Bilateral hibernomas in the femoral regions of a dog.

A 14-year-old intact male Chihuahua dog was presented with masses located between the biceps femoris and adductor muscles in both hind limbs. Based on histopathological, immunohistochemical, and ultrastructural findings, we diagnosed these masses as bilateral hibernomas in the femoral regions. The dog had no evidence of recurrence or metastasis of the hibernomas through a 4-month postoperative follow-up. This is apparently the first report of bilateral hibernomas in the femoral regions of a dog. Key clinical message: Bilateral hibernomas should be considered as a differential diagnosis for masses occurring in the femoral regions of dogs.

Hibernomes bilatéraux dans les régions fémorales d'un chien. Un chien Chihuahua mâle intact de 14 ans a été présenté avec des masses situées entre le biceps fémoral et les muscles adducteurs des deux membres postérieurs. Sur la base des résultats histopathologiques, immunohistochimiques et ultrastructuraux, nous avons diagnostiqué ces masses comme des hibernomes bilatéraux dans les régions fémorales. Le chien n'avait aucun signe de récidive ou de métastases des hibernomes au cours d'un suivi postopératoire de 4 mois. Il s'agit apparemment du premier rapport d'hibernome bilatéral dans les régions fémorales d'un chien.Message clinique clé:Les hibernomes bilatéraux doivent être considérés comme un diagnostic différentiel pour les masses survenant dans les régions fémorales des chiens.(Traduit par Dr Serge Messier).

DDIT3-amplified or low-polysomic pleomorphic sarcomas without MDM2 amplification: Clinicopathological review and immunohistochemical profile of nine cases.

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.

A case of fat-forming solitary fibrous tumor that is prone to be confused with liposarcoma.

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.

[Small pelvis lipoma spreading to the gluteal region]. / Lipoma malogo taza i yagodichnoi oblasti.

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.

Atypical Spindle Cell/Pleomorphic Lipomatous Tumor.

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.

Fine needle aspiration of spindle cell lipoma-Lochkern cells as a clue for diagnosis: A case arising in the parotid gland.

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.

Intra-Abdominal and Retroperitoneal Benign Lipomatous Tumors-An Extremely Rare Mimic of Liposarcoma and its Diagnostic Challenge.

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.

All groin swellings are not lipoma.

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.

MDM2 FISH testing criteria in adipose tissue tumors with mature adipocytic morphology - A resection case-based study.

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.

Massive anterior mediastinal lipoma causing cardiac arrest in a middle-aged male: a case report and literature review.

Lipoma is a common benign soft tissue tumor, but its size and location can lead to serious issues. We report a case of a 48 year-old male patient who experienced sudden cardiac arrest outside the hospital. After resuscitation and examination, we determined that this was due to a massive mediastinal lipoma compressing the lungs, leading to respiratory failure and pulmonary encephalopathy, ultimately resulting in cardiac arrest. This case serves as a reminder to promptly identify and manage chest lipomas to avoid compression and functional impairment of the respiratory system. Early evaluation and treatment of massive lipomas are crucial for preventing complications.

A Giant Dendritic Fibromyxolipoma in the Right Thorax: A Rare Entity.

Dendritic fibromyxolipoma (DFML) is an uncommon benign tumor. We report the first DFML in the right thorax of a child. An 11-year-old girl was admitted because of a giant tumor in the right thorax. An enhanced chest CT scan indicated a thoracic mass with mild enhancement. Thoracoscopic biopsy revealed that the tumor was composed of stellate and spindle cells embedded within abundant myxoid stroma. Additionally, mature adipocytes, cytoplasmic dendritic processes, short strands of keloidal-type collagen, and plexiform blood vessels were observed. Immunohistochemical staining indicated positive for CD34 and BCL-2. DDIT3 alteration or MDM2 amplification were not observed. The diagnosis of DFML was considered, and complete tumorectomy was performed. In conclusion, definite diagnosis of DFML should be made according to the pathologic features. Accurate diagnosis is crucial to avoid overtreatment because DFML potentially can be mistaken for more aggressive neoplasms.

Diagnosis and management of bilateral lipoma of the middle ear.

INTRODUCTION: Middle ear lipomas are rare, accounting for less than 1% of all middle ear tumours. To our knowledge there have been only 16 reported patients with middle ear lipoma. Only one of these had bilateral congenital middle ear lipomas. The aim of this review is to comprehensive overview the diagnosis and management of congenital lipomas of the middle ear. METHODS: A literature review was performed searching multiple data bases, using the key words "middle ear", AND "lipoma", AND "congenital". A total of 116 articles were identified. One hundred were excluded on various criteria, leaving 16 articles for detailed review. Additionally, we report the second case of bilateral congenital middle ear lipoma. RESULTS: Based on this case report and literature review, the incidence of middle ear lipomas is greater in paediatric patients than in adult patients. Middle ear lipomas are distributed evenly between males and females. Three patients had recognised genetic syndromes, while five had prior ventilation tube placement. Clinically patients present with conductive hearing loss and middle ear effusions. In some cases, presence of a white or yellow mass behind the anterior aspect of the tympanic membrane is recognised. The most common location of the masses is in the anterosuperior quadrant of the middle ear, the site of predilection for small congenital cholesteatomas. An MRI scan is most useful in distinguishing between lipoma and cholesteatoma. All cases reported surgical excision of the middle ear lipoma. There was no evidence of recurrence noted up to 4 years follow up. CONCLUSION: Though rare, congenital lipomas of the middle ear should be a differential diagnosis of a middle ear masses. Early identification can allow surgical lipoma resection with minimal disruption to the ossicular chain. Though there is currently no consensus regarding management, surgical removal and appropriate reconstruction of the ossicular chain if needed, is appropriate.

Biology and Management of Deep-seated Atypical Lipomatous Tumor of the Extremities.

Adipocytic neoplasms are frequently encountered in clinical practice. Atypical lipomatous tumor (ALT) is a locally aggressive but non-metastasizing adipocytic neoplasm that primarily occurs in the proximal extremities of middle-aged to older adults. Histologically, ALT is divided into adipocytic (lipoma-like), sclerosing and inflammatory subtypes. The sclerosing subtype is an unfavorable prognostic factor for local recurrence. ALT is characterized by supernumerary ring and/or giant rod chromosomes. These rings and giant markers invariably contain amplified sequences originating from the long arm of chromosome 12, including the MDM2 proto-oncogene (MDM2) and cyclin-dependent kinase 4 (CDK4) gene. MDM2 and/or CDK4 nuclear immunopositivity is present in most cases. Confidently differentiating deep-seated ALT from deep-seated ordinary lipoma is often difficult on imaging. Moreover, the sclerosing subtype may mimic a higher grade liposarcoma. Detection of MDM2 amplification by fluorescence in situ hybridization would be helpful diagnostically for ALT in more difficult cases. The standard treatment for deep-seated ALT is surgery. Although there is no consensus on the best surgical approach for deep-seated ALT of the extremities, the use of marginal resection is acceptable to preserve musculoskeletal function. This review provides an overview of the current knowledge on the clinical and imaging characteristics, pathogenesis, histopathology, and management of deep-seated ALT of the extremities.

[Small bowel volvulus due to a giant mesenteric lipoma]. / Zavorot tonkoi kishki, obuslovlennyi gigantskoi lipomoi bryzheiki.

Mesenteric lipomas are very rare. They are asymptomatic in most cases, but some patients can develop certain complications such as small bowel volvulus and acute small bowel obstruction. We report a 78-year-old patient with giant mesenteric lipoma complicated by jejunum volvulus and acute small bowel obstruction. The patient underwent laparotomy, en-bloc resection of small bowel, mesentery and lipoma followed by side-to-side anastomosis.

[Pancreatic lipomatous hamartoma: A case report and literature review]. / Hamartoma lipomatoso pancreático: Reporte de caso y revisión de la literatura.

Pancreatic hamartomas (PH) are extremely unusual non-neoplastic tumor-like lesions and accounts for <1% of all hamartomas. Moreover, there is a distinct variant of PH denominated Pancreatic lipomatous hamartoma (PLH), that is even rarer, with only 5 cases, including the present case, reported in the literature. PLH lacks well-defined features and clinically can be mistaken with other lipomatous lesions of the pancreas, including lipoma, pancreatic lipomatosis, PEComa, liposarcoma, and malignant tumors with lipomatous components. Here, we describe a case of PLH in a 70-year-old male with abdominal pain and a lesion, which was preoperatively diagnosed as a pancreatic no functional low-grade neuroendocrine tumor, and subsequent underwent a laparoscopic enucleation of the tumor. The postoperative pathology and immunohistochemical analyses confirmed the diagnosis of PLH.

Pure uterine lipoma - a paradoxical rarity.

Pure uterine lipomas are extremely rare benign uterine tumors. This paper presents the case of a 68-year-old patient with symptomatic leiomyoma-like fundus formation on ultrasound. A hysterectomy was performed with anterior vaginal plastic surgery as a treatment option for concomitant cystocele grade II. Histological diagnosis of pure uterine lipoma with S-100 positive immunohistochemical staining was confirmed. This case shows us that uterine lipoma clinically and diagnostically mimics myoma very well. We believe that surgery as a therapeutical approach is justified in symptomatic patients.

Presentation of multiple painful subcutaneous nodules: Dercum's disease, a rare variant of lipoma.

A woman in her 50s presented to her general practitioner (GP) with an 8-month history of multiple painful subcutaneous nodules of various sizes in her trunk and limbs. Her previous GP made the clinical diagnosis of lipoma when they presented as non-painful nodules 2 years ago. Initial ultrasound demonstrated multiple lipomata with the largest size in the left upper thighs displaying features of subtle internal vascularity, entirely contained within the subcutaneous layer. MRI scan of thigh lesions showed multiple angiolipomas consistent with the entity of Dercum's disease. Subsequent biopsy histology confirmed the image diagnosis of angiolipoma. She was referred to a musculoskeletal oncological surgeon for evaluation and reassurance regarding optimising medical management of her associated obesity. Her angiolipoma and obesity are well managed by her GP. This case highlights the diagnostic workup of a rare variant of lipoma, Dercum's disease. The differential diagnosis of multiple painful lipomas was reviewed and discussed, consequently leading to the discussion of managing the associated obesity in this case.

A Sessile Serrated Lesion Overlying a Submucosal Colonic Lipoma: An Endoscopic Rarity Identified Using Artificial Intelligence.

BACKGROUND Lipomas are benign, slow-growing mesenchymal neoplasms, more prevalent in females, with a peak incidence in the fifth to sixth decades of life. Generally, due to their low clinical relevance, they receive little attention in the literature. Uncommon in the colon, lipomas are most often identified as an incidentaloma in asymptomatic patients during colonoscopy, and overlapping with epithelial lesions is a rare finding. Serrated polyps used to be considered as hyperplastic polyps without any malignant potential; however, currently, the serrated pathway accounts for one-third of all colorectal cancers. Here, we describe a rare case of a sessile serrated lesion on a submucosal lipoma identified with the aid of artificial intelligence. CASE REPORT A 60-year-old woman underwent screening colonoscopy for colorectal cancer after a positive fecal immunochemical test. A high-definition colonoscopy with the aid of artificial intelligence (Fujifilm CAD EYE) was performed. A flat lesion at the right colon was diagnosed with white-light endoscopy simultaneously identified by artificial intelligence, which classified the lesion as hyperplastic. Resection was performed through mucosectomy, and a sign of naked fat was observed at the base of the resected lesion. Histopathology of the specimen characterized a submucosal lipoma associated with a sessile serrated lesion. CONCLUSIONS We describe a rare case of sessile serrated lesion on a colon lipoma, identified with the aid of artificial intelligence. We carried out a brief literature review and discussed the main findings and aspects related to the literature.