Lipoleiomyosarcoma of the mediastinum

Lipoleiomyosarcoma Presenting as Massive Retroperitoneal Mass: An Unusual Soft Tissue Tumor of Abdomen and its Review of Literature

Lipoleiomyosarcoma is a malignant tumor of both mesenchymal and smooth muscle origin. Lipoleiomyosarcoma is a very rare type of retroperitoneal sarcoma, which by itself is a rare type of soft tissue sarcoma. Lipoleiomyosarcoma is a very rare subtype of liposarcoma, which is the most common type of retroperitoneal sarcoma. To our best review of available literature, this was the first case of lipoleiomyosarcoma presenting as a massive retroperitoneal mass of size 50 × 50 × 30 cm, managed with multi-visceral R0 resection. The computed tomography of the abdomen showed a massive fat density lesion with internal soft density lesions and internal calcifications. Multivisceral resection was planned and executed and achieved R0 resection. We suggest that lipoleiomyosarcoma should be included in differential diagnosis of retroperitoneal tumors, and multi-visceral R0 resection should be considered as an option for lipoleiomyosarcoma, as these tumors have very good prognosis with R0 resection.

Liposarcomas of the mediastinum

Liposarcoma is a malignant tumor of adipocytic differentiation that rarely arises within the mediastinum. Most of the existing data available comes from scattered case reports and a few small series. The World Health Organization (WHO) recognizes four basic types of liposarcoma: well-differentiated/atypical lipomatous tumor (ALT), dedifferentiated, myxoid and pleomorphic liposarcoma (PLS). All of these liposarcoma subtypes have been recorded to occur within the mediastinum. On morphologic grounds liposarcoma can present a challenge for diagnosis as it can be difficult to distinguish from benign adipocytic neoplasms, or in the case of dedifferentiated liposarcoma (DDLS), from virtually any other type of sarcoma. Molecularly the most common subtypes of liposarcoma are characterized by specific, recurrent genetic alterations involving amplification events of MDM2 and CDK4 in well-differentiated liposarcoma (WDL) and a recurrent t(12;16)(q13;p11) in myxoid liposarcoma (MLS). MDM2 and CDK4 amplification can be assessed by immunohistochemistry, fluorescence in situ hybridization, or molecular techniques that evaluate copy number alterations and amplifications such as array based assays and next generation sequencing (NGS). In addition to WDL and MLS, a few additional rare subtypes of liposarcoma may occur in the mediastinum including PLS, myxoid WDL, thymoliposarcoma, and sclerosing high-grade liposarcoma. The present review will focus on the clinicopathologic features of the various histologic types of liposarcoma described in the mediastinum and their differential diagnosis. Data is derived from review of the largest series published in the more recent literature on these tumors.

Retroperitoneal Well-Differentiated Liposarcoma With Uterine-Type Leiomyomatous Differentiation: A First Case Report With Literature Analysis of Soft Tissue Sarcomas With Dual Lipomatous and Low-Grade Smooth Muscle Differentiation

The occurrence of smooth muscle differentiation in a liposarcoma is a very uncommon phenomenon, even in dedifferentiated liposarcomas. In dedifferentiated liposarcomas, the leiomyosarcomatous component frequently displays high-grade cytologic features, increased mitotic activity, and tumor necrosis. Even more unusual are rare reported cases of low-grade smooth muscle differentiation in atypical lipomatous tumors/well-differentiated liposarcomas (WDLS). The current case describes a 39-year-old female with a large retroperitoneal WDLS harboring a well-demarcated mass composed of benign-appearing smooth muscle fascicles completely lacking cytologic atypia and mitotic activity. In conjunction with the immunopositivity for estrogen and progesterone receptors, the morphology of this nodule was highly reminiscent of a uterine-type leiomyoma. Of note, the lipomatous component largely displayed a lipoma-like appearance with only rare foci of mildly atypical spindle cell proliferation among the adipocytes and few fibrous septae harboring atypical stromal cells. Immunohistochemical and fluorescence in situ hybridization studies revealed MDM2 gene amplification in both the lipomatous and leiomyoma-like areas, thus confirming the diagnosis of a WDLS with smooth muscle differentiation. A literature review on the subject of sarcomas with dual adipocytic and low-grade smooth muscle differentiation provided sufficient supporting evidence to categorize the tumor as a WDLS with “leiomyomatous” differentiation. Pathologists should be aware of the occurrence of uterine-type leiomyomatous differentiation in retroperitoneal WDLS to avoid potential diagnostic errors.

Focal Divergent Chondrosarcomatous Differentiation in a Primary Pleomorphic Liposarcoma and Expression of Transforming Growth Factor 3

A rare case of primary pleomorphic liposarcoma of the thigh with a myxoid component, in which divergent differentiation to a well-differentiated chondrosarcoma was focally present, is described. Presence of heterologous elements has mainly been recognized in the context of dedifferentiated liposarcomas. Few cases of benign mesenchymal tissue have also been reported in well-differentiated and myxoid liposarcomas, while divergent sarcomatous differentiation in liposarcomas appears to be also rare in the absence of dedifferentiation. Positive immunostaining of transforming growth factor-n, which seems to play a role in the formation of bone and cartilage, was demonstrated in our case. Review of the existing literature on the subject has been carried out.

Mesenchymal tumours of the mediastinum--part II

This is the second part of a two-part review on soft tissue tumours which may be encountered in the mediastinum. This review is based on the 2013 WHO classification of soft tissue tumours and the 2015 WHO classification of tumours of the lung, pleura, thymus and heart and provides an updated overview of mesenchymal tumours that have been reported in the mediastinum.

Mesenchymal tumours of the mediastinum--part I

The mediastinum is an anatomically defined space in which organs and major blood vessels reside with surrounding soft tissue elements. The thymus is an important organ in the mediastinum, and many of the masses encountered in the mediastinum are related to this organ. Most neoplasms diagnosed in the mediastinum are epithelial tumours (thymomas and thymic carcinomas), lymphomas or germ cell tumours. In contrast, soft tissue tumours of the mediastinum are rare. In 1963, Pachter and Lattes systematically reviewed soft tissue pathology of the mediastinum, covering the hitherto described [2, 226, 227] In this review, based on the 2013 WHO classification of soft tissue tumours and the 2015 WHO classification of tumours of the lung, pleura, thymus and heart, we provide an updated overview of mesenchymal tumours that may be encountered in the mediastinum.

Lipomatous tumors of the anterior mediastinum with muscle differentiation: a clinicopathological and immunohistochemical study of three cases

Three cases of primary lipomatous tumors of the anterior mediastinum with prominent muscle differentiation are presented. The patients were two women and one man between the age of 52 and 68 years. All patients presented with progressive shortness of breath. Radiographically, all patients demonstrated anterior mediastinal tumors which were surgically resected. In two cases, the gross findings were those of circumscribed tumors, while one lesion was described as an ill-defined and unencapsulated neoplasm. Histologically, two cases corresponded to a well-differentiated liposarcoma, while the third was a thymolipoma. Extensive areas of smooth muscle were identified in one of the liposarcomas, while the other contained areas of mature skeletal muscle. The thymolipoma displayed a prominent myoid component. Immunohistochemical studies for muscle markers including smooth muscle actin, desmin, and myoglobin showed positive staining in the corresponding components. Follow-up information showed that one patient with liposarcoma died 60 months after initial diagnosis, while the other two patients remain alive and well 16 and 36 months after diagnosis, respectively. The current cases highlight the spectrum of muscle differentiation that can be seen in adipose tumors of the anterior mediastinum and also emphasize the difficulty that such a diagnosis can pose when confronted with limited mediastinoscopic biopsies.

Liposarcomas of the mediastinum and thorax: a clinicopathologic and molecular cytogenetic study of 24 cases, emphasizing unusual and diverse histologic features

Liposarcoma rarely occurs in the mediastinum, and most reports predate the current genetically based classification system. We report the clinicopathologic and molecular genetic features of a series of thoracic liposarcomas identified over a 60-year period. Twenty-four confirmed cases were reclassified using the most recent World Health Organization classification. Fluorescent in situ hybridization for CPM amplification and/or DDIT3 rearrangement was performed on selected cases. The 24 cases occurred in 13 men and 11 women (mean age, 53 y; range, 15 to 73 y) and arose in all mediastinal compartments. All subtypes were encountered with 8 well-differentiated liposarcomas, 6 dedifferentiated liposarcomas (3 of 6 confirmed CPM+), 7 pleomorphic liposarcomas (2 of 7 confirmed CPM-, 1 of 7 confirmed DDIT3-), 2 myxoid liposarcomas, and 1 unclassifiable liposarcoma (CPM- and DDIT3-). Unusual histologic features included myxoid well-differentiated liposarcoma mimicking myxoid liposarcoma (2 cases), lipoleiomyosarcoma (1 case), dedifferentiated liposarcoma with "meningothelial"-like dedifferentiation, differentiated myxoid liposarcoma mimicking well-differentiated liposarcoma (CPM-), and pleomorphic liposarcoma with epithelioid and myxoid change. Follow-up information was available for 19 patients (mean, 55 mo; range, 8 to 252 mo). Outcome was strongly associated with histologic subtype, with death from disease occurring in 1 of 6 well-differentiated, 1 of 4 dedifferentiated, 5 of 7 pleomorphic, and 2 of 2 myxoid liposarcomas. The mediastinum shows a preponderance of uncommon subtypes and unusual morphologic variants. Correct classification has important implications, with most patients with well-differentiated/dedifferentiated liposarcoma having a protracted clinical course, in contrast to the more rapid disease progression seen in patients with myxoid and pleomorphic liposarcoma.

Dedifferentiated Liposarcomas With Divergent Myosarcomatous Differentiation Developed in the Internal Trunk

Dedifferentiated liposarcoma (DLPS) is one of the most frequent sarcomas of the retroperitoneum and represents most undifferentiated sarcomas of the internal trunk. In about 5% cases, the dedifferentiated component is an heterologous sarcoma such as leiomyosarcoma or rhabdomyosarcoma. We reviewed a series of 65 sarcomas with a myogenic differentiation developed in the internal trunk for which initial diagnoses were leiomyosarcoma (37), rhabdomyosarcoma (6), malignant mesenchymoma (6), and DLPS (16). Immunostainings for MDM2, CDK4, alpha smooth actin, desmin, caldesmon, myogenin, c-kit, and progesterone receptor were performed. In 48 cases, the amplification status of MDM2 and CDK4 could be evaluated with quantitative polymerase chain reaction on paraffin-embedded tissues extracted DNAs. After review of the cases, final diagnoses were leiomyosarcoma (35), rhabdomyosarcomatous (20) or leiomyosarcomatous (7) DLPS, probable DLPS (2), and malignant mesenchymoma (1). DLPS were bigger tumors (median: 18.2 cm) than leiomyosarcomas (median: 12 cm). They had a lower 5-year recurrence-free survival than leiomyosarcomas (45% vs. 71%) but a higher 5-year metastasis-free survival (73% vs. 39%). There was no significant difference in overall survival (57% vs. 34%). Outcome of patients with a DLPS with a myosarcomatous component did not differ from conventional DLPS. In conclusion, most sarcomas with a rhabdomyosarcomatous differentiation occurring in the internal trunk of adults are DLPS. Moreover, DLPS with a myogenic component have a low metastatic potential, similar to conventional DLPS and significantly lower to the metastatic potential of leiomyosarcomas.

A well-differentiated liposarcoma co-existent with leiomyoma

Background. The coexistence of a well-differentiated liposarcoma (atypical lipomatous tumor) and benign smooth muscle component in a single soft tissue neoplasm is extremely rare. Case report. Histologic and immunohistochemical characteristics of tumor, which represented the reccurence of a retroperitoneal atypical lipoma in a 50-year-old female patient are presented in this paper. The tumor represented the recurrence of a retroperitoneal atypical lipoma. Lipomatous component consisted of a mixture of lipoma-like and sclerosing variant of well-differentiated liposarcoma. Characteristically, the heterologous smooth muscle differentiation was manifested as a macroscopically visible nodular growth in the form of a leiomyoma within the adipocytic component. It consisted of intersecting fascicles of spindle cells, which lacked mitoses and significant atypia, and were immunopositive for smooth muscle markers. Conclusion. This case of well-differentiated liposarcoma with benign smooth muscle is the first reported tumor of retroperitoneal localization. It is also the first one to exhibit the heterologous smooth muscle component as a distinct leiomyoma.

Malignant glomus tumor of the lung

Primary malignant glomus tumors of the lung are extremely rare, and to our knowledge, only three cases have been described to date. We report one such case in a 53-year-old man who presented with a persistent dry cough. Chest computed tomography scans demonstrated an irregularly shaped mass in the right lower lobe of the lung. Many small nodules were distributed from the main tumor to the periphery, along with bronchovascular bundles. Right lower lobectomy was performed under the diagnosis of lung tumor. The tumor was located in the proximal portion of the right lower lobe and extended along the pulmonary arteries. Histological examination revealed a sheet-like proliferation of epithelioid glomus cells and fascicles of spindle cells. The presence of increased mitotic activity, tumor necrosis and prominent intravascular invasion suggested malignancy. The tumor cells were immunoreactive for vimentin, calponin, h-caldesmon, and alpha-smooth muscle actin, which indicated definitive smooth muscle differentiation. We believe that this is the fourth reported case of malignant glomus tumor of the lung.

Lipoleiomyosarcoma (well-differentiated liposarcoma with leiomyosarcomatous differentiation): a clinicopathologic study of nine cases including one with dedifferentiation

Leiomyosarcomatous (LMS) differentiation is a rare event in liposarcoma (LPS) and may consist of either well-differentiated liposarcoma (WDL) with an intrinsic smooth muscle component, so-called "lipoleiomyosarcoma," (L-LMS) or dedifferentiated liposarcoma having smooth muscle differentiation in the dedifferentiated zones. The latter are high-grade sarcomas, whereas the behavior of the former group is uncertain. Specifically, it is not clear whether the presence of LMS negatively affects the prognosis. We present our experience with nine cases, the largest to date. The patients (seven male, two female) ranged in age from 42 to 65 years (mean 54 years). The tumors were usually large (2 to >40 cm [mean 17 cm]) tumors in the retroperitoneum (two cases), paratesticular-inguinal region (three cases), mediastinum (one case), lung (one case), abdomen (one case), and popliteal fossa (one case). The nine cases qualified as L-LMS and showed typical WDL with a multifocal, gradual transition into smooth muscle areas. The latter areas accounted for a variable portion of the lesions (range 5-90%) and were of low cellularity, mild to moderate nuclear atypia, and low mitotic activity. These areas seemed to arise from or blend with the smooth muscle in the walls of large vessels within the tumor. One case showed areas of dedifferentiation consisting of actin and desmin-negative, high-grade sarcoma. Follow-up in seven cases (range 26-312 months; mean 119 months) showed multiple local recurrences in seven patients and no metastases. Three patients are currently without evidence of disease (follow-up duration 26-312 months; mean 144 months) and four patients are alive with progressive disease (follow-up duration 60-132 months; mean 99 months). Our study suggests that L-LMS is a dual lineage sarcoma as evidenced by the fact that the smooth muscle component is often multifocal, not necessarily found in close association with the atypical changes in fat, and seemingly originates from atypical ("in situ") changes in the vessel wall. The LMS component, which is typically low grade, does not adversely affect the overall behavior of the tumor, which is similar to that of conventional WDL. LMS in L-LMS should not be misconstrued as evidence of low-grade dedifferentiation, a phenomenon that identifies a more unstable and potentially metastasizing lesion.

Atypical lipomatous tumors with smooth muscle differentiation: report of two cases

Two cases of soft-tissue atypical lipomatous tumors with areas of smooth muscle cell differentiation are presented. The patients were a 72-year-old man (Case 1) and a 62-year-old woman (Case 2); their neoplasms were located in the left inguinal region and on the chest, respectively. The adipocytic component in Case 1 contained cells with nuclear atypism and lipoblasts. Case 2 showed only slight nuclear atypism and lacked any lipoblasts. Smooth muscle fascicles were composed of well-differentiated cells with a few mitoses having none or only a slight atypism. They expressed muscle-specific actin and desmin in both cases. No recurrence was recorded during the follow-up time.