Dedifferentiated chordoma: A rare tumor with diagnostic challenge

Chordomas are rare locally invasive malignant bone tumors arising from remnants of embryonic notochord. Dedifferentiated chordoma (DC), a rare subtype, is characterized by the presence of a sarcomatous component in conventional chordoma (CC) which may arise de novo or as a malignant transformation of previously treated chordoma. The presence of dedifferentiation warrants a poor prognosis due to distant metastasis and recurrences. De novo DCs pose a diagnostic challenge especially in small biopsies and at metastatic sites. Here, we report the case of a 45-year-old female presenting with a long history of backache and constipation, finally diagnosed as DC. Radiological as well as histomorphological pictures of the tumor posed diagnostic challenges because they can mimic other tumors occurring in a similar location. We found this case worth reporting as de novo DC is rarely reported in the literature and it has the potential to pose diagnostic as well as therapeutic challenges.

Two Cases of Dedifferentiated Chordoma in the Sacrum

Dedifferentiated chordoma (DC) is defined as a chordoma containing sarcoma components. DC is distinguished from conventional chordoma by the rapidity of tumor growth and the potential for distant metastasis. We report two cases of DC, which are developed in the sacrum. We reviewed the medical records and imaging studies of 2 patients diagnosed with DC and the literature published. In the first case, percutaneous biopsy revealed that it was conventional chordoma in the sacrum. Patient underwent radiation therapy (RT). Six years after the RT, the tumor recurred. Surgical removal was performed and the recurrent tumor was diagnosed as DC in histopathologic examination. In the second case, a patient underwent gross total resection of sacral tumor, which was diagnosed with conventional chordoma. Aggravated tumor was detected after 4 months, and patient underwent reoperation. The second operation revealed the transformation of the tumor into DC. The survival time of the patients after the diagnosis was 10 and 31 months. Dedifferentiated chordoma is a rare and highly aggressive tumor. De novo type exists, but it usually transformed from recurrent chordoma after surgical resection or radiation.

Malignant fibrous histiocytoma in chordoma--immunohistochemical evidence of transformation from chordoma to malignant fibrous histiocytoma

Sarcomatous transformation in chordoma (dedifferentiated chordoma) is a very rare condition and has been emphasized as a distinct entity because of its more aggressive clinical course. Here we describe a case of dedifferentiated chordoma (chordoma associated with malignant fibrous histiocytoma) arising from the sacrococcygeal region of a 55-year-old woman. The results of immunohistochemical stain in the chordoma area were strong positive for cytokeratin, epithelial membrane antigen and S-100 protein. The spindle and giant cells in the transitional areas of chordoma and malignant fibrous histiocytoma were positive for cytokeratin and epithelial membrane antigen in addition to vimentin and alpha-1-antichymotrypsin. The spindle and giant cells in the central area of malignant fibrous histiocytoma were negative for cytokeratin and epithelial membrane antigen, but positive for vimentin and alpha-1-antichymotrypsin. This supports the pathogenesis of sarcomatous transformation from chordoma.

Dedifferentiated Chordoma: Report of a case

Dedifferentiated chordoma is a rare pathologic entity presenting an additional sarcomatous component in otherwise classical chordoma. It has been also emphasized that this neoplasm is classified as a distinct entity because of its different clinical settings and aggressive behavior. Dedifferentiation is a peculiar phenomenon but its histogenesis has remained controversial. A 50-yera-old man developed a huge tumor mass in the retrorectal, presacral area, featured with two histological components. The one was a typical chordoma accounted for approximately 60% of the mass and the other was made up of highly cellular, plemorphic, undifferentiated tumor cells, reminiscent partly to the cells of plemorphic malignant fibrous histiocytoma. Ultrastructural features and immunoreactivity against cytokeratin, S-100 protein and alpha-1-antichymotrypsin in both portions support that histologically different components of this neoplasm derive from the same origin. To our knowledge, this is the first case of dedifferentiated chordoma in Korea.