|Year : 2013 | Volume
| Issue : 5 | Page : 114-117
A case of parachordoma on the chest wall and literature review
Jie Zhang1, Hao Wang2, Xinyu Cheng2, Min Wang2, Yue Zhu2
1 Department of Medical Ultrasound and General Surgery, Tianjin Medical University General Hospital, Tianjin 300054, China
2 Tianjin Medical University General Hospital, Tianjin 300054, China
|Date of Web Publication||30-Sep-2013|
Department of Medical Ultrasound, Department of General Surgery, Tianjin Medical University General Hospital, Tianjin 300054
Source of Support: None, Conflict of Interest: None
Parachordoma is an extremely uncommon soft-tissue tumor, which mainly occurs in the deep soft-tissue of the distal parts of the limbs, such as deep fascia, muscle tendon, synovial or soft-tissue closed to the bone. Nevertheless, the literature reports about parachordoma on the thoracic wall were scarce. The clinical and imaging manifestation has a non-specific appearance. In this article, we reported one case of parachordoma of the thoracic wall that we met in clinical works and reviewed the literature.
Keywords: Differential diagnosis, immunohistochemistry, parachordoma, surgical treatment
|How to cite this article:|
Zhang J, Wang H, Cheng X, Wang M, Zhu Y. A case of parachordoma on the chest wall and literature review. J Can Res Ther 2013;9, Suppl S1:114-7
FNx01JIE ZHANG AND HAO WANG CONTRIBUTED EQUALLY TO THIS WORK
| > Introduction|| |
Parachordoma is a kind of soft-tissue tumor whose origin is unknown. Laskowski first described this entity as extra-axial chordoma in 1995,  with a series of 5 cases. In 1977, Dabska reported five new cases and coined the term parachordoma.  So far, the largest published series consists of 101 cases, but the tumor on the thoracic wall was rarely reported. In order to improve the understanding of the tumor, we report one case of parachordoma on the thoracic wall in clinical works and discuss clinicopathologic characteristic, diagnosis and differential diagnosis with literature review.
| > Case Report|| |
A previously healthy, 42-year-old-man presented to the Tianjin Medical University General Hospital with a mass on the right chest wall for 5 years. 5 years ago, the patient noted a right chest wall mass measuring 0.3 cm × 0.2 cm, but she paid more attention to it. The tumor was slowly growing from then on. And now the diameter is about 3 cm × 2 cm located in right posterior axillary line and the eighth rib junction. The tumor is solid and hard to push, with signs of the eighth rib invasion. There is no swelling, no ulceration, no pain and constriction. A routine thoracic roentgenogram was performed, showing that: The bone structure of the eighth rib on the right was unclear and the density of local chest wall soft-tissue became increased and thickened. Bedside ultrasound (BUS): Round soft-tissue density shadow could be seen along the eighth rib body on the right, which was homogeneous. Computed tomography (CT) value was about 44 HU, the outer edge of lesions was smooth and the border with adjacent muscle was clear, the inner edge was close to the eighth rib, the outside of rib showed periosteal proliferation, but no signs of bone destruction [Figure 1]. Whole-body bone imaging had no obvious anomaly. Chest CT: Round mass shadow was visible in the soft-tissue of the chest wall on the right eighth rib and the biggest sectional area was about 3 cm × 2 cm, the border was clear and the adjacent ribs were hyperplasia. Tumors or tumor-like lesions were not excluded [Figure 2]. Complete preoperative examination and did the right eighth rib tumor local excision in general anesthesia on October 25 th , 2012. The neoplasm about 2 cm × 2 cm was seen during intraoperative, invaded the eighth rib and the border was unclear, had complete envelope and the section was fish-meat like and gray. Frozen biopsy was sent during operation and the result showed: Mesenchymal tumor. Gave the resection of the tumor and surrounding soft tissue, with part of the eighth rib. The pathological report: Macroscopic examination: The sample of the mass and part of rib. The size of the mass is about 2 cm × 2 cm. The tumor had already invaded the rib and the borders are unclear. The mass had a clear border and envelope. The section surface is grayish, semitransparent and contained scattered myxoid areas. Low magnification reveals most of the cells are epithelioid cells. The cytoplasm is transparent oracidophilic and it always has vacuole. The stroma reveals hyaline change and chondromyxoid. The immunohistochemical staining of tumor cells showed: Vimentin, S-100, epithelial membrane antigen (EMA) and cytokeratin (+) [CK(+)], but CD31 (−) The final diagnosis was parachordomas of the right chest wall. The repeated chest radiograph 6 days later showed: No visible pleural effusion or aerothorax. The patient got better and discharged.
|Figure 1: BUS: Round soft tissue density shadow could be seen along the eighth rib body on the right, which was homogeneous. Computed tomography value was about 44 HU, the outer edge of lesions was smooth and the border with adjacent muscle was clear, the inner edge was close to the eighth rib, the outside of rib showed periosteal proliferation, but no signs of bone destruction. Whole-body bone imaging had no obvious anomaly|
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|Figure 2: Chest computed tomography: round mass shadow was visible in the soft tissue of chest wall on the right eighth rib and the biggest sectional area was about 3 cm × 2 cm, the border was clear and the adjacent ribs were hyperplasia|
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| > Discussion|| |
Parachordoma is a soft-tissue tumor, which is rare, low grade malignant. It mainly occurs in the deep soft-tissue of the distal parts of the limbs, such as deep fascia, muscle tendon, synovial or soft-tissue closed to the bone, although nares, groin, pelvis and buttock has reported,  Spivach et al. also reported a parachordoma located on the gastric serosa.  In 2003, World Health Organization (WHO) tumor classified parachordoma, mixed tumor of soft-tissue and myoepithelioma as the tumor whose purported origin is unknown. It is attributed to be ectopic rests of notochord,  Schwann cells,  myoepithelial cells  or specialized synovial cells  with no convincing evidence one way or another.
So far, 101-case series has reported an age range of 3-83 with a mean age of 39.  The gender differences of the tumor are not obvious. The location in the 101-case series was distributed as the lower extremity in 41, upper extremity in 35, head and neck in 15 and the body in 10.  Parachordomas are usually painless tumors and are encountered as slow-growing masses. If it occur secondary changes or tumor compression, the patients will arise the signs of pain and body function limitation. The imaging manifestation has a non-specific appearance. 
Macroscopic examination of parachordoma reveals that the tumor has a lobulated or nodular appearance. The tumor has been reported a diameter range of 2-8 cm with a mean diameter of 3.5 cm. It has the envelope and clear borders. The section surface is grayish, semitransparent and contained scattered myxoid areas. If the size of the tumor is very large, it will cause bleeding, necrosis and cystic degeneration. Low magnification reveals that the tumor is divided into different sizes of lobules by fibrous tissue. The tumor cells present short spindle, round and epithelioid. The cytoplasm is transparent or acidophilic and it always has vacuole. The nucleus is hyperchromatic or vacuolated, Mitotic activity is minimal. The tumor cells are arranged in cords, nests or vacuolated in a myxoid matrix [Figure 3]. Parachordoma stain positively for Vim, S-100, EMA, smooth muscle actin, CAM5.2, but negatively for carcinoembryonic antige, Des. But it express CK 8/18 but are negative for other cytokeratins, including CK 1/10, CK 7, CK 20, CK 19 and CK 12-17.  Meanwhile, parachordoma frequently is positive for type IV collagen. In our case, immunohistochemical staining of tumor cells showed: Vimentin, S-100, EMA and CK(+) [Figure 4], [Figure 5], [Figure 6] and [Figure 7], but CD31(−).
|Figure 3: Most of the cells are epithelioid cells. The cytoplasm is transparent or acidophilic and it always has vacuole. The stroma reveals hyaline change and chondromyxoid (H and E, ×100)|
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|Figure 5: Epithelial membrane antigen positivity in tumor cells (×40) (×100)|
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It is important to distinguish parachordoma from conventional chondrosarcoma and extraskeletal myxoid chondrosarcoma because both have significant risks of local recurrence and distant metastases. In contrast, parachordomas are benign tumors that metastases and recurrences are rarely seen. Specifically, (1) chordoma: There are lots of similar manifestation between chordoma and parachordoma, but different characteristics also exist in location, histology and immunohistochemistry. Parachordoma mainly occurs in the deep soft-tissue of the distal parts of the limbs, such as deep fascia, muscle tendon, synovial or soft-tissue closed to the bone. In histology, parachordoma consists of vacuolar cells, spindle epithelial cells and small rounded global cells. Chordoma always located in in the axial skeleton, especially in the sacrococcygeal region, sphenooccipital area or the vertebral column. Meanwhile, chordoma has a lot of vacuolar cells. In addition, the myxoid matrix of parachordoma has the high concentration of hyaluronic acid, alcian blue staining express positive. After it reacts with hyaluronidase, alcian blue staining express negative. But after reacting with hyaluronidase, chordoma stains positively by alcian blue.  In sides of immunohistochemistry, it mainly similar between parachordoma and chordoma, such as S-100, EMA, CAM5.2 positively. However, parachordoma only express CK 8/18, but are negative for other cytokeratins, including CK 1/10, CK 7, CK 20, CK 19 and CK 12-17. In constrast, chordoma express those CK. Moreover, parachordoma frequently is positive for type IV collagen. However, chordoma surrounded by ColIV is rarely seen. (2) Extraskeletal myxoid chondrosarcoma: This tumor always occurs in middle-aged or elderly people. In the meantime, parachordoma mainly occurs in young adults, which mean age of 39. In histology, the former's cells have a lobular or nodular pattern, which divided by fibrous tissue. Most of the nodules are solid, which composed of rounded or short spindle cells. The nuclei are hyperchromatic with inconspicuous nucleoli. The cytoplasm is pale. Extraskeletal myxoid chondrosarcoma does not have vacuolar cells and small rounded global cells like parachordoma. The stroma of the tumor is uniform and mucopolysaccharide of the stroma cannot be digested by hyaluronidase. So after reacting with hyaluronidase, the tumor stains positively by alcian blue.  This method is helpful to distinguish them. In sides of immunohistochemistry, extraskeletal myxoid chondrosarcoma does not have epithelium or differentiation of myoepithelial. However, Des is the only marker, which the tumor constantly expresses. Only a few cases express S-100. Some tumor expresses CK or EMA. Cytogenetics can be used to distinguish them. It has reported that about 75% of extraskeletal myxoid chondrosarcoma has the characteristic chromosomal anomaly of t (9;22) (q22;q12).  This phenomenon does not occur in parachordoma. Now, there are only a few cases reporting the cytogenetics of parachordoma. Folpe et al.  found trisomy 15 and loss of chromosome 1, 16 and 17 in one case with chromosomal studies. Tihy et al. reported a loss of chromosomes 9, 10, 20 and 22 in seven cells, a loss of chromosome 17 in four cells and a structural rearrangement of chromosome 3 [del (3q)] and chromosomes 2 and 4 [t (2p; 4q)] in a recurrent tumor.  Because studies about cytogenetics of parachordoma are rarely, Hence, the characteristic need to be further explored. Furthermore, parachordoma also need to be distinguished with Metastatic mucinous adenocarcinoma, intramuscular myxomas and chondroid parachordoma.
According to the oncology classification of WHO international diseases, parachordomas is the interval tumor that has local invasiveness. Currently, the treatment of parachordomas mainly is expanded surgical resection. The biology behavior of most parachordomas is benign, but it is not rare extremely of metastasis and recurrence. Dabska reported,  the cases of recurrence 2, 7, 12 years later. However, Niezabitowski reported  that one case of recurrence happened 3 months later. It is hard to follow-up the parachordomas for a long time, so it is difficult to statistic average recurrence rate. Satoshit,  Carstens,  Miettinen  from abroad reported that there were three patients died of postoperative metastasis,  so it is possible for parachordomas to occur local recurrence and a few cases appear metastasis after operation and the closely post-operation follow-up should be examined.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]