HISTOPATHOLOGY SECTION - CASE REPORT
Year : 2008 | Volume
: 51 | Issue : 1 | Page : 42--44
Unusual presentation of dedifferentiated liposarcoma as paratesticular mass
A Ghosh1, R Swami1, PK Sen2, S Dwaka2,
1 Department of Pathology, Manipal College of Medical Sciences and Manipal Teaching Hospital, Pokhara, Nepal
2 Department of Surgery, Manipal College of Medical Sciences and Manipal Teaching Hospital, Pokhara, Nepal
Department of Pathology, Manipal College of Medical Sciences and Manipal Teaching Hospital, Pokhara
A 75-year-old male presented with complaint of painless left inguinoscrotal mass slowly increasing in size since 9 years. Clinical impression was malignancy arising in left testis or cord. Initial incisional biopsy was reported as fibromatosis. Later on wide excision of tumor was done and histopathology showed dedifferentiated liposarcoma with areas of fibromatosis.
|How to cite this article:|
Ghosh A, Swami R, Sen P K, Dwaka S. Unusual presentation of dedifferentiated liposarcoma as paratesticular mass.Indian J Pathol Microbiol 2008;51:42-44
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Ghosh A, Swami R, Sen P K, Dwaka S. Unusual presentation of dedifferentiated liposarcoma as paratesticular mass. Indian J Pathol Microbiol [serial online] 2008 [cited 2021 Jun 20 ];51:42-44
Available from: https://www.ijpmonline.org/text.asp?2008/51/1/42/40392
Liposarcoma usually occurs in the deep soft tissues of extremities and in the retroperitoneum. It is the most common type of soft tissue sarcoma accounting for 30% of all mesenchymal tumors. Paratesticular liposarcomas are rare and typically reported as an isolated case or components of larger studies of liposarcomas. Paratesticular well-differentiated liposarcoma has a prolonged clinical course with recurrences in more than half the cases, sometimes late.  There are no metastases and the overall prognosis is good.  Different studies showed that the majority of dedifferentiated liposarcomas presented as de novo lesions, whereas the remainder developed as a late complication of a preexisting well-differentiated liposarcoma. , Commonest sites involved by dedifferentiated liposarcoma are retroperitoneum, extremities, trunk, scrotum/spermatic cord, and also subcutis. , The dedifferentiated liposarcomas, as a subgroup among the malignant fibrous histiocytoma (MFH) like sarcoma, have a better prognosis than pleomorphic sarcomas as a whole. 
A 75-year-old male presented with the complaint of painless left inguinoscrotal swelling slowly increasing in size since 9 years. The size has increased suddenly in last 6 weeks. Clinical examination of the patient revealed two swellings, one in the left groin which was hard in consistency measuring 20 x 12 x 8 cm 3 . Second swelling was palpable in the left scrotum measuring 22 x 14 x 10 cm 3 . It was soft in consistency. The left testis could not be located. The penis was buried in the scrotum and pushed to the opposite side. The right testis and cord were palpable and normal. The computed tomography (CT) scan showed a well-demarcated vascular mass in the left inguinoscrotal area with an atrophic left testis. The left spermatic cord showed increased vascularity. Other routine investigations were within normal limits. Clinical impression was malignant testicular tumor or leiomyosarcoma of the cord [Figure 1],[Figure 2].
Incisional biopsy was done at Manipal teaching hospital and reported as fibromatosis. Subsequently wide excision of the mass was done and sent for histopathology.
On gross, two soft tissue masses close to each other were seen. One was large well encapsulated, lobulated lipomatous mass measuring 20 x 14 x 6 cm 3 with grey-white fibrotic areas in between. Also seen are myxoid areas. Periphery showed normal compressed testicular tissue. The other mass from inguinal area showed well circumscribed, hard fibrotic area measuring 16 x 12 x 9 cm 3 . No areas of hemorrhage or necrosis seen in both the masses [Figure 3].
Microscopic examination from both the masses revealed a tumor mass composed of well-differentiated adipocytes interspersed by areas with spindle cell proliferation. In between lipoblasts are seen. The spindle cell area is mild to moderately cellular. The cells are separated by abundant collagen deposition and show plump nuclei without any mitotic figures. The spindle cells are seen infiltrating the adipose tissue, muscle fibers in the periphery, and reaching almost up to the skin entrapping the skin adnexae. No areas of hemorrhage or necrosis seen. Testis was unremarkable [Figure 4],[Figure 5],[Figure 6].
Dedifferentiated liposarcoma is a rare mixed histologic subtype defined by the association of well-differentiated liposarcoma and a nonlipogenic sarcoma of variable histological grade usually with histologically abrupt transition.  At molecular level, retinoblastoma protein has a major role to play in dedifferentiation and "two-hit mechanism" is involved in the altered retinoblastoma protein expression in dedifferentiated liposarcoma.  The dedifferentiated component may already be present at the time of original excision but is much more commonly seen in the recurrent or metastatic foci.  In different studies, however, the majority of dedifferentiation occurred in de novo lesions. , The interval between the primary appearance of the tumor and dedifferentiation varies greatly and in most cases exceeds 5 years.  The dedifferentiation is not a site-specific phenomenon but is more likely a time dependent phenomenon.  The majority of dedifferentiated liposarcomas commonly display high-grade areas resembling malignant fibrous histocytoma or high-grade fibrosarcoma whereas minority shows low-grade areas resembling fibromatosis or well-differentiated fibrosarcoma.  It may show other forms of dedifferentiation including osteosarcoma, leiomyosarcoma, or even rhabdomyosarcoma. , According to WHO, low-grade dedifferentiated liposarcoma is defined as bland spindle cells with a fascicular pattern with cellularity intermediate between well-differentiated sclerosing liposarcoma and usual high-grade areas. The behavior of dedifferentiated liposarcoma as a whole is that of a high-grade sarcoma.  Good prognosis in de novo dedifferentiated liposarcomas seems unrelated to the extent, grade, or morphologic pattern of dedifferentiation. , However, high mitotic activity in the dedifferentiated component was associated with more aggressive clinical course.  The prognosis of liposarcomas with dedifferentiated component of entirely low grade was more similar to traditional liposarcoma than to that of well-differentiated liposarcoma.  However, it is suggested that low-grade differentiation may represent a precursor lesion of high-grade differentiation. 
Paratesticular well-differentiated liposarcoma can develop into either low-grade or high-grade dedifferented liposarcoma over a variable period of time. Prognosis is unrelated to the grade or extent but is related with mitotic activity of the dedifferentiated area.
|1||Montgomery, E, Fisher, C. Paratesticular liposarcoma: a clinicopathologic study. Am J Surg Pathol 2003;27:40-7|
|2||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.|
|3||McCormick D, Mentzel T, Beham A, Fletcher CD. Dedifferentiated liposarcoma. Clinicopathologic analysis of 32 cases suggesting a better prognostic subgroup among pleomorphic sarcomas. Am J Surg Pathol 1994;18:1213-23.|
|4||Takahira T, Oda Y, Tamiya S, Yamamoto H, Kobayashi C, Izumi T, et al . Alterations of the RB1 gene in dedifferentiated liposarcoma. Mod Pathol 2005;18:1461-70.|
|5||Rosai J. Soft tissues. In : Rosai and Ackerman's surgical pathology. Rosai J, editor. Vol. 2. 9 th ed. New Delhi: Mosby; 2004. p. 2283-5.|
|6||Weiss SW, Rao VK. Well-differentiated liposarcoma (atypical lipoma) of deep soft tissue of the extremities, retroperitoneum, and miscellaneous sites. A follow-up study of 92 cases with analysis of the incidence of "dedifferentiation". Am J Surg Pathol 1992;16:1051-8.|
|7||Tallini G, Erlandson RA, Brennan MF, Woodruff JM. Divergent myosarcomatous differentiation in retroperitoneal liposarcoma. Am J Surg Pathol 1993;17:546-56.|