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  Table of Contents    
CASE REPORT  
Year : 2013  |  Volume : 56  |  Issue : 4  |  Page : 419-421
Primary subcutaneous mixed-type liposarcoma of the thigh showing three simultaneous dedifferentiations: Report of an unusual case


1 Departments of Pathology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India
2 Department of Pathology, University College of Medical Sciences, New Delhi, India
3 Department of Surgical Oncology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh; Director, Bhopal Memorial Hospital & Research Centre, Karondh, Bhopal; Director Incharge, National Institute of Research on Environmental Health, Kamla Nehru Hospital, Bhopal, India

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Date of Web Publication18-Jan-2014
 

   Abstract 

Liposarcoma most commonly occurs in deep soft tissues of the limb and the retroperitoneum; however, its occurrence in the subcutaneous tissue is rare. Mixed-type liposarcoma (MTL) is the rarest subtype. We herein describe a unique case of MTL with three simultaneous dedifferentiations occurring in subcutaneous tissue of left thigh in a 45-year-old male. We briefly review the pertinent literature and report this case because of extreme rarity.

Keywords: Dedifferentiation, liposarcoma, lower extremity, mixed type liposarcoma, subcutaneous

How to cite this article:
Patne SC, Kumar M, Vishwanath A, Pandey M. Primary subcutaneous mixed-type liposarcoma of the thigh showing three simultaneous dedifferentiations: Report of an unusual case. Indian J Pathol Microbiol 2013;56:419-21

How to cite this URL:
Patne SC, Kumar M, Vishwanath A, Pandey M. Primary subcutaneous mixed-type liposarcoma of the thigh showing three simultaneous dedifferentiations: Report of an unusual case. Indian J Pathol Microbiol [serial online] 2013 [cited 2020 Feb 19];56:419-21. Available from: http://www.ijpmonline.org/text.asp?2013/56/4/419/125358



   Introduction Top


Liposarcoma (LPS) is the malignant mesenchymal tumor containing a variable number of lipoblasts. It is a tumor of adulthood that mostly occurs in the deep soft tissues of the limbs and the retroperitoneum. The occurrence of LPS in the subcutaneous tissue is rare. [1] LPS is currently classified by the World Health Organization into: (a) Well-differentiated LPS/atypical lipomatous tumor, (b) dedifferentiated LPS, (c) myxoid/round cell LPS, (d) pleomorphic LPS, (e) mixed-type LPS. [1] Of these subtypes, the mixed-type LPS (MTL) is the rarest, accounting for 4% of all LPS. [2] The so-called combined or MTL is defined by the presence of more than one morphological sub-type of LPS. Further, dedifferentiation in a MTL is quite uncommon. Our literature review revealed only five previously described cases of dedifferentiated MTL, which are reviewed and compared in [Table 1]. We herein report a unique case of MTL of subcutaneous tissue of the left thigh showing three simultaneous dedifferentiations.
Table 1: Mixed type liposarcomas with dediff erenti ati ons described in the literature

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   Case Report Top


A 45-year-old gentleman presented with a mass over lateral aspect of the left thigh since last 1 year. The mass had grown rapidly in the past 3 months with surface ulceration and intermittent spontaneous bleeding. Local examination showed an ulceroproliferative, soft to firm growth of size 6 × 5 cm. There was no history of trauma. Magnetic resonance imaging (MRI) revealed a heterogenous T2 hyperintense and T1 iso-hypointense lobulated mass lesion in the subcutaneous tissue plane on the lateral aspect of left upper thigh. No invasion of the underlying muscle and bone was seen. The MRI findings were suggestive of soft tissue sarcoma. An X-ray of the chest was normal. Fine needle aspiration cytology of the mass was diagnosed as pleomorphic sarcoma. The preoperative laboratory investigations were within the normal limits. A wide local excision of the tumor with primary closure and skin grafting was done. On gross examination, a multilobular tumor measuring 6 × 5.5 × 5 cm was present in the subcutis. The cut surface was solid grey white firm with bluish translucent and brown areas [Figure 1]. Microscopic examination showed three distinguished sarcomatous components: pleomorphic LPS, dedifferentiated part, and well-differentiated LPS. The three components formed approximately 60%, 30%, and 10% of the tumor area, respectively. The pleomorphic LPS extended from the dermis [Figure 2]a to deep subcutis and showed florid mitoses (mitotic count 40-50/10 HPF), formation of many tumor giant cells resembling high grade sarcoma along with variable numbers of pleomorphic, hyperchromatic, and multivacuolated lipoblasts [Figure 2]b. The presence of hyaline globules was also noted. At places, the tumor cells infiltrated the overlying epidermis. The pleomorphic liposarcomatous area was sharply demarcated from a small area of well-differentiated LPS [Figure 2]c, which was composed of adipocytes with marked variation in size, shape, and nuclear atypia and occasional intracellular hyaline globules [Figure 2]d. The pleomorphic LPS component showed gradual transition into a dedifferentiated zone. The dedifferentiated zone was comprised predominantly of malignant fibrous histiocytoma (MFH)-like area. There were small focus of hemorrhage and necrosis. The MFH-like area merged with the high grade osteo- and chondro-sarcomatous components. The three dedifferentiated components blended freely with each other in a mosaic fashion. Based on these findings, a final diagnosis of mixed-type (pleomorphic and well-differentiated) LPS showing simultaneous dedifferentiations into MFH-like and high-grade osteo-chondrosarcomas was made. All the surgically resected margins including the deep margin were free of tumor infiltration. The patient received postoperative chemotherapy and was kept under regular follow up. However, 15 months after the surgery, the patient developed bilateral pulmonary metastasis with mediastinal lymphadenopathy. A biopsy of the lung lesions showed pleomorphic LPS/MFH-like histology reminiscent of the primary tumor in the left thigh. At the last follow up, the patient was being treated with chemotherapy for the pulmonary metastasis.
Figure 1: Gross photograph of the lesion showing solid lobulated subcutaneous mass showing skin ulceration, grey white, bluish translucent and gritt y areas with a single hemorrhagic area in the deep subcuti s

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Figure 2: (a) Skin lining with area of pleomorphic LPS (H&E, 100×). (b) Area of well-diff erenti ated LPS (left half) and pleomorphic LPS (right half) separated by fi brous septa (H&E, 40×). (c) Multi vacuolated
lipoblast from pleomorphic LPS (H&E, 400×). (d) Well-diff erenti ated LPS showing atypical signet ring forms and a hyaline globule (arrow) (H&E, 400×). (e) Dediff erenti ated MFH with storiform dispositi on of pleomorphic spindle tumor cells (H&E, 200×). (f) Dediff erenti ated components showing high grade chondrosarcoma (left half) blended with osteosarcoma (right half) (H&E, 200×)


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   Discussion Top


We herein described an extremely rare occurrence of MTL of subcutaneous location in left thigh with three simultaneous dedifferentiations. As was noticed in our case, recent rapid growth in a lipomatous tumor is indicative of dedifferentiation. Dedifferentiation is defined by the juxtaposition of a non-lipogenic sarcoma to well-differentiated LPS/atypical lipomatous tumor. [1] Although MFH-like and intermediate to high-grade myxofibrosarcomas are the most common dedifferentiated components, heterologous differentiation occurs in 5-10% cases of dedifferentiated LPS. Most common heterologous element is myosarcoma (leiomyosarcoma/rhabdomyosarcoma), osteosarcomatous element is described in few cases, while chondrosarcoma is the rarest heterologous component. [6] The simultaneous presence of three dedifferentiated components in this case is unique as the reported cases of dedifferentiated LPS usually exhibit dedifferentiation in a single lineage. The most common site of dedifferentiated LPS is retroperitoneum followed by the extremities. However, only 2% of dedifferentiated LPS involve the superficial or subcutaneous site. [7] The presence of dedifferentiated component confers an aggressive biological behavior with a local recurrence rate of 41%, a metastasis rate of 17%, and a disease-related mortality of 28%. [7] Anatomic site is the most important prognostic determinant. Dedifferentiation in retroperitoneum carries a far worse prognosis than those in the accessible soft tissue (e.g., extremities). [7] Nevertheless, dedifferentiated component of the extremity is also capable of metastasis as occurred in our case. Surgical excision is the treatment of choice with the use of chemotherapy in metastatic disease.

 
   References Top

1.Fletcher CD, Unni KK, Meriens F, editor. World Health Organization classification of tumours: Pathology and genetics of soft tissue and bone. Lyon: IARC Press; 2002.  Back to cited text no. 1
    
2.Mentzel T, Fletcher CD. Dedifferentiated myxoid liposarcoma: A clinicopathological study suggesting a closer relationship between myxoid and well-differentiated liposarcoma. Histopathology 1997;30:457-63.  Back to cited text no. 2
    
3.Kato T, Motohara T, Kaneko Y, Shikishima H, Takahashi T, Okushiba S, et al. Case of retroperitoneal dedifferentiated mixed-type liposarcoma: Comparison of proliferative activity in specimens from four operations. J Surg Oncol 1999;72:32-6.  Back to cited text no. 3
    
4.Hasegawa H, Kawakami T, Eda S. Mixed-type liposarcoma of the oral cavity: A case with unusual features and a long survival. J Oral Pathol Med 1999;28:141-4.  Back to cited text no. 4
    
5.Hosaka A, Masaki Y, Yamasaki K, Aoki F, Sugizaki K, Ito E. Retroperitoneal mixed-type liposarcoma showing features of four different liposarcoma subtypes. Am Surg 2008;74:1202-5.  Back to cited text no. 5
    
6.Panoussopoulos D, Theodoropoulos G, Lazaris AC, Papadimitriou K. Focal divergent chondrosarcomatous differentiation in a primary pleomorphic liposarcoma and expression of transforming growth factor beta. Int J Surg Pathol 2004;12:79-85.  Back to cited text no. 6
    
7.Henricks WH, Chu YC, Goldblum JR, Weiss SW. Dedifferentiated liposarcoma: A clinicopathological analysis of 155 cases with a proposal for an expanded definition of dedifferentiation. Am J Surg Pathol 1997;21:271-81.  Back to cited text no. 7
    

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Correspondence Address:
Shashikant C.U Patne
Department of Pathology, Institute of Medical Sciences, Banaras Hindu University, Varanasi - 221 005, Uttar Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0377-4929.125358

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