipoma overlying an osteochondroma in the anterior midline neck, causing dysphagia. Surgical excision confirmed the diagnosis, and a literature review revealed similar cases predominantly adjacent to the mandible or calvaria. This case emphasizes the need to have parosteal lipoma and osteochondroma on the differential diagnosis for patients presenting with a firm mass of the central neck, especially with a history of trauma. Laryngoscope, 134:2844-2847, 2024., (© 2023 The American Laryngological, Rhinological and Otological Society, Inc.)

Tumours of adipose tissue origin are relatively rare in the head and neck. Here, we report a case of an unfamiliar lipomatous lesion that involved the neck and mediastinum. A nil-comorbid man in his 40s presented with a slowly progressive anterior neck swelling of 3 years, which was diagnosed as lipoma by histopathological sampling. Computed tomography demonstrated the lesion to be involving parapharyngeal and retropharyngeal spaces with mediastinal extension. The lesion was removed by the transcervical approach. The final histology of the excised specimen, with immunohistochemistry for mouse double minute 2 (MDM2) and p16, suggested an atypical lipomatous tumour (ALT). This report accentuates the occurrence of this rare neoplasm in the neck, which often mimics lipoma clinically. Although radiology can demonstrate suggestive features, histology with MDM2 and/or p16 positivity can confirm the diagnosis of ALT as against the lipoma. A successful transcervical excision, despite the deeper extension of the lesion between the critical structures of the neck and mediastinum, demonstrates the non-infiltrating nature of the tumour., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

This retrospective study aims to examine the characteristics and treatment approaches of colon lipomas, which are benign tumors found in the colon. We analyzed a cohort of 25 patients, focusing on demographic characteristics, clinical presentation, location and size of the lipoma, concomitant pathologies, and treatment methods. The average age of the patients was 67.3 years, with 36% being male and 64% female. The majority of lipomas were located in the ascending colon (52%), and their median size was 2 cm. The predominant presenting symptom was constipation, affecting 83.3% of the symptomatic patients. Surgical resection was undertaken in only 1 patient due to obstruction. Statistically significant differences were observed between symptomatic and asymptomatic patients regarding various parameters, including the size of the lipoma (P = .033). Colon lipomas are generally benign and frequently asymptomatic but may necessitate different treatment approaches depending on their size, location, and the presence of symptoms. Further studies are imperative to refine treatment strategies and enhance patient care outcomes., Competing Interests: The authors have no funding and conflicts of interest to disclose., (Copyright © 2024 the Author(s). Published by Wolters Kluwer Health, Inc.)

The classification and work-up of adipocytic neoplasms remains challenging and sometimes controversial. Since its initial description by Dr. Enterline, the variety of subtypes and morphological appearances considered to represent the spectrum of atypical lipomatous tumor/well differentiated liposarcoma (ALT/WDL) has expanded, resulting in significant morphologic overlap with other entities, including the recently described atypical spindle cell/pleomorphic lipomatous tumor (ASPLT), conventional spindle cell/pleomorphic lipoma (SPL), and so-called "low-grade" forms of dedifferentiated liposarcoma (DL). Nevertheless, the distinction of most examples of ALT/WDL from lipomas/lipoma-like lesions is easily performed on routine histologic examination but can be problematic if the characteristic atypical cells are poorly represented, particularly in small biopsy specimens, obscured by other cellular elements (inflammation), or simply not recognized. The discovery that lipomatous tumors harbor specific and unique karyotypes and molecular events has resulted in ancillary tests that can help provide more accurate diagnoses, especially in less-than-optimal scenarios. Confirmation of MDM2 immunohistochemical over-expression and detection of the MDM2 gene rearrangement via fluorescent in situ hybridization (FISH) have proven particularly reliable and useful. While FISH analysis for MDM2 gene amplification may be helpful for confirming (or excluding) ALT/WDL, it also can lead to overutilization and overdependence. Furthermore, a small subset of otherwise typical ALT/WDL lack MDM2 gene amplification, employing alternative molecular pathways. The recent recognition of ASPLT has introduced a tumor easily mistaken morphologically for ALT/WDL, often exhibiting bizarre and pleomorphic lipoblasts, but lacking the underlying molecular abnormalities and subsequent risk of dedifferentiation. ASPLT also have overlapping features with the better-established SPL but with a greater tendency to locally recur and more frequent involvement of the distal extremities. The precise criteria separating cellular forms of ALT from what some consider "low grade" forms of DL remains controversial and inconsistently applied, even among individual pathologists within institutions. Given their underlying shared cytogenetic abnormality, molecular testing has no utility in this distinction. Herein is a comprehensive historical overview of ALT/WDL, with updates on its distinction from other similar lipomatous tumors and DL, including practical evidence-based criteria for the appropriate cost-effective use of MDM2 testing., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Introduction: Gastrointestinal (GI) lipomas are rare; however, they are frequent enough to be considered in the differential diagnosis of gut tumours. Here, we present our experience with GI lipomas managed at our institute over the last three years., Methods: This is a retrospective cohort study of patients with GI lipomas managed between January, 2020 and April, 2023 at a tertiary care centre. Clinical presentation, location, and details of surgical procedure were analysed., Results: Ten patients were included, six of whom had lipoma in the colon, one in the stomach, and one each in the duodenum, jejunum, and ileum. The mean age at the time of presentation was 48.8 years (range, 19-77 years), and strong male preponderance (4:1) was noted. Preoperative diagnosis of lipoma on cross-sectional imaging was possible in all patients. All patients were symptomatic and were managed surgically., Conclusions: While GI lipomas are generally considered to be indolent and benign tumours, they can potentially lead to severe complications. The utilisation of computed tomography and magnetic resonance imaging has brought about a significant transformation in diagnosing this condition, enabling preoperative identification in most cases. The surgery offers a definitive treatment with minimal risk of postoperative complications.

We herein report a 27-year-old woman who presented with recurrent knee pain. Laboratory findings revealed minimal inflammation. Arthrography revealed structures resembling adipose tissues. Magnetic resonance imaging showed a high signal intensity of these structures, leading to the diagnosis of lipoma arborescens (LA). Synovectomy was performed. Pathology revealed adipocyte proliferation and B-cell clusters but no T-cell infiltration. A serum cytokine analysis revealed low levels of interleukin-6 and tumor necrosis factor-α compared with patients with rheumatoid arthritis. The pathogenesis of LA remains unclear, but immunostaining and serum cytokine levels may provide valuable data for future investigations.

Abstract: Intraosseous lipoma of calcaneum is a rare cause of heel pain. Calcaneum is a typical site of involvement of IOL. There are only a few published articles regarding calcaneal intraosseous lipoma and one has been reported from Nepal. We report a case of 35 years female who presented with left heel pain for 1 year. The pain was gradually increasing in intensity and was severe enough to refrain her from activities of daily living. She was surgically operated with curettage and filling the defect with bone cement. There is no residual pain at 2.5 years follow up. We briefly review the postulated pathogenesis, clinical manifestations, diagnosis and various modalities of treatment of intraosseous lipoma. An orthopedic surgeon should have high degree of suspicion regarding the uncommon cause of heel pain and its possible management. When conservative methods do not relieve symptoms, surgical excision and filling the defect with bone cement provides long term relief.

The original article was published on February 15, 2024 and corrected on April 15, 2024.The revised version of the article corrects Figure 2. The changes appear in the revised online PDF copy of this article.

Spindle cell lipoma (SCL) is a rare form of lipoma, typically occurring as a mass in the back, shoulder or posterior neck of adult males. Most cases present little diagnostic difficulty on fine needle aspiration (FNA), but can be problematic when the SCL is in an unusual location. The authors report a case in the parotid gland in a 75-year-old man. FNA was paucicellular and showed loose collections of spindle cells with mild to moderate atypia, admixed with ropy collagen fibers on a myxoid background. The nuclei showed occasional angulation, interpreted on FNA as suspicious for myoepithelial tumor or low-grade sarcoma. The subsequent excisional specimen was diagnosed as SCL. On retrospective review of the FNA, an additional finding was recognized: 'naked' nuclei with intranuclear lipid vacuoles and positive immunostaining for S100 protein, consistent with Lochkern cells of mature adipocytes. This case highlights the challenges of diagnosing SCL on cytology when no fat-containing cells are apparent on the smear, and stresses the significance of Lochkern cells as a clue for diagnosis., (© 2024 Wiley Periodicals LLC.)

Spindle cell lipomas are a rare type of lipoma usually presenting in middle-aged to older men, often located on the posterior neck or shoulder; presentation on the foot is exceptionally uncommon. We report a 24-year-old man with spindle cell lipomas on the hallux of his left foot. He experienced an uneventful recovery after excision of the mass. We discuss clinical, radiologic, and histopathologic features of spindle cell lipomas and we review the differential diagnosis at this anatomic site.

Several high-grade pleomorphic sarcoma cases that cannot be classified into any existing established categories have been reported. These cases were provisionally classified into undifferentiated pleomorphic sarcoma (UPS). Some dedifferentiated liposarcoma (DDLS) cases may also have been classified into the UPS category due to the absence of MDM2 amplification or an atypical lipomatous tumor/well-differentiated liposarcoma component. We retrieved and reviewed 77 high-grade pleomorphic sarcoma cases, initially diagnosed as UPS in 66 cases and DDLS in 11 cases. Fluorescence in situ hybridization (FISH) analyses of DDIT3 and MDM2 were performed for available cases. Of the cases successfully subjected to DDIT3 FISH (n = 56), nine (7 UPS and 2 DDLS) showed DDIT3 amplification but no MDM2 amplification. Two UPS cases showed both telomeric (5') and centromeric (3') amplification of DDIT3 or low polysomy of chromosome 12, whereas 5 UPS and 2 DDLS cases showed 5'-predominant DDIT3 amplification. Histopathologically, all cases showed UPS-like proliferation of atypical pleomorphic tumor cells. Immunohistochemically, only one case showed focal nuclear positivity for DDIT3, supporting the previous finding that DDIT3 expression was not correlated with DDIT3 amplification. All three cases with focal MDM2 expression involved 5'-predominant amplification, two of which showed DDLS-like histological features. The majority of cases (7/9) showed decreased expression in p53 staining, suggesting that DDIT3 amplification regulates the expression of TP53 like MDM2. From a clinicopathological perspective, we hypothesize that DDIT3-amplified sarcoma, especially with 5'-predominant amplification, can be reclassified out of the UPS category., Competing Interests: Declaration of competing interest The authors have no conflicts of interest to disclose., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Atypical spindle cell/pleomorphic lipomatous tumor (ASCPLT) is a rare soft tissue neoplasm, commonly arising in the subcutis (more common than deep soft tissue) of limbs and limb girdles during mid-adulthood. ASCPLT is histologically a lipogenic neoplasm with ill-defined margins composed of a variable amount of spindle to pleomorphic/multinucleated cells within a fibromyxoid stroma. ASCPLTs lack MDM2 amplification, but a large subset show RB1 deletion and variable expression of CD34. Though initially thought to be the malignant form of spindle cell lipoma, ASCPLTs are benign with local recurrences (∼10-15%) and no well-documented dedifferentiation or metastasis., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Fat-forming solitary fibrous tumor is a rare and specific subtype of solitary fibrous tumor. In this case, a mass of 8.3 cm in diameter was found in a 59-year-old male patient's right retroperitoneum, as revealed by abdominal contrast-enhanced computed tomography (CT) images. The tumor exhibited a well-circumscribed nature and histological features characterized by a combination of hemangiopericytomatous vasculature and mature adipose tissue, comprising around 70% of the total tumor composition. Immunohistochemistry staining revealed diffuse positive expression of STAT6 and CD34 in the tumor cells. Based on these findings, the final diagnosis was determined to be a fat-forming solitary fibrous tumor located in the retroperitoneum. It is important to consider other potential differential diagnoses, including angiomyolipoma, dedifferentiated liposarcoma, spindle cell lipoma, and atypical lipomatous tumor/well-differentiated liposarcoma., (© 2024. The Author(s).)

Background. Lipomas are common superficial soft tissue tumors of mature adipocytes. In contrast, well-differentiated/dedifferentiated liposarcoma typically presents in the retroperitoneum as large masses. We provide clinicopathologic and follow-up details of 9 retroperitoneal/intra-abdominal benign lipomatous tumors (BLT) and discuss the utility of ancillary fluorescence in situ hybridization (FISH) in distinguishing from their malignant counterparts. Design. Clinicopathologic details and histology of 9 intra-abdominal and retroperitoneal lipomas were studied along with ancillary CD10 immunohistochemistry (IHC) and FISH for MDM2 and CDK4 amplification. Results. There were 6 females and 3 males. Median age at diagnosis was 52 years (range 36-81 years). Seven were identified incidentally and 2 presented with primary complaints. On imaging, 7 were considered suspicious for liposarcoma. Grossly, the tumors ranged from 3.4 to 41.2 cm (median 16.5 cm). Histologically, all cases showed well-differentiated BLT, further classified as lipoma (n = 7; 1 with metaplastic ossification, 2 with prominent vessels, and 4 ordinary lipomas) and lipoma-like hibernoma (n = 2)-the latter 2 showed intramuscular lesions with interspersed brown fat. CD10 IHC showed strong staining in the 2 hibernomas, whereas the staining was weak in the remaining. MDM2 and CDK4 amplification were negative by FISH in all. Follow-up (median 18 months) did not show recurrence on clinical or imaging evaluation. Conclusion. Retroperitoneal/intra-abdominal BLT are extremely rare and are indistinguishable clinically and radiographically from liposarcoma. This necessitates molecular confirmation even when the histology is convincingly benign, for a confident diagnosis. Our cohort shows that conservative excision without removal of abutted organs is sufficient in most cases., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

The current criteria for utilizing MDM2 Fluorescence In Situ Hybridization (FISH) in adipose-derived tumors were first introduced in 2015 and have been widely adopted. However, these criteria may fail to identify some atypical lipomatous tumors / well-differentiated liposarcoma (ALT/WDL) with mature adipocytic morphology in clinical practice, possibly due to the fact that the existing criteria are primarily based on biopsy cases. Hence, a criterion based on resection cases is needed. In this study, we included 87 adipose tissue tumors with mature adipocytic morphology which were first resected, as well as 9 consultation cases and 25 recurrent resection cases. The final diagnosis was based on MDM2 amplification status. Among the 87 first-time resection cohort, MDM2 FISH amplification was observed in only 2 (5%) of the 39 superficial cases. Marginal infiltration was significantly different in both the MDM2 FISH negative and positive groups (p < 0.05). Of the 37 intramuscular tumors, 17 (46%) showed MDM2 FISH amplification. The MDM2 amplification positive group had a larger tumor size than MDM2 amplification negative group (p = 0.042). Tumors of larger size (≥11 cm) were highly correlated with MDM2 amplification (p = 0.003), but still, 35.3% of the MDM2 amplification-positive cases had tumor sizes less than 11 cm. Eight (66.7%) out of twelve retroperitoneal/ pelvic cases were MDM2 FISH positive. Among the 25 recurrent cases, twenty (80%) of them had MDM2 FISH amplification. In conclusion, we recommend MDM2 FISH for: 1. superficial cases with marginal infiltration based on adequate margin sampling; 2. all intramuscular tumors, retroperitoneal/pelvic tumors and recurrent tumors, both in resection cases and biopsy cases., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier GmbH. All rights reserved.)

Lipomas are common benign adipose tissue tumors but are infrequently found in the labia majora, especially at a large size. We report a case of a giant lipoma of the labia majora in a 37-year-old woman diagnosed by imaging methods and successfully treated by surgery. This case highlights the importance of considering lipoma in the differential diagnosis of labial masses and underscores the role of imaging in diagnosis. They need to be differentiated from liposarcoma or omental herniation into Nuck's canal. It also demonstrates the effectiveness of surgical management for large lipomas in sensitive areas, with attention to both medical and aesthetic outcomes.

An interesting case of an abdominal wall swelling near an old operative scar showing epithelial and stromal cells. In this present paper, fine needle aspiration cytology of an inguinal swelling is discussed which may often create diagnostic confusion., (© 2023 John Wiley & Sons Ltd.)

We present a 36-year-old woman with small pelvis lipoma spreading to the gluteal region through the greater sciatic foramen. Resection of lipoma was performed via two accesses (lower median laparotomy and semilunar incision in the gluteal region). The tumor was the content of sciatic hernia that is extremely rare. Combination of surgical approaches can provide favorable outcomes in these patients.