Year : 2010 | Volume
: 53 | Issue : 3 | Page : 525--528
Mediastinal liposarcoma of mixed type in childhood: A report of a case with unusual histologic features
KD Anand Rajan1, Kiran Chikkanahalli Subbarao2, Sandeep Agarwala3, Siddhartha Datta Gupta2,
1 Wilmer Eye Institute at the Johns Hopkins Hospital, Baltimore, MD 21287-9248, USA
2 Department of Pathology, Teaching Block, I Floor, All India Institute of Medical Sciences, New Delhi, India
3 Department of Pediatric Surgery, Teaching Block, V Floor, All India Institute of Medical Sciences, New Delhi, India
K D Anand Rajan
Maumenee 417 600 N Wolfe St, Wilmer Eye Institute at the Johns Hopkins Hospital, Baltimore
We hereby report the occurrence of mediastinal liposarcoma in a 11-year-old female child. Dyspnea and wheezing of long-standing duration were the presenting complaints and a preoperative biopsy failed to yield the diagnosis. Histologic examination revealed heterogeneous areas with well-differentiated liposarcoma-like areas, areas resembling myxoid liposarcoma, and areas of dedifferentiation. Osteosarcomatous foci and whorled areas reminiscent of meningioma were identified in the dedifferentiated areas. Liposarcomas in the mediastinum are extremely rare tumors of childhood and the present case showed unusual histologic features. Complete surgical excision with clear surgical margins remains the primary modality of treatment, although chemotherapy and radiotherapy have been tried.
|How to cite this article:|
Anand Rajan K D, Subbarao KC, Agarwala S, Gupta SD. Mediastinal liposarcoma of mixed type in childhood: A report of a case with unusual histologic features.Indian J Pathol Microbiol 2010;53:525-528
|How to cite this URL:|
Anand Rajan K D, Subbarao KC, Agarwala S, Gupta SD. Mediastinal liposarcoma of mixed type in childhood: A report of a case with unusual histologic features. Indian J Pathol Microbiol [serial online] 2010 [cited 2023 Sep 29 ];53:525-528
Available from: https://www.ijpmonline.org/text.asp?2010/53/3/525/68297
Liposarcomas are mesenchymal malignant tumors of adipocytic differentiation. Bound together only by the occurrence of the characteristic lipoblast, this diverse group of tumors, accounting for an impressively high proportion of sarcomas, comprise widely differing entities with varied histopathologic appearances, cytogenetic aberrations and clinical behavior. They occur characteristically in deep soft tissues, such as the retroperitoneum, but the mediastinum is an uncommon site for liposarcomas, in children and adults alike. It follows that the mediastinal liposarcoma of childhood, unequivocally differentiated from lipoblastoma, is a rare entity. Twelve cases are reported in the literature in children younger than 15 years, and of these, 7 cases as part of a series of cases, which lack specific photomicrographic evidence. We report a case of mediastinal liposarcoma in childhood and illustrate the distinctive histopathologic features encountered.
A 11-year-old girl presented with complaints of cough, dyspnea, and fever for 5 months. She was previously treated as a case of bronchial asthma and for pulmonary tuberculosis presumptively and had received therapy with antitubercular agents for 4 months, with no respite. Physical examination revealed bilateral normal air entry with wheezing and dullness over the upper zone of the right lung was evident on percussion. A chest X-ray film showed opacification of the right upper- and mid hemithorax. Computed tomography (CT) showed a large heterogeneous mediastinal mass involving the right posterior and middle mediastinum with well-defined lateral margins within the right lung and indistinct medial margins within the mediastinum. The tumor abutted the right posterior chest wall-the underlying ribs, however, appeared normal. The mass showed coarse chunky calcification, large fatty and soft tissue components, and enhancing septae within [Figure 1]. The abdomen and pelvis did not reveal any abnormalities. Serum alpha-fetoprotein levels were not elevated (2.7 ng/mL). A CT-guided core biopsy was performed, but it revealed fragments of adipose tissue only and a clinical diagnosis of mediastinal teratoma was offered. The patient underwent right posterolateral thoracotomy and excision of the tumor. Operatively, the mass was found adherent to the esophagus. Bony spicules were felt on the surface of the tumor. A complete resection of the tumor was carried out and the patient remains clinically well to date.
Gross and Microscopic Features
Grossly, the tumor measured 31 Χ 18 Χ 12 cm. It was well circumscribed and partially encapsulated. Serial sections showed lobulated, myxoid, and light yellow areas. No hair, tooth, or cystic areas could be identified. Firm areas were identified with interspersed soft areas, occasional foci of calcification and irregular bony spicules were also palpable. Microscopic examination revealed areas with varying degrees of adipose differentiation-large areas showed well-differentiated mature adipose tissue-like areas [Figure 2]a, other areas were composed of dense fibrous tissue with only occasional scattered fatty areas [Figure 2]b. A mosaic pattern was seen with islands of well-differentiated areas found present with intervening areas composed of high-grade spindle cells with pleomorphic nuclei and eosinophilic cytoplasm. Areas with a high cellularity composed entirely of small spindle cells were recognized; a meningioma-like whorled pattern was seen in these dedifferentiated zones [Figure 2]c. Areas resembling myxoid liposarcoma-with a prominent myxoid matrix and a distinctive plexiform capillary vascular network were also present as well [Figure 2]d. The portions of the tumor, which were bony-hard on palpation, were found to exhibit irregular bony lamellae with scattered atypical tumor cells [Figure 2]e. Characteristic lipoblasts-pleomorphic hyperchromatic giant cells with multiple clear vacuoles indenting a centrally placed nucleus around its circumference were found scattered throughout the tumor [Figure 2]f. No epithelial elements or thymic tissue were identified on extensive sampling.
Liposarcomas are among the most common sarcomas of adulthood, accounting for up to 16% of all sarcomas. They are, however, a rare tumor in childhood. In a 1984 review of 2500 cases from the files of the AFIP coded as liposarcoma, 17 cases were found to occur in children and none of these were found to occur in the mediastinum.  Castleberry and colleagues reviewed the literature from 1858 to 1982 and found 56 children to have been reported with liposarcoma, irrespective of site. They excluded 19 of these cases from their final review because of suboptimal clinical and pathologic data or because the descriptions did not concur with Enzinger and Winslow's criteria for categorization as liposarcoma. Of the remaining 37 cases, 4 occurred in the mediastinum. Schweitzer and Aguam, in their extensive review of mediastinal liposarcomas from 1916 onward, identified 2 patients who were in fact 18 years of age at diagnosis.  The liposarcoma of the mediastinum in childhood is therefore, an extremely rare tumor-only 18 cases have been reported so far in the literature. Many of the reports do not include detailed histopathologic data; of the 10 cases where a complete pathologic diagnosis is available, 2 cases showed adipocytic differentiation with a myxoid stroma, 4 cases were myxoid liposarcoma, 1 case was well-differentiated liposarcoma - mixed type. The follow-up time of available data ranges from 9 months to 4 years. Of the cases with operative data available, 6 cases occurred in the posterior mediastinum and the remaining in the anterior. The patients presented characteristically with cough or wheezing of long-standing duration, occurring due to the impingement of lung parenchyma by the slow-growing tumor. Vascular compressive symptoms were observed in tumors with a predominant superior mediastinal component.  Radiologically, varying soft tissue densities and areas of calcification corresponding to the heterogeneity in cellular differentiation may be present and thus a preoperative biopsy diagnosis may be essential. If the sampled areas in the biopsy consist of well-differentiated tumor, reaching an accurate diagnosis may prove deceptively difficult,  as it was in the present case. The details of the cases are presented in [Table 1].
About 5% of liposarcomas defy straightforward categorization and are classified as liposarcoma of mixed type. The prognosis of adequately excised liposarcomas depends principally on the histologic tumor subtype, so in cases such as the present one the prognostic information the tumor subtype can provide is less apparent. Dedifferentiated liposarcomas are known to exhibit unusual histologic patterns and divergent differentiation. In addition to dedifferentiated liposarcoma, which showed meningioma-like areas and osteosarcomatous foci, the present case showed areas of myxoid liposarcoma as well. Most reported cases of mixed liposarcoma describe the presence of 2 histologic patterns. , The case reported by Plukker and colleagues  showed myxoid and pleomorphic components. Another issue that needs to be addressed is the differentiation of liposarcoma from lipoblastoma, especially in children. The present case displayed areas resembling well-differentiated liposarcoma and myxoid liposarcoma, features which can both be seen in liposarcoma and lipoblastoma. But the presence of large areas of dedifferentiation that showed divergent histologic differentiation and the presence of unequivocal pleomorphic multilobated hyperchromatic lipoblasts all substantiate the diagnosis of liposarcoma.
Complete surgical excision with satisfactory margin clearance is the primary modality of treatment for liposarcomas and this remains true for these tumors in the mediastinum. Of the 12 reported cases with follow-up information, 5 cases showed recurrence, which in all possibility relates to difficulty of obtaining a clear margin during surgery.
In summary, to our knowledge, this is the first case of mediastinal liposarcoma in childhood, which clearly documents the aforesaid wide spectrum of morphologic subtypes within a single tumor.
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