Giant pleomorphic lipoma in patient with multiple osteochondromatosis.

Pleomorphic lipomas are infrequent soft tissue tumours with pseudosarcomatous behaviour. Their polymorphism provides them certain characteristics that may resemble malignancy, which may mislead the initial diagnosis. The presented case report is a 45-year-old man with a giant growing tumour on the left cervicoscapular region initially categorised as a liposarcoma by magnetic resonance with a final confirmed diagnosis of pleomorphic lipoma after the surgical resection and the examination of the pathologist. The patient presented important functional restriction of the upper left extremity, which decreased after surgical resection, improving the quality of life.

Pleomorphic Lipoma of the Parotid Gland: A Potential Cytological Pitfall.

Pleomorphic lipoma is an uncommon benign adipocytic tumor that arises from the subcutis. It has no risk of recurrence, metastasis or malignant transformation. The cytological findings of pleomorphic lipoma are often overdiagnosed as suspicious of malignancy owing to the pleomorphic morphology of the floret giant cells. We present a rare case of pleomorphic lipoma of the parotid gland which was misdiagnosed as a malignant tumor on fine needle aspiration cytology. Histopathological examination and positive expression for CD34 helped to arrive at the final diagnosis. Awareness about this rare entity will prevent overdiagnosis as a malignant tumor and unnecessary radical resections for this benign tumor.

Atypical lipomatous tumor/well differentiated liposarcoma and related mimics with updates. When is molecular testing most cost-effective, necessary, and indicated?

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.

A Case of Nasopharyngeal Pleomorphic Lipoma.

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.

Spindle Cell Lipoma and Pleomorphic Lipoma: An Update and Review.

Spindle cell lipoma (SCL) is a benign adipocytic tumor that primarily occurs in the subcutis of the posterior neck, upper back, and shoulder, particularly of middle-aged males. SCL and pleomorphic lipoma (PL) represent a morphological spectrum of one disease process. The lesion typically presents as a relatively small (<5 cm), mobile, slow-growing, painless mass. Magnetic resonance imaging reveals the lesion to be a well-defined subcutaneous mass with a mixture of adipose and non-adipose components. Intense enhancement of the non-adipose component is seen after contrast administration. Histologically, SCL is composed of variable distributions of mature adipocytes, bland spindle cells and ropey collagen bundles and PL also contains pleomorphic and multinucleated floret-like giant cells. By immunohistochemistry, the spindle and pleomorphic/floret-like giant cells of SCL/PL are diffusely positive for CD34 and show loss of nuclear RB transcriptional corepressor 1 (RB1) expression. Recent cytogenetic and molecular genetic studies have shown heterozygous deletions of 13q14, including the RB1 gene. SCL/PL can be successfully treated with simple excision, with a very low recurrence rate. Knowledge of these peculiar tumors is important because it can mimic a variety of benign and malignant soft-tissue tumors. This review provides an updated overview of the clinical, radiological, histopathological, cytogenetic, and molecular genetic features of SCL/PL.

Atypical spindle cell/pleomorphic lipomatous tumour (ASPLT): A report of three FNA cases and comparison with spindle cell/pleomorphic lipoma cytopathology.

INTRODUCTION: Atypical spindle cell/pleomorphic lipomatous tumour (ASPLT) is an infrequently appreciated benign lipomatous neoplasm newly accepted into the most recent WHO classification of soft tissue tumours. MATERIALS AND METHODS: Our cytopathology files were searched for examples of ASPLT and spindle cell/pleomorphic lipoma (SCPL) having histopathological verification. Conventional fine needle aspiration (FNA) biopsy smears were performed using standard techniques. RESULTS: Eleven patients including three cases of ASPLT and eight of SCPL (M:F = 4.5:1; age range: 39-97 years, mean age = 60 years) met the inclusion criteria. FNA biopsy sites included extremity (5, 45%), trunk (3, 27%), and head/neck (3, 27%). All aspirates were from primary neoplasms. FNA diagnoses of ASPLT cases were spindle cell lipomatous neoplasm, fibrotic low-grade SC neoplasm, and myxoid lipomatous neoplasm. Eight SCPL cases were diagnosed as spindle cell neoplasm (3), spindle cell lipoma (SCL) (1), pleomorphic lipoma (1), suspicious for SCL (1), benign adipose tissue (1), and benign spindle cells and connective tissue (1). Ancillary testing in two ASPLT cases showed positive CD34 and negative MDM2 immunostain in one, and negative FISH results for MDM2 and DDIT3 in another. CONCLUSION: ASPLT is a novel lipomatous neoplasm simulating primarily SCPL and atypical lipoma/well-differentiated liposarcoma. Diligent cytomorphological observation, clinical information, and ancillary testing may allow for its specific recognition using FNA biopsy.

Atypical spindle cell lipomatous tumor of the tongue: A rare entity arising in an unusual location.

Atypical spindle cell/pleomorphic lipomatous tumor (ASCPT) constitutes an emerging entity of lipomatous tumors. It is a benign tumor. It occurs typically in limbs and limb girdles. The occurrence in oral cavity is unusual. The diagnosis of this neoplasm is challenging. Herein, we report a case of ASCPT arising in the tongue.

Histopathologic and genetic findings in atypical spindle cell/pleomorphic lipomatous tumors and atypical pleomorphic fibromas.

BACKGROUND: Spindle cell lipomas, pleomorphic lipomas (SCL/PLs), and pleomorphic fibromas (PF) are tumors with loss of retinoblastoma (RB). The latest World Health Organization classification includes a category of atypical spindle cell/pleomorphic lipomatous tumors (ASPLT), which encompasses tumors in this spectrum that show atypical histopathologic features. We have observed PFs that show similar atypical features. METHODS: Cases of SCL/PL and PF with atypical features were collected from tissue archives between 2010 and 2019. Genetic alterations were investigated using array comparative genomic hybridization (aCGH). RESULT: Of 15 cases found, most tumors were dermal based with fibrocytic or fibroadipocytic appearance and occasional lipoblasts. All cases had a high proliferation index with atypical mitotic figures in 71% of cases. Chromosome 13q loss was present in all cases with CGH data. Additional recurrent chromosomal losses included 17p, 16q, 17q, 20p, 4, and 10. No recurrence was found in limited follow-up. CONCLUSIONS: ASPLTs are characterized by loss of RB, prominent nuclear pleomorphism, mitotic activity including atypical mitotic figures, and genomic instability with multiple chromosomal aberrations. A similar group of tumors with these histopathologic features lacks lipomatous differentiation, and we propose the diagnosis of atypical PF as a fibromatous variant of ASPLT. Limited clinical follow-up appears benign.

A Diagnostic Dilemma in Fine-Needle Aspiration Cytology: Spindle Cell/Pleomorphic Lipoma.

Pleomorphic lipoma is an uncommon, pseudosarcomatous lesion. It is characterized by the pleomorphic appearance on cytology and histology, follows a benign course, with a low rate of recurrence after complete excision, and has no risk of metastasis. Here, we describe a case of pleomorphic lipoma/spindle cell lipoma in a 41-year-old man who presented with a slow-growing mass on the inner aspect of the left thigh. On fine-needle aspiration cytology, it was reported as a cellular nerve sheath tumour followed by a wide excision sample sent for histopathological examination, which revealed spindle cells exhibiting pleomorphism with mature adipocytic cells and multinucleated floret cells in a myxoid background. It was reported as pleomorphic lipoma on histological examination.

What's new in adipocytic neoplasia?

Adipocytic tumours are among the most common mesenchymal neoplasms, and constitute a clinically, biologically and pathologically diverse group. Their wide histological spectrum and frequent morphological overlap have made classification and diagnosis challenging, with accurate classification being critical because of the considerable differences in prognosis and management between morphologically overlapping neoplasms. Ongoing advances in molecular genetics have aided significantly to our understanding of these neoplasms, with continuing evolution in classification. This review summarises the new developments in benign and malignant adipocytic neoplasms, with discussion of new entities and genetic findings, updates on the clinical and morphological spectrum, and the use of diagnostic immunohistochemistry and molecular markers in the differential diagnosis.

Transoral robotic resection of unusual spindle cell/pleomorphic lipoma of the larynx.

Spindle cell/pleomorphic lipoma (SC/PL) is a subcutaneous mass usually localised on nape, shoulder or upper back. It is a benign lipogenic tumour composed of primitive CD34-positive spindle cells, floret-like multinucleated giant cells and mature adipocytes. Complete surgical excision is the optimal treatment. This unusual tumour in the larynx has only been reported in the medical literature once and was treated surgically by open approach. Actually, transoral robotic surgery (TORS) is most suitable because provides tridimensional magnified view plus a greater mobility with instruments, allowing complete and safe removal of the supraglottic mass, allowing rapid healing and recovery. We present the first case of a SC/PL of larynx managed with TORS. Four hours after surgery, the patient was able to take a soft diet and was discharged 2 h later. The follow-up showed an excellent clinical and functional outcome.

The Rapidly Expanding Group of RB1-Deleted Soft Tissue Tumors: An Updated Review.

The classification of soft tissue tumors has evolved considerably in the last decade, largely due to advances in understanding the pathogenetic basis of many of these, sometimes rare, tumors. Deletion of Retinoblastoma 1 (RB1), a well-known tumor suppressor gene, has been implicated in the tumorigenesis of a particular group of soft tissue neoplasms. This group of so-called "RB1-deleted soft tissue tumors" has been rapidly expanding in recent years, currently consisting of spindle cell/pleomorphic lipoma, atypical spindle cell/pleomorphic lipomatous tumor, pleomorphic liposarcoma, myofibroblastoma, cellular angiofibroma, and acral fibromyxoma. Most of these neoplasms, except pleomorphic liposarcoma, are considered benign entities and are mainly described in the older adult population. This article will review the currently known morphological, immunohistochemical, and molecular features of this heterogeneous group of mesenchymal tumors with an emphasis on differential diagnosis.

A Reappraisal of Superficial Pleomorphic Liposarcoma.

OBJECTIVES: Superficial pleomorphic liposarcoma (PL) has a favorable prognosis compared to deeply seated PL. Given developments in the classification of lipomatous neoplasms, we reappraised a series of cases. METHODS: Retrospective clinicopathologic evaluation and genome-wide single-nucleotide polymorphism (SNP) microarray studies were performed for cases previously designated superficial PL. RESULTS: Four cases were identified (age, 48-70 years). Two were dermally confined, whereas two were superficial subcutaneous; no recurrences or metastases were reported. Tumors demonstrated pleomorphic spindled morphology with variable cellularity. Multivacuolated atypical lipoblasts were focal in 3 and abundant in 1. Dermal tumors demonstrated atypical cells within sclerotic collagen. Genome-wide SNP microarray studies revealed consistent gains and losses, including losses at the 13q14.2 locus encompassing RB1 and DLEU2 and deletion/disruption of the TP53 locus. Although subcutaneous examples showed genomic changes similar to deep PL, the dermal examples showed fewer genetic alterations, including changes reported in the spectrum of atypical spindle cell/pleomorphic lipomatous tumors (ASPLT). All lacked MDM2 amplification. CONCLUSIONS: Careful integration of histologic and genetic features may improve classification of lipomatous neoplasms with atypia, allowing reclassification of some superficial PL as ASPLT.

Soft Tissue Special Issue: Selected Topics in the Pathology of Adipocytic Tumors.

Our understanding of adipocytic tumors classification and diagnosis continues to evolve. We present a brief review and updated summary of selected adipocytic tumors involving the head and neck region. For the practicing pathologist, knowledge of these established and emerging entities is critical for the correct pathologic diagnosis and treatment of the patient.

Primary Pleomorphic Lipoma of the Parotid Gland with Prominent Myxoid Change: Report of a Rare Case Mimicking Carcinoma Ex Pleomorphic Adenoma on Fine Needle Aspiration Cytology.

We present a case of a primary 2.5 cm pleomorphic lipoma of the right parotid gland with prominent myxoid change which on FNA displayed features that mimicked a carcinoma or sarcoma ex pleomorphic adenoma. The patient was a 79 year old man with no oncological history or tumor elsewhere. On immunohistochemistry the neoplastic cells strongly expressed CD34. There was no expression of retinoblastoma protein, smooth muscle actin, S100-protein or cytokeratins (AE1/3 and CAM5.2). The Ki-67 proliferation index was low (< 2%). Fluorescence in situ hybridization was negative for MDM2 gene amplification.

What's new in adipocytic neoplasia?

Adipocytic tumors are frequently encountered in routine practice, and while the vast majority represent commonly encountered tumor types (e.g., benign lipoma), the heterogeneity and rarity of other adipocytic neoplasms can pose diagnostic challenges. Atypical and malignant adipocytic tumors account for approximately 20% of all sarcomas. The 2013 World Health Organization (WHO) classification of soft tissue and bone tumors recognizes four major liposarcoma subtypes, characterized by distinct clinical behavior, distinctive morphologies, as well as unique genetic findings: atypical lipomatous tumor/well-differentiated liposarcoma, dedifferentiated liposarcoma, myxoid liposarcoma, and pleomorphic liposarcoma. Since the publication of the 2013 WHO classification of soft tissue and bone tumors, the most notable change in the category of adipocytic tumors has been made in the clinicopathologic and molecular characterization of the heterogeneous but distinct group of "atypical low-grade adipocytic neoplasms with spindle cell features," for which the term atypical spindle cell/pleomorphic lipomatous tumor has been proposed. Another substantive change in the group of adipocytic tumors is the introduction of pleomorphic myxoid liposarcoma (myxoid pleomorphic liposarcoma) as an apparently novel subtype of aggressive liposarcoma, especially occurring in children and young adults with a predilection for the mediastinum. This review will further focus upon the diagnostic criteria of these novel emerging entities in the group of adipocytic tumors.

Pleomorphic lipoma in the anterior mediastinum: A case report.

BACKGROUND: Pleomorphic lipoma (PL) is a rare benign mesenchymal tumor occurring predominantly in middle-aged and elderly men. It is typically found in the subcutaneous tissue of the posterior neck, back, and shoulders. There have also been a few reported cases in the face, scalp, and upper extremities. Currently, there is no report on its occurrence in the anterior mediastinum. CASE SUMMARY: Herein, we report the case of a 67-year-old woman diagnosed with PL in the anterior mediastinum. The tumor was removed by thoracoscopic surgery. There was no recurrence during the 24-mo follow-up period, and the prognosis was good. Most PL are located on the skin surface. However, they may also occur within the body, even in the mediastinum. CONCLUSION: PL occurring in the anterior mediastinum is rare, and it may be differentiated from other tumors.

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.

Updates in spindle cell/pleomorphic lipomas.

Spindle cell/pleomorphic lipomas are benign lipomatous neoplasms that show loss of RB1 and classically harbor components of mature adipose tissue, bland spindled cells and ropy collagen. This review highlights the clinicopathologic features and morphologic spectrum of spindle cell/pleomorphic lipoma, discusses an updated differential diagnosis, and provides a practical diagnostic strategy for spindle cell/pleomorphic lipomas with atypical clinical presentations.