Multifocal Giant Retroperitoneal Dedifferentiated Liposarcoma with dual heterologous dedifferentiation– a diagnostic and therapeutic challenge

Prita Pradhan^1*, Urmila Senapati¹, Saroj Ranjan Sahoo², Sabyasachi Parida²

¹Department of Pathology, Kalinga Institute of Medical Sciences, Bhubaneswar, Odisha, India – 751024. ²Department of Surgical Oncology, Kalinga Institute of Medical Sciences, Bhubaneswar, Odisha, India – 751024.

Abstract

Dedifferentiated liposarcoma (DDL) with divergent dedifferentiation is uncommonly reported with variable incidences. Liposarcomas, particularly those manifesting dedifferentiation, occur in the retroperitoneum. They grow into large size, present at very late stages, and can have a poor clinical outcome. Here we present a rare case of recurrent dedifferentiated liposarcoma with dual heterologous differentiation with osteosarcoma and Chondrosarcoma in an elderly male who had initially presented with inguinal hernia. A large mass was occupying the entire abdomen, confirmed on CECT occupying the left side with loss of fat planes with the left kidney and spleen. During exploratory laparotomy, a large retroperitoneal mass occupying the whole abdomen from the left side of the retroperitoneum pushing the left and transverse colon with the mesocolon, the ureter to left side across midline was found, which was excised with the kidney preserved. Grossly multiple large fragments of tumor masses were received, ranging in size from 15 to 40 cm in their most significant dimension and weighing more than 25kgs. Extensive sampling from all the tumor masses was done for histopathology, which revealed well-differentiated liposarcoma having juxtaposed heterologous differentiation into chondrosarcomatous and osteosarcomatous areas. A final diagnosis of recurrent multifocal giant retroperitoneal dedifferentiated liposarcoma with dual heterologous differentiation with osteosarcoma and ChondrosarcomaChondrosarcoma was made. Despite recurrent multifocal tumors, the radiological information, extensive excision, detailed grossing, and histopathology helped in the diagnosis.

Keywords: Sarcoma, Osteoid, ChondrosarcomaChondrosarcoma, Spindle cells

which was excised and sent separately for histopathology.

Grossly five large fragments of encapsulated tumor were received largest of which measuring 40x25x10cm and the smallest measuring 15x15x10cm and weighing about >25kgs (Figure 2a). Serial slices showed a predominantly yellow, homogenous, and solid tumor. However, two of the medium-sized fragments measuring 18cm in the greatest dimension showed firm to hard areas measuring 7cm in the most significant dimension (Figure 2b). Multiple sections from the greasy, firm, and bony areas were studied. Sections from greasy areas showed features of well-differentiated liposarcoma (Figure 3a). Sections from the firm and bony areas showed well-differentiated liposarcoma, having juxtaposed heterologous differentiation into chondrosarcomatous and osteosarcomatous areas(~10% of total tumor) (Figure 3b-3f). Histologic grade was high (grade3), with areas of necrosis amounting to around ~5%. A final diagnosis of recurrent multifocal giant retroperitoneal dedifferentiated liposarcoma with dual heterologous differentiation with osteosarcoma and ChondrosarcomaChondrosarcoma was made. The patient was discharged after post-operative recovery and advised for adjuvant chemotherapy. He refused the same and developed a recurrent mass after a disease-free period of 17 months, measuring 14.6 x 16.9 x 20.5 cm (Figure 4). The recurrent lobulated solid mildly enhancing mass was in the region of the left anterior perinephric space, abutting the renal hilum & renal vessels. The mass further increased to 22 x 35 x 29 cm after 26months of surgery. However, the patient was lost to follow-up.