Spindle cell lipoma: a clinicopathological study with some original observations

Spindle Cell Lipoma and Pleomorphic Lipoma in the Head and Neck: A Comprehensive Study of Six Cases With Review of Literature

BACKGROUND

Spindle cell lipomas (SL) and pleomorphic lipomas (PL) are rare variants of lipomas, occurring predominantly in the head and neck region. Laryngeal SL/PL is very uncommon and causes obstructive symptoms needing immediate intervention. These tumors are often challenging in radiology due to the admixture of elements and the presence of adipose tissue may help in diagnosis. From a surgeon's perspective, understanding the nuances of SL/PL is paramount. Histology is the gold standard for diagnosis; however, it often causes diagnostic challenges in biopsy.  Method: A retrospective review of the clinical and pathologic features of archival cases of SL/PL was performed.

RESULTS

A total of six cases of head and neck region SL/PL were identified. The age of patients ranged from 21 to 58 years and the male-to-female ratio was 5:1. The tumors were distributed in the nape of the neck (n=3), laryngeal region (n=2), and orbit (n=1). Histology in all the cases showed a low-grade neoplasm composed of a variable amount of spindle cells and adipose tissue. The stroma was myxoid in most cases. CD34 was diffusely positive in all the cases.

CONCLUSION

SLs are a rare and uncommon variant of lipoma with a predilection in the head and neck region. They are low-grade neoplasms with a propensity to recur after years. Having knowledge of this tumor can improve surgical outcomes and better patient care.

Superficial fibromas with CTNNB1 mutation

Superficial fibromas are a group of mesenchymal spindle cell lesions with pathomorphological heterogeneity and diverse molecular backgrounds. In part, they may be indicators of an underlying syndrome. Among the best-known entities of superficial fibromas is Gardner fibroma, a plaque-like benign tumor, which is associated with APC germline mutations and occurs in patients with familial adenomatosis polyposis (Gardner syndrome). Affected patients also have an increased risk to develop desmoid fibromatosis (DTF), a locally aggressive neoplasm of the deep soft tissue highly prone to local recurrences. Although a minority of DTFs occur in the syndromic context and harbor APC germline mutations, most frequently their underlying molecular aberration is a sporadic mutation in Exon 3 of the CTNNB1 gene. Up to date, a non-syndromic equivalent to Gardner fibroma carrying a CTNNB1 mutation has not been defined. Here, we present two cases of (sub-)cutaneous tumors with a hypocellular and collagen-rich Gardner fibroma-like appearance and pathogenic, somatic CTNNB1 mutations. We aim to differentiate these tumors from other fibromas according to their histological appearance, immunohistochemical staining profile and underlying somatic CTNNB1 mutations. Furthermore, we distinguish them from locally aggressive desmoid fibromatosis regarding their biological behavior, prognosis and indicated therapeutic strategies. Consequently, we call them CTNNB1-mutated superficial fibromas as a sporadic counterpart lesion to syndromic Gardner fibromas.

Spindle cell lipoma of the tongue: First case report from the Gulf region and review of the literature

Spindle cell lipoma is a histological variant of oral lipomas. In this report, we present the first case from the Gulf region with the most comprehensive literature review. Clinicians should consider rare tumors in the differential diagnoses of oral masses.

Spindle Cell Lipoma With Florid Primary Follicular Lymphocytic Hyperplasia: A Novel Association With Potential Diagnostic Pitfalls

ABSTRACT

Spindle cell lipoma (SCL) is a benign subcutaneous lipomatous neoplasm with a heterogeneous histologic appearance that varies greatly depending on the amount of fat, collagen, and myxoid stroma, which define the multiple subtypes of SCL, such as fat poor SCL, pseudoangiomatous SCL, and dendritic fibromyxolipoma. Cutaneous lymphoid hyperplasia is a spectrum of benign conditions characterized by reactive B-cell and T-cell cutaneous lymphocytic infiltrates. Cutaneous B-cell lymphoid hyperplasia is a heterogeneous group of non-neoplastic conditions that can be observed as reactive phenomena to infections, medications, allergens, or neoplasms and must be distinguished from cutaneous B-cell lymphomas. Here, we report a novel case of spindle cell lipoma, associated with B-cell primary lymphoid follicular hyperplasia, mixed within the tumor in a peculiar pattern, while discussing potential diagnostic pitfalls with low-grade B-cell lymphomas. This is the first report of such association in the literature.

Spindle Cell Lipoma of the Shoulder: A Case Report

Spindle cell lipoma (SCL), an uncommon variant of benign lipomatous tumor, occurs predominantly in the posterior neck or the shoulders. Patients usually present a well-circumscribed and non-aggressive subcutaneous mass. Histopathologically, the mass comprises fat, CD34-positive spindle cells, and ropey collagen on a myxoid matrix. We report a case of left-shoulder SCL in a 45-year-old Saudi male nonsmoker with no known trauma. A soft tissue mass was seen on MRI near the posterior shoulder. It was a 4.5 cm x 3 cm subcutaneous rounded lump with heterogeneous signal intensity. There is no aggressive or invasive feature, and there is no significant fatty content. The mass was surgically excised with no complication. Histological examination revealed a neoplastic lesion constituted of mature adipocyte lobules and proliferation of loosely held bland spindle-shaped cells against a myxoid background. These cells exhibit neither increased mitoses nor nuclear pleomorphism. There were intervening rope collagen bundles. Lipoblasts and atypical stromal cells are also unidentified. At the periphery, a thin capsule was identified. There is no evidence of malignancy. To the best of our knowledge, this is the first reported case in Unaizah, Al Qassim. The correct diagnosis of SCL without a lipogenic component may be made by paying close attention to the clinical setting, histologic characteristics, immunohistochemical profile, and chromosomal abnormalities.

Intradermal Low-Fat Spindle Cell Lipoma: A Case Report

Spindle cell lipoma is a rare benign neoplasm that features a mixture of evenly aligned spindle cells, mature adipocytes, and ropey collagen. Most cases of spindle cell lipoma are found in the subcutaneous tissue, and intradermal spindle cell lipoma is rarely reported. We present a case of intradermal spindle cell lipoma in a 46-year-old female who presented with a 0.7-cm flesh-colored and dome-shaped nodule on the right temple that had developed 6 years ago. This mass was excised, and upon histopathologic examination, an unencapsulated lesion was located in the dermis, which consisted of bland spindle cells, scanty mature adipocytes, rare lipoblasts, and ropey collagen bundles with prominent basophilic myxoid stroma. Immunohistochemical staining showed diffuse positivity for CD34, negativity for the S-100 protein, and loss of retinoblastoma protein expression. Based on these features, intradermal low-fat spindle cell lipoma was diagnosed. No evidence of local recurrence was observed 4 months after excision. Intradermal low-fat spindle cell lipomas are extremely rare and can easily be mistaken for tumors that have similar clinical and histopathological findings. Herein, we report a globally rare case of an intradermal low-fat spindle cell lipoma.

MRI findings of benign tumors and tumor-like diseases of the tongue with radiologic-pathologic correlation

Benign tumors or tumor-like lesions of the tongue are uncommon lesions that comprise a heterogeneous group of neoplasms. Although there are a variety of benign tumors or tumor-like lesions, the imaging appearance of these diseases is not well defined because of a paucity of scientific literature on this topic. Most benign tongue tumors usually appear as submucosal bulges located in the deep portion of the tongue. Their true features and extent may only be identified on cross-sectional images such as CT and MRI. Thus, CT and MRI play an important role in the diagnosis of these unusual lesions. It is important that radiologists be able to identify the characteristic CT and MR imaging features that can be used to narrow the differential diagnosis with increased diagnostic confidence, suggest specific histologic tumor types. In this pictorial essay, we provide insights into the MRI presentations of benign tongue tumors and tumor-like diseases and their radiologic-pathologic correlation. Benign tumors or tumor-like lesions of the tongue described herein include papilloma, lipoma, hemangioma, venous malformations, schwannoma, neurofibroma, epidermoid cyst, and dermoid cyst.

A case of occipital spindle cell lipoma: a case report

Spindle cell lipoma (SCL) is a subtype of lipoma first defined by Enzinger; it accounts for ~1.5% of all fatty tumors. Most cases occur in the posterior neck and shoulders of middle-aged men and rarely in women or the occiput. A 41-year-old woman presented to us with complaints of a mass on her left occiput which had slowly grown in size over six years. We excised the tumor, and pathological findings confirmed the diagnosis of SCL. There was no recurrence one year after the surgery.

Comprehensive Review of Reported Nonclassical Spindle Cell Lipoma Presentations and a Unique Case Report

Introduction:

Spindle cell lipoma (SCL) is a rare subset of benign lipomatous neoplasms, making up approximately 1.5% of all adipocytic neoplasms. Since SCLs were first described in 1975, numerous nonclassical cases have been reported in the literature, with variation in location, cytologic composition, patient demographic, and progression. Although some previous reports review related cases of specific rare presentations or institution-based summaries, no comprehensive summary of published nonclassical SCL case reports has been done.

Methods:

PubMed was queried for nonclassical presentations of SCL from 1978 to 2018. The nonclassical characteristics were analyzed and described. Those with multiple nonclassical features were studied for common characteristics. The Fisher exact test was used, and a P value of 0.05 was determined to be statistically significant.

Results:

We present the first case of a patient with six nonclassical findings: a fast-growing, infiltrating into skeletal muscle, located in two positions on the chin of an 18-year-old African American woman. In this review of the existing nonclassical SCL, we evaluate 125 cases for demographics, location, size, erosion/infiltration, multiple lesions in one individual, and the number of nonclassical findings in one individual. Women and younger than 40-year-old patients significantly present with more than one nonclassical finding.

Conclusions:

Thorough characterization of the rare nonclassical cases of this benign condition could guide diagnostic decision-making and identify trends in disease presentation over time as well as alert the clinician to the increased risk of rapid regrowth or invasion in an individual with nonclassical findings especially young age and female gender.

An Intradermal Spindle Cell Lipoma on the Plantar Hallux in a Patient With Scleroderma and Ehlers-Danlos Syndrome: A Case Report

Spindle cell lipoma (SCL) is a rare variant of lipomas, which predominantly occurs in the regions of shoulder and posterior neck but rarely on the toes. Epidemiological studies have demonstrated increased incidence of cancers in patients with scleroderma. A 28-year-old female with scleroderma and Ehlers-Danlos syndrome developed a painful, skin colored, raised, polypoid lesion on the plantar side of the left hallux for several years. The lesion was surgically excised. Pathological evaluation showed intradermal bland spindle cells associated with delicate ropey/refractile collagen bundles with strong and diffuse cytoplasmic expression of CD34 but negative expression of Rb and S-100, which are consistent with SCL. We report a first case of SCL on the plantar hallux in a young female patient with scleroderma and Ehlers-Danlos disease with clinical presentations, histopathology, and treatment to raise awareness of clinicians to this rare variant of lipomas.

Spindle Cell Lipoma with Ossification Mimicking Atypical Lipomatous Tumor/Well-Differentiated Liposarcoma: A Case Report

Although spindle cell lipoma (SCL) is a subtype of lipoma, the characteristics of SCL are observed in both lipomatous and non-lipomatous tumors. In this article, we present a case of SCL with ossification mimicking atypical lipomatous tumors/well-differentiated liposarcomas (ALTs/WDLs). Considering the findings of magnetic resonance imaging and needle biopsy, which exhibited ALTs/WDLs, marginal resection was performed. Histopathological findings demonstrated mature adipocytes and spindle cells without atypia and no malignant osteoid tissue in the ossified region. In addition, immunohistochemistry (IHC) showed positive staining for CD34, heterogeneous retinoblastoma protein deficiency, and negative staining for mouse double minute 2 homolog (MDM2) and cyclin-dependent kinase. Fluorescence in-situ hybridization showed negative amplification of MDM2. The final diagnosis of the tumor was established using IHC as an extremely rare SCL with ossification.

Spindle Cell Lipoma Occurring in the Submandibular Space: Fifth Case Reported along with a Concise Review of the Literature

Spindle cell lipoma (SCL) is an uncommon histological variant of lipoma that accounts for 1.5% of all adipose tumors. It rarely occurs in the oral cavity. The most common sites of involvement are the buccal mucosa, tongue, lip, alveolar mucosa, gingiva, and palate. Submandibular space is a very rare site of occurrence for SCL. When occurs in this site, SCL mainly involves the 4th-7th decade with a female predominance. Due to wide communications of submandibular space, the actual extent and appearance of the lesions present here gets masked up especially those involving the deeper tissues leading to an inaccurate diagnosis. Wide overlap of clinical and histopathological features of SCL to other clinical pathologies leads to a challenging task for the clinicians to reach an accurate diagnosis. To our knowledge, only four cases of intraoral SCL involving the submandibular region directly or indirectly have been reported in the literature. Here we represent another rare case of SCL in an 18-year-old male patient along with a concise review of the literature. This case appears to be quite rare due to its location (submandibular space), age, and sex of the patient (18/M).

Hypopharyngeal spindle cell lipoma: A case report and review of literature

RATIONALE

Spindle cell lipoma is a rare, uncommon type of benign lipomatous tumor, a distinct group of lipomas composed of mature adipocytes, uniform spindle cells, and multinucleated giant cells associated with ropey collagen. Immunohistochemically, spindle cell lipoma is characterized by the diffuse expression of CD34.

PATIENT CONCERNS

We present a rare case of a 56-year-old man who complained of vomiting out of a smooth and giant mass in the oral cavity provoked by an intra-abdominal pressure increase. Oral examination revealed an elongated mass protruding from the mouth. Computed tomography of the patient showed a mass from left pyriform to oral cavity, with 2.38 × 2.78 × 16.86 cm in size. The flexible fiberscope showed that the pedicle of the elongated mass originated from the posterior wall of the hypopharynx, corresponding to the left pyriform fossa.

DIAGNOSIS

Histopathologically, the tumor was mainly composed of hyperplastic adipocytes, admixed with small blood vessels, and scattered inside adipose tissue spindle cells. The immunohistochemical profile revealed positivity of spindle cells for CD34, negativity for S100, and low proliferation with Ki67, which confirmed the diagnosis of spindle cell lipoma and revealed its benign behavior.

INTERVENTIONS

The patient underwent hypopharyngeal mass resection using transoral suspension laryngoscopy.

OUTCOMES

No recurrence was found after 5 months of follow-up.

LESSONS

Spindle cell lipoma is difficult to diagnose early because of slow growth and subtle symptomatology. This entity should be differentiated from several benign or malignant subtypes of lipomas, including liposarcomas. In this case, the spindle cell lipoma is large and originates from the hypopharynx, which is a rare entity and presents with atypical symptoms. This case gave rise to further studies on the clinical and pathologic characteristics of this tumor in the future.

Dorsal epidural "Spindle Cell Lipoma" in a pregnant female

Background

Spindle cell lipoma (SCL) constitutes just 1.5% of all lipomatous tumors. They typically occur in the upper back and shoulders. Here, we report a 37-year-old female presenting with a SCL in the dorsal epidural thoracic spine, during her 9^th month of pregnancy.

Case Description

A 37-year-old female presented with a subacute (2 months) progressive paraparesis during her ^9th month of pregnancy. The MR showed a dorsal epidural mass at the D8 level. Following a cesarean section, the patient underwent a laminectomy for tumor excision. Microscopically, the lesion proved to be a SCL. At 5-year follow-up, there was no tumor recurrence.

Conclusion

SCL represents a variant of benign lipomas that may occur in the dorsal thoracic spine. Gross total excision may be followed by a benign clinical course without recurrence or malignant degeneration. Very atypical SCLs need closer follow-up to avoid the misdiagnosis of liposarcoma.

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.

Spindle cell lipoma, dorsum of hand in a 4 year old child: A rare entity

Lipogenic tumors are an uncommon entity in children. There are several variants of lipoma, of which spindle cell lipoma is an extremely rare and accounts for only 1.5% of all lipoma diagnosis. Spindle cell lipoma rarely involves distal extremities. We report a 4-year old boy with swelling over dorsum of hand operated for aesthetic purposes. The report also highlights the salient cytological features, which can help differentiate this entity from other closer mimics on aspiration cytology, guiding the surgeon for appropriate management.

Slow-growing buttock mass after failure of incorporation of autologous fat transfer for gluteal augmentation: ultrasound and MRI features

Gluteal augmentation procedures are gaining popularity and encompass a variety of surgical techniques and methods of graft preparation. While surgical history remains essential for diagnosis, the radiologist must avoid pitfalls and rely on imaging features to recognize both the expected appearance and complications of gluteal augmentation procedures. We report a case of a slowly growing buttock mass after gluteal augmentation with autologous fat transfer 1 year after surgery. The potential diagnostic imaging pitfalls and characteristics on ultrasound and contrast-enhanced MRI are discussed. Multiplicity of fat-containing lesions depicted on large field-of-view images and granulated appearance of the intralesional fat on MRI should allow the radiologist to recognize the appearance of failed fat graft incorporation that can present as a slowly growing encapsulated collection with layered fat and fluid contents.

[A CASE OF SPINDLE CELL LIPOMA ARISING IN THE INGUINAL SUBCUTIS: A CASE REPORT]

A 39-year-old man was referred to us for further examination of a right inguinal mass. He had noticed the mass several months prior and had undergone positron emission tomography/computed tomography, which revealed a mass with an SUVmax of 1.48 at the right inguinal subcutis. Magnetic resonance imaging (MRI) showed a well-circumscribed, heterogeneously enhanced adipose tumor 7cm in length, adjacent to the right spermatic cord and corpora cavernosa with clear boundaries. The tumor was a suspected atypical lipomatous tumor (well-differentiated liposarcoma), and he underwent tumor extirpation surgery. At surgery, the right inguinal canal was not opened, and the right spermatic cord and corpora cavernosa were safely spared. The excised specimen was composed of lipomatous tissue macroscopically. Histopathological diagnosis was of a spindle cell lipoma. Spindle cell lipomas are relatively rare, benign tumors, comprising only 1.5% of all lipomatous tumors. They arise most commonly in the shoulder and posterior region of the neck, and rarely develop in the groin. Differential diagnosis includes atypical lipomatous tumors, but radiological diagnosis is often difficult because of similar findings on MRI. Spindle cell lipomas typically present as a subcutaneous tumor, while atypical lipomatous tumors arise in the deep layers of connective tissue. This difference in the site of the tumor may contribute to their differential diagnosis before surgery.

Spindle cell lipoma of the larynx: A case report

INTRODUCTION

Lipomas are rarely found in primary mesenchymal tumors of the hypopharynx and larynx. When they do appear, they often macroscopically resemble a retention cyst or laryngeal nodule. The laryngeal spindle cell lipoma, a variant, is extremely rare.

PATIENT CONCERNS

A 65-year-old woman presented with a 3-month history of pharyngeal paraesthesia. Laryngoscopy revealed the presence of a well-encapsulated, smooth-surfaced, yellowish, pedicled mass on the left epiglottis. Magnetic resonance imaging confirmed the epiglottic mass.

DIAGNOSIS

Following excision of the mass, the diagnosis of an spindle cell lipoma was established and confirmed by immunohistochemistry.

INTERVENTIONS

Surgical excision of the lesion using a controlled-temperature plasma technique (coblation).

OUTCOMES

At the last (4-year) follow-up evaluation, the patient was asymptomatic and without recurrence.

CONCLUSION

SLC involvement of the epiglottis is rare. Coblation is an effective means to remove it.

A Painless Restricted Motion of the Thumb: What Etiology? About An Uncommon Tumor in Uncommon Localization

Lipomas in fingers are rare and account for less than 1% of all cases. As a type of lipoma, the spindle cell lipoma is exceptional and it presents 1.5% of total adipocyte tumors. Moreover, its localization in the thumb is extremely rare. Only three cases have already been reported in adults; our case constitutes the fourth case, which is about a 61-year-old female who presented since 18 months a mass on the ulnar lateral aspect of the thumb. After clinical and radiological assessments, an entire excisional biopsy of the mass was performed. The histopathological analysis confirmed the spindle cell lipoma of the thumb. At the last follow-up of two years, the patient did well with no recurrence and no restricted motion of the thumb. So, although lipomas of the digit are rare, they should be considered a possible etiology of either painful or mechanic restricted motion of the digit.

A Rare Cause of Cough: Tracheobronchial Myxoid Spindle Cell Lipoma

Background

Endobronchial lipomas are a particularly rare form of benign lung neoplasms, with an incidence of 0.1-0.4%. They are often clinically silent, though present with nonspecific symptoms that can result in extensive workup or significant delay prior to diagnosis, as presented in this case. Case Presentation. A 61-year-old male presented with chronic productive cough and occasional dyspnea and a 10-year history of clinically diagnosis of intermittent, exercise-induced asthma, nonresponsive to bronchodilators, and with normal pulmonary function tests. A chest ray showed a band-like opacity in the right middle lobe of the lung and a CT of the chest showed right lung atelectasis with a soft tissue mass in the right main bronchus. The patient underwent bronchoscopy with biopsy, which demonstrated an endobronchial myxoid spindle cell lipoma. The lesion was subsequently removed by a bronchoscopic snare. The patient's asthmatic-like symptomatology resolved after the mass was excised.

Conclusion

Though rare, endobronchial lipomas characteristically present with nonspecific signs and symptoms and thus can be easily mistaken for other medical conditions, delaying diagnosis and prolonging symptoms.

Imaging of spindle cell lipoma

AIM

To review the evaluation, diagnosis, and treatment of spindle cell lipoma (SCL) with emphasis on the location of these tumours and the spectrum of magnetic resonance imaging (MRI) and computed tomography (CT) appearances.

MATERIALS AND METHODS

The MRI and CT findings of 27 histopathologically proven SCLs were evaluated retrospectively. Imaging features evaluated included margins, percentage visible fat, MRI signal characteristics, oedema, and contrast enhancement patterns.

RESULTS

Patient ages ranged from 18 to 80 years with an average age of 56.5 years. Men were affected twice as frequently as women (M=18, F=9). SCLs ranged in size from 2 to 10 cm, with an average greatest dimension of 5.5 cm. Five lesions (19%) contained no visible fat on CT or MRI, and the leading differential diagnosis of high-grade soft-tissue sarcoma diagnosis was suggested by referring surgeons. Five lesions (19%) had <50% fatty areas, nine lesions (52%) demonstrated >50% but <90% fat at MRI or CT. Only three of 25 lesions (12%) had an appearance of a typical lipoma on unenhanced MRI sequences. All SCLs that were imaged with contrast medium (n = 18) demonstrated some degree of enhancement, with eight (44%) showing marked enhancement, four (22%) showing moderate, and six (33%) minimal enhancement.

CONCLUSION

SCLs have considerably variable imaging appearances and may have minimal or no visible fat at MRI or CT. Imaging features may make it difficult to distinguish this benign tumour from a potentially higher-grade malignant tumour.

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.

Mesenchymal Neoplasms of the Genitourinary System: A Selected Review with Recent Advances in Clinical, Diagnostic, and Molecular Findings

Mesenchymal neoplasms of the genitourinary (GU) tract often pose considerable diagnostic challenges due to their wide morphologic spectrum, relative rarity, and unexpected incidence at GU sites. Soft tissue tumors arise throughout the GU tract, whether from adventitia surrounding or connective tissues within the kidneys, urinary bladder, and male and female genital organs. This selected article focuses on a subset of these lesions, ranging from benign to malignant and encompassing a range of patterns of mesenchymal differentiation, where recent scholarship has lent greater insight into their clinical, molecular, or diagnostic features.

Cytogenetics of Spindle Cell/Pleomorphic Lipomas: Karyotyping and FISH Analysis of 31 Tumors

BACKGROUND

Spindle cell/pleomorphic lipomas are benign tumors. Here, we present our cytogenetic data on 31 such tumors.

MATERIALS AND METHODS

G-banding chromosome analysis and (in selected cases) fluorescence in situ hybridization (FISH) using probes for FOXO1, RB1, and HMGA2 were performed.

RESULTS

Rearrangements of chromosome 13 were found in 58% of tumors. Chromosomes 6, 1, 12, and 11 were also involved in 42%, 26%, 26%, and 23% of tumors, respectively. FISH analysis showed heterozygous deletion of RB1 in seven samples with chromosome 13 aberrations. In four of them, FOXO1 was also deleted. In two tumors with 12q15 rearrangements, FISH confirmed that HMGA2 was targeted.

CONCLUSION

Structural rearrangements of 13q or losses of an entire chromosome 13 are the most common cytogenetic aberrations in spindle cell/pleomorphic lipomas. However, cytogenetic variation exists similarly to what is found in other lipomas, suggesting that various pathways may be responsible for tumorigenesis.

Immunohistochemical differentiation between spindle cell lipoma and neurofibroma of oral cavity using CD34 and SOX10

Spindle cell lipoma (SCL), also called as pleomorphic adenoma, is a rare variant of lipoma histopathologically characterized by an admixture of mature fat cells with spindle cells and occasionally mast cells with myxoid connective tissue stroma and thick bends of birefringent collagen. Although buccal mucosa is the most common location for oral lipomas, for SCL, it is an exceedingly rare location. We report a case of an asymptomatic swelling of buccal mucosa that simulated the features of neurofibroma on histopathological examination, and the final diagnosis of SCL was made on the basis of immunohistochemical features. This is the first documentation of oral SCL using SOX10 to achieve the final diagnosis.

Intramuscular (Subfascial) Vascular Spindle Cell Lipoma. A Case Report

Spindle cell lipoma is a distinct type of lipoma characterized by replacement of mature fat by collagen forming spindle cells. It is a benign lesion occurring chiefly in males older than 45 years and affects the subcutaneous tissues in the regions of the shoulder and posterior neck. Deep-seated (intramuscular) spindle cell lipomas are probably uncommon tumors and to date only two cases have been reported in the literature. A new case of a vascular variant of spindle cell lipoma in an intramuscular (subfascial) location is presented and the differential diagnosis is discussed.

Tumours composed of fat are no longer a simple diagnosis: an overview of fatty tumours with a spindle cell component

This is a review of the morphological spectrum of fatty tumours containing a component of spindle cells, highlighting the immunohistochemical and cytogenetic workup that is now mandatory for accurate diagnosis, with the goal of providing a practical approach for practising surgical pathologists. There have been significant advances in recent years in classifying and understanding the pathogenesis of fatty tumours with spindle cells, based on the correlation of histological, immunohistochemical and cytogenetic/molecular findings. In spite of this, morphological diagnosis and accurate classification of fatty tumours with spindle cells can be challenging to diagnostic pathologists. A group of three lesions: spindle cell lipoma, mammary-type myofibroblastoma and cellular angiofibroma share morphological features and are united by retinoblastoma protein (pRb) loss. Closely allied to these lesions, especially spindle cell lipoma is the newly designated atypical spindle cell lipomatous tumour, which shares morphological, immunohistochemical and cytogenetic features with the trio of tumours lacking nuclear pRb. All of these lesions lack MDM2 and CDK4 amplification as well and separation is based on clinical features, principally location. Atypical lipomatous tumour or well-differentiated liposarcoma shows retention of pRb but overexpression and amplification of MDM2. Fatty tumours with spindle cells need to be extensively sampled, with careful attention paid to cellular atypia and location, and they need to have immunohistochemical workup with pRb, MDM2, desmin, CD34 and p16. In addition, cytogenetic analysis for MDM2 and CDK4 amplification has become crucial for the proper identification of these lesions.

Cytohistological Features of Spindle Cell Lipoma- A Case Report with Differential Diagnosis

Spindle Cell Lipoma (SCL) is an uncommon benign tumour of adipose tissue that is usually superficially located in the neck, back and shoulder region. Although it has characteristic histological features it can pose a diagnostic dilemma on cytology. It presents with a mixture of spindle cells, adipocytes, collagen fibres and a myxoid matrix in varying proportions sometimes with mild pleomorphism. Hence, it can be mistaken for other spindle cell, adipose and myxoid tumours which can be benign or malignant. We present a case of SCL of the back in a 47-year-old male, who presented with a slow growing lesion. Fine Needle Aspiration Cytology (FNAC) showed the characteristic cytological features described above and a diagnosis could be given after clinical correlation. We report this case as the cytology of this uncommon tumour has been described in relatively few cases and a correct pre-operative diagnosis will aid in proper management of this tumour.

Spindle Cell Lipomas Arising at Atypical Locations

OBJECTIVES

Spindle cell lipomas (SCLs) are benign lipomatous neoplasms that classically arise in the posterior neck, upper back, and shoulders of older male patients. We sought to characterize the occurrence of this entity at nonclassic sites.

METHODS

All cases of SCL arising at atypical sites were retrieved from our archives.

RESULTS

Of 439 total cases of SCL, 57 arose at atypical locations in 32 men and 25 women (age range, 27-79 years). The tumor sites included leg (n = 23), buttock/perineum/inguinal (n = 10), forearm (n = 9), finger (n = 9), foot (n = 2), toe (n = 2), hand (n = 1), and flank (n = 1). CD34 was positive staining in all cases tested (52/52), while desmin was negative in most tumors (48/50). Thirty-eight of 38 cases tested exhibited loss of Rb expression. No cases showed CPM/MDM2 amplification (0/48). No local recurrences have been reported (n = 39).

CONCLUSIONS

SCLs may arise in the trunk, lower extremities, and distal upper extremities. While most SCLs arising in classic sites occur in male patients, there is a relatively equal sex distribution in tumors at atypical sites. Pathologists should be aware that SCLs arise at atypical locations to avoid misclassification as other lipomatous neoplasms, including atypical lipomatous tumor.

Oral Spindle Cell Lipoma in a Rare Location: A Differential Diagnosis

BACKGROUND

Spindle cell lipoma (SCL) is an uncommon and histologically distinct variant of lipoma. It usually occurs as a solitary, subcutaneous, and well-circumscribed lesion in the posterior neck, shoulders, and back of older men. SCL of the oral cavity is rare. We present the clinical-pathologic features of the third case of SCL located on the hard palate and discuss the histological differential diagnosis with other fusiform neoplasms.

CASE REPORT

A 56-year-old man was evaluated for an asymptomatic swelling on the right side of the hard palate. The intraoral examination showed a 25×20 mm sessile and circumscribed tumor, underlying an apparently healthy mucosa of normal color. The lesion revealed a floating consistency during palpation. Excisional biopsy was carried out based on a clinical diagnosis of lipoma or a benign minor salivary gland tumor. The histopathology demonstrated a well-circumscribed but unencapsulated proliferation of bland spindle cells admixed with mature adipocytes in a collagenous/myxoid stroma. The spindle cells were uniform, exhibiting elongated nuclei and narrow cytoplasmic processes without atypia. They were positive to CD34 and negative to factor VIII, alpha-smooth muscle actin, S100, cytokeratin, and actin. Mitotic activity was low, as confirmed by Ki-67 immunostaining. No lipoblastic activity was found. The diagnosis of SCL was therefore established.

CONCLUSIONS

Oral spindle cell lipoma is a rare benign lipomatous tumor. The histologic picture shows a range of variations and the observation of morphological features is important to distinguish this lesion from other fusiform tumors. Immunohistochemistry should be helpful in this differentiation.

Spindle cell lipoma with predominant nerve sheath tumor-like areas: A potential diagnostic pitfall on aspiration cytology

Spindle cell lipoma (SCL) is an uncommon variant of lipoma that usually is present in subcutaneous fat of adult men. This tumor has a low rate of local recurrence and no risk of malignant behavior. Although histological features of SCL are well documented, cytological descriptions have been few. We present the case of a 41-year man with a right arm swelling, which on fine-needle aspiration cytology showed adipose tissue fragments, spindle cell areas mimicking benign nerve sheath tumor, and bundles of ropy collagen in a myxoid background, suggesting a diagnosis of SCL. SCL with predominant spindle cell component may mimic benign nerve sheath tumor on aspiration cytology. Subtle cytological features like presence of adipose tissue, ropy collagen, and mast cells help in accurate diagnosis.

Spindle cell lipoma of the soft palate

Intraoral spindle cell lipomas (SCL) are very rare and comprise ranging between 1.4%-9.8% of all intraoral lipomas. To our knowledge, no case of a SCL located on the soft palate has been reported in the English-language literature. A 31-year-old female was admitted with a swelling in her soft palate. On examination, a 3 cm sessile, nontender swelling was observed on her soft palate. After surgical excision, it was diagnosed as a SCL.