Chondroid lipoma: an update and review

Lipoma-like hibernoma: a rare soft tissue tumor-a case series and review of the literature

Hibernomas are rare and benign lipomatous tumors which consist of lobules of cells derived from brown fat. Less than 200 overall cases are reported in the literature which necessitates the need to report more cases for better understanding of this neoplasm. Hibernomas are slowly progressing, painless tumors most frequently located in the subcutaneous thigh, upper trunk, and neck. Hibernomas generally occur in areas close to the axial skeleton where brown fat used to exist in the fetus and persisted during adulthood. They are rare to be discovered for the first time in older adults, most commonly presenting in adults 20-40 years of age. Core biopsies are simple to perform under local anesthetic and provide pathological differentiation prior to planned excision, hence are recommended, especially with larger lesions. Based on case presentation, watchful waiting for non-growing asymptomatic cases of hibernoma is possible, but more frequent follow-up and/or a core biopsy would be advised to rule out a more aggressive diagnosis. Compared with lipoma-like hibernomas, atypical lipomatous tumor/well-differentiated liposarcoma recurs and might dedifferentiate to a dedifferentiated liposarcoma with the ability to metastasize in up to 5% of the recurrences. Hibernomas, including the lipoma-like variant, are typically treated by surgical excision, rarely recur and do not metastasize. We report two rare presentations of hibernoma and lipoma-like hibernoma. Awareness of this clinicopathological entity is crucial to avoid misdiagnosis as malignant lipomatous neoplasm.

Chondroid lipoma: multimodality imaging in a 9-year-old female

Chondroid lipomas are rare, benign lipomatous tumors that occur most frequently in adults during the fourth decade of life. While a female predominance was observed in the initial series of 20 cases described in 1993, the subsequent 49 reported cases do not support a strong gender predilection. We report a case of a chondroid lipoma presenting in a 9-year-old female as a painless, enlarging, left gluteal mass. This is the second case to be reported in the first decade of life and the fourth pediatric case reported in the literature (age < 21). We review the imaging and pathology findings as well as present a comprehensive review of the current literature.

[Tumors with predominantly adipocytic morphology]

More than 20% of soft-tissue tumors belong to the group of adipocytic neoplasms. Difficulties may occur in the differential diagnosis of lipomas versus atypical lipomatous tumors/well-differentiated liposarcomas, in the distinction of dedifferentiated liposarcomas from other soft-tissue sarcoma entities and in the detailed subtyping of liposarcomas. Especially in biopsies, the correct diagnosis and grading may be hampered due to limited tissue. Because of the ever-increasing molecular-pathological knowledge of soft-tissue tumors and the rising distribution of molecular diagnostic assays in institutes of pathology, differential diagnosis has been facilitated, as more than 90% of adipocytic tumors carry more or less specific genomic alterations. In the following, the most important subtypes of adipocytic tumors are described morphologically and genomically.

Characteristics of chondroid lipoma: A case report and literature review

RATIONALE

Chondroid lipoma (CL) is a rare benign tumor. No relevant epidemiological reports have been published on CL, and there is a lack of uniform diagnostic and treatment criteria for the tumor.

PATIENT CONCERNS

Here, we report a case of CL with a mass on the left buttock for 2 weeks, and further illuminate its diagnosis and treatment.

DIAGNOSIS

The diagnosis of CL was rendered according to the pathological indices.

INTERVENTIONS

The tumor was resected completely under spinal anesthesia.

OUTCOMES

The patient was followed-up for 6 months and showed no tumor recurrence or metastasis and there was resolution of the patient's lower-limb numbness and pain.

LESSONS

The case study presented here provides evidence that CL could be effectively diagnosed by using ultrasound, puncture or biopsy, and/or magnetic resonance imaging. Furthermore, the patient recovered without any complications after completely resecting the tumor.

A contemporary review of myxoid adipocytic tumors

Myxoid adipocytic tumors encompass a broad heterogeneous group of benign and malignant adipocytic tumors, which are typically myxoid (e.g. myxoid liposarcoma, lipoblastoma and lipoblastoma-like tumor of the vulva) or may occasionally appear predominantly myxoid (e.g. pleomorphic liposarcoma, atypical lipomatous tumor, dedifferentiated liposarcoma, chondroid lipoma, spindle cell/pleomorphic lipoma, atypical spindle cell lipomatous tumor and atypical pleomorphic lipomatous tumor). There have been significant advances in recent years in classification and understanding the pathogenesis of adipocytic tumors, based on the correlation of histologic, immunohistochemical, and cytogenetic/molecular findings. Despite these advances, the morphologic diagnosis and accurate classification of a myxoid adipocytic tumor can be challenging due to major morphologic overlap between myxoid adipocytic and non-adipocytic tumors. This article will provide a review on the currently known morphological, immunohistochemical and molecular features of myxoid adipocytic tumors and their differential diagnosis.

Chondroid lipoma of the neck: a case report

Background

Chondroid lipoma, first described in 1993 by Meis and Enzinger, is a very rare lipomatous tumor. Because it is a benign tumor, it does not require radiotherapy, chemotherapy, or extensive resection. However, histologically, it is often confused with a sarcoma. It is crucial to differentiate chondroid lipoma from sarcoma to avoid choosing an inappropriate treatment strategy. Although MRI, radiography, and ultrasound have been used to evaluate chondroid lipomas, imaging cannot accurately differentiate chondroid lipoma from sarcoma.

Case presentation

A 39-year-old man presented to a local clinic with a 1-month history of a painless mass in his left neck. Results of a needle biopsy suggested an atypical lipomatous tumor, and the patient was referred to our hospital. Physical examination revealed a hard and mobile mass in the left neck. Plain X-ray radiographs showed an absence of calcification in the soft tissue mass. MRI revealed a well-defined and lobulated mass, and on T1-weighted images, the lesion showed heterogeneity, with higher signal intensity than that of muscle. On T2-weighted images, the septum had low-signal intensity. On T2-weighted fat-suppressed images, the signal of the mass was completely suppressed. The SUV_max of the mass on FDG PET was 1.84. An additional needle biopsy was performed, and on the basis of the results, we arrived at a diagnosis of well-differentiated liposarcoma. The mass was resected marginally. Macroscopically, the mass was encapsulated and markedly harder than well-differentiated liposarcoma. Histologically, the tumor was composed of myxoid and cartilaginous matrix, and mature fat cells and lipoblast-like cells were present. The final diagnosis was chondroid lipoma, and no recurrence was observed 1 year after surgery.

Conclusions

Chondroid lipoma is an extremely rare benign soft tissue tumor that is often confused with sarcoma. It is very important to differentiate chondroid lipoma from sarcoma when the SUV_max value of the mass is low, even when biopsy results suggest that it is a sarcoma.

Well-differentiated liposarcoma with chondroid metaplasia in the auricle of a dog

A 13-year-old spayed female dog had a mass in the left auricle. Grossly, connection between the mass and original auricular cartilage was not recognized. The mass was unencapsulated and contained multiple islands of mature hyaline cartilage and neoplastic adipocytes. The neoplastic cells comprised predominant mature adipocytes, scattered lipoblasts and irregular round to spindle cells with moderate atypia. The atypical cells occasionally had lipid droplets. A diagnosis of well-differentiated liposarcoma (WDL) with chondroid metaplasia was made. This is the first report for liposarcoma with chondroid metaplasia in the auricle of domestic animals.

Spectrum of Fat-containing Soft-Tissue Masses at MR Imaging: The Common, the Uncommon, the Characteristic, and the Sometimes Confusing

Fat-containing tumors are the most common soft-tissue tumors encountered clinically. The vast majority of fat-containing soft-tissue masses are benign. Lipomas are the most common benign fat-containing masses and demonstrate a characteristic appearance at magnetic resonance (MR) imaging. Less common benign soft-tissue masses include lipoblastoma, angiolipoma, spindle cell lipoma/pleomorphic lipoma, myolipoma, chondroid lipoma, lipomatosis of nerve, lipomatosis, hibernoma, and fat necrosis. Well-differentiated liposarcomas (WDLPSs)/atypical lipomatous tumors (ALTs) are locally aggressive soft-tissue masses that do not metastasize. Biologically more aggressive liposarcomas include myxoid, pleomorphic, and dedifferentiated liposarcomas. At MR imaging, lipomas typically resemble subcutaneous fat but may contain a few thin septa. The presence of thick, irregular, enhancing septa and nonfatty soft-tissue mass components suggests liposarcoma rather than lipoma. However, benign lipomatous lesions and WDLPS/ALT often have overlapping MR imaging findings. Distinguishing WDLPS/ALT from a benign lipomatous lesion or from fat necrosis at imaging can be challenging and often requires histologic evaluation. We present the spectrum of fat-containing masses, using the World Health Organization classification of adipocytic tumors, with an emphasis on commonly encountered lesions, characteristic MR imaging findings associated with specific tumors, and overlapping MR imaging findings of certain tumors that may require histologic sampling. We also briefly discuss the role of molecular markers in proper characterization and classification of fat-containing soft-tissue masses. (©)RSNA, 2016.

[Adipocytic tumors]

Adipocytic tumors are the most common mesenchymal neoplasms, liposarcoma accounting for approximately 20% of soft tissue sarcomas. The differential diagnosis between benign and malignant tumors is often problematic and represents a significant proportion of consultation cases. The goal of this article is to review liposarcoma subtypes, the main benign adipocytic neoplasms: lipoblastoma, hibernoma, spindle/pleomorphic cell lipoma, chondroid lipoma, as well as non adipocytic neoplasms with a lipomatous component such as lipomatous solitary fibrous tumor, emphasizing on practical differential diagnosis issues, and immunohistochemical and molecular tools allowing their resolution.

Chondroid lipoma of the tongue: a report of two cases

BACKGROUND

Chondroid lipoma affecting the oral cavity is rare and usually presents as a polyp of benign clinical appearance which is easily excised. However, the histopathological features of chondroid lipoma resemble liposarcoma due to the presence of lipoblasts and lack of mature cartilage.

CASE REPORTS

The clinicopathological features of two cases of chondroid lipoma of the dorsum of the tongue, one in a 66-year-old woman and the other in a 43-year-old man, are described.

CONCLUSION

Once the diagnosis had been established, no treatment other than surgical excision was necessary and in neither case has there been recurrence in two years of follow-up.

Sarcoma diagnosis in the age of molecular pathology

Mesenchymal neoplasia presents numerous challenges to pathologic classification. Histologic features can be deceiving, and traditional immunohistochemical markers of differentiation may be of little use in narrowing the diagnosis. Fortunately, great strides have been made in unraveling the genetic and genomic alterations associated with both sarcomagenesis and benign neoplasia. In turn, these advances have led to an expansion of the available diagnostic toolkit for sarcoma pathology. In order to assist the practicing pathologist in integrating these tools into their repertoire, this article will discuss some of the latest advances in sarcoma diagnosis, including an update on translocation-associated sarcomas, and will review a number of sarcoma-specific immunohistochemical studies developed over the past decade. Some of the potential uses and pitfalls of commonly used tests will be addressed. Finally, the discussion will briefly touch upon the impact that advances in molecular technologies, particularly targeted gene expression analysis, may have on altering the face of diagnostic pathology.

Updates on the cytogenetics and molecular cytogenetics of benign and intermediate soft tissue tumors

SOFT TISSUE TUMORS ARE CLASSIFIED ACCORDING TO THEIR HISTOLOGICAL RESEMBLANCE TO NORMAL ADULT TISSUES AND CAN BE GROUPED INTO THE FOLLOWING CATEGORIES BASED ON METASTATIC POTENTIAL: benign, intermediate (locally aggressive), intermediate (rarely metastasizing) and malignant. Over the past two decades, considerable progress has been made in our understanding of the genetic background of soft tissue tumors. Traditional laboratory techniques, such as cytogenetic analysis and fluorescence in situ hybridization (FISH), can be used for diagnostic purposes in soft tissue pathology practice. Moreover, cytogenetic and molecular studies are often necessary for prognostics and follow-up of soft tissue sarcoma patients. This review provides updated information on the applicability of laboratory genetic testing in the diagnosis of benign and intermediate soft tissue tumors. These tumors include nodular fasciitis, chondroid lipoma, collagenous fibroma (desmoplastic fibroblastoma), giant cell tumor of tendon sheath (GCTTS)/pigmented villonodular synovitis (PVNS), angiofibroma of soft tissue, myxoinflammatory fibroblastic sarcoma (MIFS) and ossifying fibromyxoid tumor (OFMT).