Osteolipoma of the tongue

Intra-articular osteolipoma of the elbow: A case report and a review of the literature

Introduction

Lipomas are the most common benign mesenchymal tumors. The intra-articular localization is exceptional.We report the first case of an intra-articular osteolipoma at the elbow.

Case report

A 36-year-old patient with no pathological history, presented to the emergency room with a two weeks history of a painless, progressively left elbow swelling in a context of apyrexia.Physical examination revealed a hot, edematous left elbow. The gentle mobilization of the joint was painless. Biologie was normal. Initial radiograph showed a well-defined lobular image. Ultrasound revealed an anechoic intra-articular collection associated to a synovium hyperaemia and the MRI shows an aspect of synovitis. An arthrotomy was done via an internal approach of the elbow. Joint fluid was red. A free ossified intraarticular mass was discovered. Bacteriological samples were sterile. Histological examination concluded to an osteolipoma with no histological signs of malignancy. At the last 3-year follow-up, the patient didn't report any pain or functional discomfort. Elbow mobility was complete, with the absence of recurrences.

Discussion

Osteolipoma is defined as a histological variant of lipoma having undergone bone metaplasia. Allen found 06 cases in a series of 635 lipomas over five years. Pain has not been reported in the literature. In our case the pain was explained by the interposition of the tumoral mass between the articular surfaces. Histological examination confirms the diagnosis and recurrences are rare.

Conclusion

Osteolipoma is an extremely rare entity of mesenchymal tumors whose intra-articular location, although exceptional, does not worsen the prognosis.

Osteolipoma of head and neck - a review

OBJECTIVE

Due to the rarity of osteolipoma, current knowledge and understanding of its' clinical presentation, management, radiological features, histological characteristics, and prognosis are lacking and can present a clinical conundrum to clinicians and histopathologist alike, given wide range of differential diagnoses. This paper aims to compile, analyse and present details to augment the available literature on osteolipoma in the head and neck.

METHODS

A comprehensive literature search on PUBMED/MEDLINE, EMBASE, CINAHL and Science Citation Index, Google scholar and Cochrane database for osteolipoma in head and neck was performed up to the 1st May 2021. Reference lists from the relevant articles were then inspected and cross-referenced and any other pertinent publications were added to the review.

RESULTS

A total of 38 cases were identified from the literature. The commonest sites of involvement within the head and neck region were the oral cavity in 21 (56.8%) patients, followed by the neck in 7 (19.0%) patients. 29 (78.4%) patients presented with soft tissue swelling or mass making it the most common presenting feature. All patients had the tumour excised surgically; of which 18 (48.6%) were excised via transoral approach and 6 (16.2%) via open transcervical approach including 1 lateral pharyngotomy. 12 papers documented long-term follow-ups (median 12 months) with no recurrence. Only 1 regrowth was reported after 5-years.

CONCLUSIONS

Osteolipoma is a rare soft tissue neoplasm which has a wide range differential diagnosis including malignant processes. Recognising this benign tumour through an awareness of presenting sign and symptoms, radiological features and histopathology findings is important for patient reassurance as well as avoiding unnecessary radical treatment.

Parosteal lipoma of the mandible: A case report and review of the literature

Introduction:

Lipomata are soft-tissue mesenchymal neoplasms that are benign in nature and often asymptomatic. Lipomata commonly occur in the body, however, only 1%–5% are identified within the oral cavity, and lipomata with osseous metaplasia account for <1% of all lipomata.

Materials and Methods:

A PubMed literature review designating search terms including “oral” and “parosteal lipoma” or “lipoma with osseous metaplasia” or “ossifying lipoma” or “osseous lipoma” was conducted.

Results:

The literature review identified two previous reports of parosteal localization of lipomata in the mandible and 22 cases of lipomata with osseous metaplasia within the oral cavity.

Conclusions:

With the initial suspicion of a more malevolent diagnosis, this rare entity, with only two other cases identified, is important to consider in the clinician's differential diagnoses.

Ultrasonographic Findings of a Chondrolipoma Arising from the Left Supraclavicular Region: A Case Report

Chondrolipomas, which are lipomas with chondroid metaplasia, are rare benign soft tissue tumors with no relevant epidemiological reports or radiological information. A limited number of lipomas with osteo/chondroid differentiation have been reported in the literature between 1960 and 2008. Moreover, only few studies have described the radiologic findings of chondrolipomas. Herein, we present a case of chrondrolipoma arising from the left supraclavicular region in a 77-year-old female.

Osteolipoma: a review of the literature and a rare case report

OBJECTIVES

Lipomas are the most common benign mesenchymal tumors of soft tissue. According to previous studies, 1-4% of the cases has been observed in the oral cavity. A histological variant of lipoma featuring bone formation is called osteolipoma and has been very rarely observed (less than 1% of the total). In order to make a meaningful addition to this rare knowledge base, our study aims to provide a literature review and to report an additional case of osteolipoma.

METHODS

An electronic search in the PubMed database with the keyword "osteolipoma" was conducted. Among 69 search results, only the cases of osteolipoma located in the "oral cavity" were included in this study. The findings of the previously reported 20 cases (in English) of osteolipoma of the oral cavity were organized in a table along with a new case of osteolipoma located in the mandibular buccal vestibule with radiological and histopathological findings provided by the authors.

RESULTS

Osteolipoma affects both sexes and usually emerges in middle-aged or elderly patients with a long history of slow progression. Different imaging techniques may be utilized in the radiographic evaluation.

CONCLUSION

Differential diagnosis includes a wide range of lesions; therefore, the clinical and radiographic evaluation should be confirmed by histopathological examination. The suggested treatment is complete surgical excision and follow-up, and the prognosis is generally good.

A rare intramuscular osteolipoma: A case report

•

Osteolipomas are rare and usually located in the intraosseous region or adjacent to bone.

•

Osteolipoma with no connection to bony structures is very unusual.

•

CT and MRI are useful for diagnosis but sometimes they are indistinguishable from well-differentiated liposarcomas.

•

Definitive diagnosis of the lesion can easily be done with histopathologic examination and treatment is by surgical excision.

Introduction

Lipomas are frequently presented in adults and account for almost 50% of all soft-tissue tumors. Osteolipomas are rare and usually located in the intraosseous region or adjacent to bone. It is very unusual for osteolipomas with no connection to bony structures. We report a rare intramuscular osteolipoma independent of bone tissue.

Presentation of case

We report a case of a 58-year-old man with painful and progressively enlarging mass in the right lower leg. A plain X-ray and computed tomography (CT) scans revealed a large homogeneous, low-fat density mass containing an oval shape calcification without bone connection. MRI showed a circumscribed mass in the peroneus muscle with a large calcified component. The patient underwent surgical excision of the mass. Histologically, benign osteolipoma was the final diagnosis. No recurrence was observed at six months follow-up.

Discussion

Lipoma is a common benign soft tissue neoplasm but osteolipoma is rare. Most cases osteolipomas are connected with bone. independent of bone tissue has been reported in very few cases. Most of them occurred in the head and neck area. The pathogenesis of osteolipoma is still not clear. Although CT and MRI are useful for differential diagnosis, care should be taken because sometimes they are indistinguishable from well-differentiated liposarcomas. Excisional biopsy is useful for definitive diagnosis.

Conclusion

Although ossifying lipomas are very rare, it is important to keep them in mind when a lesion with adipose tissue in combination with ossification is encountered.

mDixon-based texture analysis of an intraosseous lipoma: a case report and current review for the dental clinician

An intraosseous lipoma is a rare histologic variant of lipoma, accounting for only 0.1% of all primary bone tumors. This may not be the actual incidence because most of these lesions are frequently asymptomatic, but imaging modalities, such as computed tomography or magnetic resonance imaging (MRI) seem to have increased the detection rate. Lipoma occasionally undergoes osseous metaplasia and becomes an osseous lipoma. Although there are numerous papers discussing intraosseous lipoma and some authors have tried to differentiate lipomas from osseous lipomas, there is still a great deal of confusion with regard to characteristic radiologic features and the use of terms. Use of the mDixon sequence in MRI could be an effective, noninvasive method of lesion detection and differential diagnosis. Texture analysis is a useful technique for capturing intratumoral characteristics. We report what is possibly the first use of the mDixon MRI sequence in the measurement of tumoral texture in a case of the extremely rare inferior nasal turbinate intraosseous lipoma in a 58-year-old female. We conclude that mDixon and texture analysis are helpful methods for differentiating intraosseous lipomas from other masses and confirming the benign characteristics of lipoma. Our review of head and neck intraosseous lipoma could be of particular interest to head and neck surgeons and dental clinicians.

Osteolipoma of the buccal mucosa: a case report

Lipomas are benign mesenchymal neoplasms of soft tissue that can be found commonly in any part of the human body. Their presence in the oral mucosa is uncommon, however, with approximately 4% of the cases occurring in the oral cavity. Oral lipomas are likely to have originated from mature adipose tissue and there are several histological variants of lipomas described, which are identified according to the predominant type of tissue in addition to adipose tissue. A rare lipoma variant, known as an osteolipoma or an ossifying lipoma, may occur; however, little has been written this type of lipoma characterized by a classical lipoma with areas of osseous metaplasia. This paper describes a case of an osteolipoma involving the buccal mucosa of an adult patient.

A case of lipoma of parietal peritoneum causing abdominal pain

Lipomas are common benign tumors of mature adipose tissue, enclosed by thin fibrous capsules. They can occur on any part of the body; however, peritoneal lipoma is extremely rare. We encountered a case of a 75-year-old man presenting with intermittent abdominal pain, who had undergone right hemicolectomy due to colon cancer. Abdominal computerized tomography showed a well-defined heterogenous fatty mass measuring 4.5 × 3.5 cm in size, suggesting fat necrosis located in the abdominal wall. Laparotomy showed a very large soft mass of peritoneum. Pathologically, the tumor was diagnosed as lipoma containing fat necrosis located in parietal peritoneum not fixed to any organs, but with small bowel adhesion. Due to its rare etiologic origin and obscure cause of development, we report on a case of lipoma of parietal peritoneum causing abdominal pain.

"Osteolipoma of buccal mucosa: Case report and literature review"

Osteolipoma affecting oral cavity is indeed rare. We hereby report a case of osteolipoma affecting buccal mucosa. A review of literature of osteolipoma of oral cavity, particularly on radiographic/imaging findings was done. Only 16 cases of Osteolipoma of oral cavity are reported in the literature. The radiographic findings of our case, i.e. multiple dense homogenous radio-opaque structures was reported earlier only in one case [out of 16] of osteolipoma of oral cavity.

KEY WORDS

Lipoma, osteolipoma, panoramic radiography, radio-opaque, radiography.

Osteolipoma: a rare tumor in the oral cavity

Osteolipoma is a rarely reported histologic variant of lipoma that exhibits bone formation. To the best of our knowledge, only 13 well-documented case reports of osteolipoma in the oral cavity have been published in the English literature. This study presents the clinical, radiographic, and histologic features of an osteolipoma in the oral cavity and reviews the pertinent literature. The patient was a 29-year-old female, who presented with an 8-month history of a painless, progressively enlarging, well-defined, movable submucosal mass in the left posterior buccal mucosa. The lesion had a hard consistency. Imaging findings revealed a spherical radiopacity with an irregular trabecular pattern. The lesion was excised and the diagnosis of osteolipoma was established. No recurrence was observed after a 5-year follow-up.

Osteolipoma in the glabella: pathogenesis associated with mesenchymal lipoma-derived stem cells

Lipoma is a benign tumor that often arises in the craniomaxillofacial region. Osteolipoma containing bone tissue is very rare and the developmental mechanism is unclear. Mesenchymal stem cells in adipose tissue that have potential to differentiate into fat, bone, cartilage, and vascular components may be involved in the development of osteolipoma, in which adipose and bone tissues coexist. We encountered a patient with osteolipoma that arose in the glabella. We describe the case and the results of an investigation of the presence in lipomas of mesenchymal stem cells with differentiation potential similar to that of normal adipose cells. The patient was a 66-year-old woman. Histopathologically, bone tissue surrounded by fibrous connective tissue was present in the nodular adipose tissue and was diagnosed as osteolipoma. Mesenchymal stem cells were collected by collagenase treatment of lipoma tissue, and their potential to differentiate into fat, bone, and cartilage was shown. On the basis of this study, we suggest that lipoma-derived mesenchymal stem cells are the basis of the pathogenesis of osteolipoma. The conditions that induce differentiation of mesenchymal stem cells into bone remain to be investigated.

Cervical paravertebral osteolipoma: case report and literature review

Lipomas are the most frequent soft tissue tumors. Osteolipomas are a rare variant that can be difficult to diagnose. We report the case of a 66-year-old man consulting with a tumor of 2 years development in the right paravertebral cervical region. Neurologically, the patient had no sign of myelopathy or neurological focality. Magnetic resonance imaging showed a mass with a lipid component and calcifications inside within the right paravertebral musculature with a possible origin in the right C3 posterior root. A computed tomography scan and guided biopsy were performed, revealing hematic material and small bone spicules with no apparent neoplastic element. The tumor was totally removed, including the right C3 posterior branch, and was confirmed to be an osteolipoma on biopsy. The patient remains asymptomatic at 6-month follow-up. The osteolipoma is a benign tumor of soft tissue, characterized by lipoma areas with mature bone tissue differentiation, and even with hematopoietic marrow.

Ossifying parosteal lipoma of the thoracic spine: a case report and review of literature

Introduction

Lipomas are derived from the mesodermal germ layer and are frequently encountered in adults, and account for almost 50% of all soft tissue tumors. Lipomas are classified based on their component tissues and location. A rare subtype, ossifying parosteal lipoma, accounts for 0.3% of all lipomas and occurs with intimate association with the underlying periosteum of the adjacent bone. Though lipomas are considered to be benign tumors, ossifying parosteal lipomas can manifest symptoms due to their location and relationship to nearby skeletal tissues. We herewith report the first known case of ossifying parosteal lipoma presenting in the region of the thoracic spine.

Case presentation

An otherwise healthy adolescent boy presented with a 3-year history of a slowly enlarging painless thoracic mass. A general physical examination was normal, aside from a painless 10 cm mobile, hard mass along the posterior spine in the region of T4 through T6. Musculoskeletal and neurovascular examinations were normal. An ultrasound suggested a solid, cylindrically shaped mass with diffuse ossification. The mass was resected, and the pathology revealed ossifying parosteal lipoma without evidence of malignancy.

Conclusion

Ossifying parosteal lipomas are rare, benign soft tissue tumors that should be added to the differential diagnosis of thoracic masses.

Intramuscular lipoma: a review of the literature

Lipomas are the most common type of soft tissue mesenchymal tumors. They are typically located subcutaneously and consist of mature fatty tissue. When they occur under the enclosing fascia, they are called deep-seated lipomas. Infrequently, lipomas can arise inside the muscle and are called intramuscular lipomas. Intramuscular lipomas have been commonly investigated and categorized in the same group as other deep-seated and superficial lipomatous lesions. Their clinical, histological and imaging characteristics may resemble well-differentiated liposarcomas, further adding to the difficulties in the differential diagnosis. This article summarizes the available literature and describes the typical epidemiological, pathological and clinical features of intramuscular lipomas, as well as delineating their treatment and prognosis.

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.

A large parosteal ossifying lipoma of lower limb encircling the femur

Introduction

Lipoma is a benign soft tissue neoplasm that may contain mesenchymal elements, as a result of metaplastic process. Ossification in benign and malignant soft tissue tumors can also manifest due to metaplastic process.

Case presentation

A 45 year old woman presented with a large thigh mass. The mass was developed one and a half year ago which insidiously increased in size and was associated with movement restriction. Radiological findings revealed soft tissue neoplasm on antero-medial aspect of thigh encircling the femur and displacing adjacent muscles. Fine trabeculations were seen in neoplasm suggestive of ossification. Excision of the mass was performed and histopathology revealed adipocytes with mature bony trabeculae possessing prominent osteoblastic rimming suggestive of ossifying lipoma.

Conclusion

It is important to recognize this variant of lipoma as it is associated with a better clinical outcome in contrast to most of the deep seated soft tissue neoplasms. Secondly it should also be differentiated from myositis ossificans and heterologous differentiation in other soft tissue neoplasms. We suggest an algorithmic approach to the diagnosis of ossifying soft tissue neoplasms histopathologically. Mature bony trabeculae with prominent osteoblastic rimming in a soft tissue lesion are due to a metaplastic process and should not be confused with osteosarcoma.

Parosteal osteochondrolıpoma of the mandıble

Osteochondrolipoma is a rare benign soft tissue neoplasm. It is occasionally considered to be a variant of adipose tissue neoplasm ‘lipoma’ showing multiple differentiation pathways of pluripotent stem cells. As with the lipomas they can be seen at any location and show cartilagenous and osteoid differentiation when located parosteally. We present a case of osteochondrolipoma located at the symphysis of the mandible. To our knowledge, this is the first reported case of an oral osteochondrolipoma associated with parosteal localization.

Lipoma with bone and cartilage components in the left axilla of a middle-aged woman

Lipoma is the most common type of benign soft tissue tumor. However, lipoma containing bone or cartilage is very rare, especially a tumor containing both of these components. We encountered a 59-year-old woman who had a benign lipoma of the infraspinatus muscle that contained both osseous and chondral components. Histopathological examination revealed the presence of chondral and osseous elements mixed with mature adipose tissue. To the best of our knowledge, there has never been a report of benign lipoma containing osteochondral tissue at this location. Therefore, we report the first case of an axillary lipoma with bone and cartilage components.

LEVEL OF EVIDENCE V

This journal requires that authors assign a level of evidence to each article.

Osteolipoma of the oral cavity: a case report

BACKGROUND

Osteolipoma located in the oral cavity and pharyngeal region is rare.

CASE REPORT

The current case presents the clinical-ultrasonographic-radiographic-histopathological features of the diagnosis and management of osteolipoma of the mandibular buccal mucosa.

DISCUSSION

A literature review of the osteolipoma of the oral cavity and pharyngeal region is also presented. In this localization study, 14 well-documented cases could be found in English-language literature, in which the mean age of patients was 50.6 years, and slight predilection for male gender could be identified. The majority of cases appeared in the oral cavity (67 %). The data demonstrated that osteolipoma of the oral cavity and pharyngeal region is an asymptomatic (80 %) lesion without bone attachment (80 %). The size of the lesions ranged from 8 to 90 mm in diameter (mean = 36 mm), with an evolution time ranging from 1 to 35 years (mean = 7.7 years). Similar to the present case, no recurrence could be identified in works which reported on the follow-up period.

Osteolipoma presenting as a submandibular mass: a rare presentation

Osteolipomas are rare tumors, particularly in the head and neck region, in contrast to lipomas which are the most common benign neoplasms in this location. Osseous changes are benign and mainly occur in long-standing lipomas. Despite its rarity, this neoplasm has a characteristic histopathologic appearance with lamellar bony spicules within the mature adipose tissue. Of the 19 cases previously reported in the oropharyngeal area, only two were located in the submandibular region. We report the third case of submandibular osteolipoma, presenting as an asymptomatic mass in a middle-aged man. Our review of head and neck osteolipomas would be of particular interest to pathologists and head and neck surgeons, in order to avoid inappropriate treatment of an otherwise benign lesion.

Osteochondrolipoma of the submandibular region: a case report and review of the literature

Lipoma is an extremely common and ubiquitous benign soft tissue tumor composed of mature adipose tissue, with frequent differentiation towards other mesenchymal elements such as blood vessels, fibrous tissue, or muscle. They are typically slow-growing, encapsulated, superficial or deep, and have a wide range in size depending on their location. The presence of cartilage or bone is very rare, with most reported cases in the head and neck area. We report the case of an osteochondrolipoma of the submandibular region with associated benign bone marrow elements, with a review of the literature and discussion of the differential diagnosis.

Giant chondrolipoma of the tongue in a 14-year-old child with mandibular hypertrophy. Isolated lesion or regional overgrowth syndrome

Chondrolipoma is a rare condition; especially in the oral cavity. The authors described a giant chondrolipoma of the tongue, associated with mandibular and lower lip overgrowth, in a 14-year-old boy. After tumour excision, histopathological examination showed mature cartilage within lobules of mature adipocytes. This is the first case of giant chondrolipoma associated with facial overgrowth. The aetiology and the association with a localized Proteus syndrome are discussed.

Fibroma with osseous metaplasia of external auditory canal in a dog

The present report describes a case of fibroma with osseous metaplasia of the external auditory canal in a 7-year-old male Pomeranian dog. Upon otoscopic examination, the right external auditory canal was almost completely obstructed by a well-circumscribed mass adjacent to the eardrum. The mass was surgically excised. Grossly, it was well demarcated, firm when cut, pink, and measured 0.3 cm x 0.2 cm x 0.7 cm. The cut surface of the mass exhibited a central portion of homogeneously white osseous components surrounded by brown to pink soft tissue. Microscopically, the resected external auditory canal mass mainly consisted of fibroblastic spindle cells showing differentiation to metaplastic osteoblast-like cells. Metaplastic osteoblasts and osteoclasts lining the osteoid bony trabeculae were also observed. Bony trabeculae and spicules were separated by abundant collagen and neoplastic fibroblastic cells. Fibromatous components, irregular formation of woven bone spicules, and the presence of osteoblasts lining bony trabeculae led to a diagnosis of fibroma with osseous metaplasia.

Rare Lipomatous Tumors with Osseous and/or Chondroid Differentiation in the Oral Cavity Report of Two Cases and Review of the Literature

The purpose of this study was to determine the clinicopathological and immunohistochemical features of lipoma/fibrolipoma with rare occasions as osseous and/or chondroid differentiation in the oral cavity. Two cases of the tumors, who presented with a painless, relatively hard mass on the oral mucosa, were studied. These were consisted of a well-circumscribed mass of fatty tissue with chondroid and significant fibrous component intermixed with the lobules of fat cells with chondroid and woven bone component, respectively. Immunohistochemical study revealed that peripheral spindle cells around chondroid tissue stained diffusely for S-100 α & β and Sox-9, though peripheral spindle cells around osteoid tissue only stained for RUNX-2. According to review of the literature, lipoma/fibrolipoma with osseous and/or chondroid differentiation was 18 cases. Also fibrolipoma with osseous and chondroid differentiation is the first to be reported here. These results indicated that the cartilage/bone is produced by differentiation of undifferentiated mesenchymal cells of stroma.

Osteolipoma independent of bone tissue: a case report

Introduction

Lipomas are the most common benign soft tissue tumors and appear in any part of the body. They typically consist of mature adipose tissue. Osteolipoma is an extremely rare histologic variant of lipoma that contains mature lamellar bone within the tumor and osteolipoma independent of bone tissue are very rare. We report a case of histologically confirmed osteolipoma independent of bone located in the thigh.

Case presentation

A 47-year-old male presented with a progressively enlarging, painful mass which approximately 10 cm × 8 cm over the anteromedial aspect of his right thigh. Plain films, Computerized Tomography, Magnetic Resonance Imaging and ultrasound guided needle biopsy were performed. Given the benign imaging characteristics and fine needle aspiration, an excisional biopsy was undertaken. The definitive pathologic diagnosis was intramuscular osteolipoma without evidence of malignancy. No recurrence was observed after 18 months follow up.

Conclusion

Although ossifying lipomas are very rare, it is important to keep them in mind when a lesion with adipose tissue in combination with ossification is encountered.

Lipomas of the oral cavity: clinical and histopathologic study of 41 cases in a Brazilian population

This study evaluated the clinical and histopathologic aspects of 41 cases of oral lipomas diagnosed in a Brazilian population. All records from patients diagnosed with oral lipoma between 1970 and 2008 were reviewed. Histological sections were evaluated by light microscopy. There was a predominance of females (2.4:1), with a peak incidence between the sixth and seventh decade. The buccal mucosa was the most affected site (53.7%), followed by the buccal sulcus (14.6%) and tongue (9.8%). Tumor size ranged from 0.5 to 10 cm and the mean reported duration was 48 months. Histologically, the following variants were identified: lipoma (41.5%), fibrolipoma (34.1%), spindle cell lipoma (9.8%), sialolipoma (9.8%), osteolipoma (2.4%), and chondrolipoma (2.4%). Most tumors were well delimited, irrespective of the variant. Lipomas are rare tumors of the oral cavity. The characterization of new variants, such as sialolipomas, and the identification of histological subtypes in already known variants, such as low-fat and fat-free spindle cell lipomas, highlight the importance for careful microscopic evaluation of these tumors, which might be combined with immunohistochemistry in some cases.

Osteolipoma of the eyelid

A 50-year-old woman presented with a nodular swelling on her right upper eyelid. The tumour was diagnosed as osteolipoma histologically after resection. Osteolipoma is a very rare variant of lipoma and only a few cases affecting the head and neck are reported in literature. To the best of the author's knowledge this is the first reported case of osteolipoma of the eyelid.

Ossifying lipoma of the thigh

Lipomas are common soft-tissue tumours that are usually found in the subcutaneous adipose tissue. Occasionally, they may contain mesenchymal elements other than adipose tissue, including osseous components. These ossifying lipomas are usually located near or within bone, and it is very rare for a lipoma with no connection to bone to contain mature osseous tissue. We describe a case of a symptomatic ossifying intramuscular lipoma of the thigh.

Osteolipoma of the oral and pharyngeal region: report of a case and review of the literature

Osteolipoma is an uncommon phenomenon that rarely occurs in the oral and pharyngeal region. A 68-year-old man presented with a 4-year history of a relatively small painless mass in the right mandibular alveolar mucosa adjacent to the premolar teeth. The lesion was easily excised and histologically confirmed to be an osteolipoma. Ten cases of oral and pharyngeal osteolipoma have appeared in the English literature thus far. In addition to reporting a new case of osteolipoma arising in the oral cavity in this article, the literature is reviewed accordingly.

Osteolipoma of the nasopharynx

Osteolipomas of the head and neck are very rare, and there is no reported case of osteolipoma of the nasopharynx in the literature. Here, we present a case of osteolipoma of the nasopharynx in a 21-year-old male who was referred for a nasopharyngeal mass causing a defect in the left half of the soft palate. The well-demarcated, firm tumor was excised through transnasal endoscopic and transpalatal approaches, and the defect of the soft palate was repaired by a superiorly based pharyngeal flap. Osteolipomas should be kept in mind in the differential diagnosis of nasopharyngeal mass as an extremely rare benign lesion.

Subcutaneous ossifying lipoma: case report and review of the literature

BACKGROUND

Lipomas can undergo a variety of changes, one of which is ossification. Ossifying lipoma (OL), independent of bone tissue, is rare. No case has been reported with this heading in the dermatopathological literature.

CASE REPORT

A 73-year-old woman was referred for a subcutaneous mass on the left scapular region that had been present for more than 22 years.

RESULTS

The lesion was an OL measuring 8 cm and weighing 75 g. Only 25 cases of OL have been described in soft tissues. Including the present report, locations in order of frequency are the head and neck area (11 cases), the limbs (9 cases) and the trunk (6 cases). Average patient age is 50.9 years (range, 17-81 years). History is measured in years (mean, more than 6 years). Average tumor size is 7.1 cm (range, 0.8-20 cm). The adipose component is usually predominant and the mature bone tissue is irregular in distribution. Bone spicules are surrounded by fibrous tissue bands. Chondrous structures are found in 46.2% of tumors. No recurrences have been reported.

CONCLUSIONS

OL is rare but has a characteristic gross, radiological and histological appearance. It has the same prognosis as simple lipoma. Excision is the treatment to be chosen.

Parosteal lipoma of the thigh with cartilaginous and osseous differentiation: an osteochondrolipoma

Lipomas are very common benign soft tissue neoplasms. They are usually slow-growing and may occur anywhere in the body. Mature cartilage and bone arising in a lipoma is a rare event and is mostly associated with a parosteal localization of the neoplasm. We describe a new case of osteochondrolipoma showing not only major adipocytic differentiation but also areas of fibrocytic and cartilaginous cell differentiation and bone formation (both endochondral and membranous). The occurrence of at least 4 distinct directions of mesenchymal cell differentiation within a benign neoplasia underlines the concept of multilineage differentiation of pluripotent mesenchymal stem cells. Such a multidirectional potential was recently well established in vitro in stem cells present in adult adipocytic tissue.

Osteolipoma arising adjacent to the sternoclavicular joint. A case report

A 45-year-old woman presented with one-year history of a mass on her chest. Computed tomography and magnetic resonance imaging demonstrated a tumour near the sternoclavicular joint. The tumour was diagnosed as osteolipoma histologically after resection. Osteolipoma is a rare tumour and this may be the first report of osteolipoma arising adjacent to the sternoclavicular joint.

Divergent differentiation in malignant soft tissue neoplasms: the paradigm of liposarcoma and malignant peripheral nerve sheath tumor

In tumors clonality does not always translate into morphologic uniformity. While most sarcomas exhibit only one line of histologic differentiation, a minority may display a strikingly diverse phenotype in addition to the main lineage. This phenomenon not only presents a diagnostic problem but also raises questions about the commitment of tumor cells toward a specific phenotype. Among sarcomas, malignant peripheral nerve sheath tumor (MPNST) and dedifferentiated liposarcoma are two entities in which divergent differentiation is a relatively frequent event. Diagnostically it is crucial to recognize the "primary" sarcoma in such tumors correctly and distinguish it from the "secondary" divergent elements. The presence of the latter could be the first morphologic clue to a specific sarcoma type. Even though it may be difficult to explain the pathogenesis of divergent differentiation, divergence still illustrates that the phenotype of a tumor cell is not set in stone but can be modulated or switched by a number of factors.

Osteolipoma: a rare lesion in the oral cavity

We present the case of a 65-year-old woman who had a painless mass in the left buccal mucosa. Histology showed a benign osteolipoma.

Intraoral benign mesenchymoma: a report of 10 cases and review of the literature

A benign mesenchymoma is an unencapsulated soft tissue neoplasm composed of 2 or more mature mesenchymal tissues not normally associated with each other, excluding fibrous connective tissue. No single mesenchymal tissue should predominate with respect to the other mesenchymal elements. Ten well-documented examples of intraoral benign mesenchymoma have been reported in the English language literature. The purpose of this report is to document 10 additional cases and to review the clinicopathologic characteristics of this uncommon tumor.