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Year : 1999  |  Volume : 9  |  Issue : 2  |  Page : 65-67
Osteosarcoma arising in a mature cystic teratoma of the ovary : A case report

Department of Imageology, Regional Cancer Centre, Thiruvannanthapuram-695011, India

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Keywords: Osteosarcoma, Teratoma, Ovary

How to cite this article:
Ramachandran K, Sasidharan K, Ittyavirah AK, Krishnakumar AS. Osteosarcoma arising in a mature cystic teratoma of the ovary : A case report. Indian J Radiol Imaging 1999;9:65-7

How to cite this URL:
Ramachandran K, Sasidharan K, Ittyavirah AK, Krishnakumar AS. Osteosarcoma arising in a mature cystic teratoma of the ovary : A case report. Indian J Radiol Imaging [serial online] 1999 [cited 2021 Feb 26];9:65-7. Available from:
We would like to report a case of malignant transformation of an ovarian dermoid into an osteosarcoma, in an elderly woman, presenting with pain and abdominal distension. The imaging features are discussed. A brief review of literature is presented.

   Case Report Top

An eighty-years-old woman - seventh gravida, her last childbirth forty-four years back, was referred to us for abdominal imaging. She was 28 years post-menopausal. The main complaints were progressive distension of the abdomen for the last four months and a vague upper abdominal pain for the last one month. She always had "a large belly" according to her near relatives. There was no history of fever, weight loss or loss of appetite. Ultrasound revealed normal liver, spleen, kidneys, bladder and uterus. A large well-defined mass with a fluid-fluid level and hyperechoic areas with acoustic shadowing was found filling almost the entire pelvis and most of the upper abdomen [Figure - 1]. No free fluid was seen. There were no enlarged lymph nodes in the paraaortic and iliac regions. A provisional diagnosis of ovarian dermoid was made.

Her advanced age and the history of abdominal pain prompted us to consider malignant transformation of the tumor and further investigations were performed. CT study of the abdomen and pelvis with oral and intravenous contrast media revealed a large well-defined cyst with thin walls and a fluid-fluid level, arising in the pelvis and extending above the umbilicus [Figure - 2],[Figure - 3]. The upper half of the cyst showed fat density and the lower half showed irregular hyperdense areas, suggestive of calcification or ossification [Figure - 4]. The wall was irregular in some areas. Ring-shaped hyper densities were seen in the cyst fluid.

Laparotomy revealed a 30.0 x 23.0 x 16.0 cm tumor arising from the left ovary. The uterus, right ovary and tube were normal. The omentum showed hemorrhagic deposits. There was no ascites or lymph node enlargement. Excision of the left ovarian tumour and partial omentectomy were done. The post-operative period was uneventful. The specimen showed multiloculated cysts with sebaceous material and hair. There were lobulated irregular solid areas, firm to hard in consistency. Microscopic examination of the cystic area confirmed the diagnosis of a mature teratoma. The solid areas showed a malignant neoplasm composed of cartilage and osteoid. The neoplasm was highly vascular and showed extensive areas of hemorrhage and necrosis. The omentum showed infiltration by the neoplasm. The diagnosis of a malignant teratoma of the left ovary with a histological picture of osteosarcoma and chondrosarcoma with deposits in the omentum, was made. The woman had early metastatic disease in the abdomen and died a month later.

   Discussion Top

Malignant tumor arising from dermoid cyst of the ovary is very rare and the incidence is approximately 1-2% of all ovarian neoplasms [1],[2]. The average age of patients who present with malignant transformation in an ovarian dermoid is 54 years [2]. Pain is not a significant accompaniment of an ovarian dermoid unless hemorrhage or torsion has occurred. Malignant change is to be suspected in cases presenting with pain; Other features include abdominal swelling constipation, diarrhea, frequency of micturition and dyspareunia [2]. Prognosis of malignant transformation in ovarian dermoid is poor. The commonest malignancy to develop in an ovarian dermoid is squamous cell carcinoma (80%). Adenocarcinoma occurs with less frequency (6.8%) and other epithelial malignancies such as melanoma are even rarer [1]. Sarcoma arising from the ovary is a rarity compared to that of carcinoma. In Peterson's series only 19 of 227 cases [8.4%] were sarcomas [1].

For a primary bone tumor to arise in an ovary the commonest possibility is a malignant transformation in a benign cystic teratoma. The other possibility is osseous or cartilaginous metaplasia [3]. Stamp et al [2] in an analysis of 24 cases with malignant change involving one of the elements of an ovarian dermoid cyst could not find a single case of malignancy arising from the bone elements. Climie et al [1] tabulated the findings in 43 cases of cancer developing in pre-existing benign cystic teratomas of the ovary and reported one case of chondrosarcoma. Toshio et al [4] described three cases of primary osteosarcoma of the ovary including a new case of telangiectatic osteosarcoma of the ovary. Stowe et al [5] and other reports suggested that the origin of these primary bone tumors arising in the ovary was probably a malignant transformation occurring in a pre-existing benign cystic teratoma and added that large portions of the teratoma were taken up by the osteosarcomatous process. Ngwalle presented a case of osteosarcoma arising in a benign dermoid cyst of the ovary and claimed the case as the third documented one in the world literature [6].

On plain radiographs the characteristic diagnostic feature of ovarian dermoid is the presence of tooth, either formed or rudimentary. The high fat content of these tumors renders them relatively radiolucent and this feature also helps in radiographic diagnosis. The US appearance depends on the predominating tissue. Dermoids are usually cystic with septae and solid areas inside, producing a complex appearance on US and CT. Calcification, hair, teeth and mural nodules, are all highly reflective on US. The picture may be so complex that the lesions may be difficult to distinguish from lesions such as bowel pathology, complex hematoma and pelvic abscess. CT demonstration of fat in a mass associated with calcification or tooth is virtually diagnostic of an ovarian dermoid. Fluid-fluid levels or fat-fluid levels may be found [7]. There are only a few reports dealing with the imaging features in cases with malignant transformation of benign cystic teratomas. In a report of two such cases, a single large plug (more than 5 cm) with a cauliflower appearance and an irregular border forming an obtuse angle with the inner wall of the cyst have been described on CT. In addition to other features diagnostic of dermoid, contrast enhancement was noticed in the plug in one of the above cases [8]. Toshio et al [4] could diagnose preoperatively by CT only a "cystic teratoma. We too diagnosed only a cystic teratoma preoperatively. Of all the available imaging modalities, CT is considered the best imaging modality for the diagnosis of benign cystic teratoma of the ovary [8]. It is useful for metastatic work up and can also be used to diagnose the presence of free fluid in the abdomen, pleural effusion, enlarged para-aortic lymph nodes, liver metastases and lung nodules.

   References Top

1.Climie ARW, Health LP. Malignant degeneration of benign cystic teratomas of the ovary. Review of the literature and report of a Chondrosarcoma and carcinoid tumor. Cancer 1968; 22: 824-832.   Back to cited text no. 1    
2.Stamp GWH, Mc Conell EM. Malignancy arising in cystic ovarian teratomas. A report of 24 cases. Br. J Obstet Gynaecol 1983; 90: 67.   Back to cited text no. 2    
3.Russel P, Bannatyne P, Solomon HF. Malignant mullerian and miscellaneous mesenchymal tumors of the ovary [ovarian sarcomas]. In: Malcolm C ed. Gynaecological Oncology, 2 ndsub edition: Churchill Livingstone, 1992: 971-986.   Back to cited text no. 3    
4.Toshio H, Masazumi T, Munetomo E, Ritsuo S. Ovarian sarcoma with histologic features of Telengiectatic osteosarcoma of the bone. Am J Surg Pathol 1988; 12: 567-572.   Back to cited text no. 4    
5.Stowe LM, Watt JY. Osteogenic sarcoma of the ovary. Am J Obstet Gynaecol 1952; 64: 422-426.   Back to cited text no. 5  [PUBMED]  
6.Ngwalle KE, Hirakawa T, Tsuneyoshi M, Enjoji M. Osteosarcoma arising in a benign dermoid cyst of the ovary. Gyenecol Oncol. 1990; 37: 143-147.   Back to cited text no. 6    
7.Paul DR, Paula JM. The female pelvis: Neoplastic and Non-neoplastic masses. In: Arnold CF, Paul DR, Anna SL, Pamela LH [eds] Clinical pelvic imaging. CT, Ultrasound and MRI. Toronto: CV-Mosby, 1990: 195-197.   Back to cited text no. 7    
8.Buy JN, Ghossain MA, Moss AA, et al . Cystic teratoma of the ovary: CT detection. Radiology 1989; 171: 697-701.  Back to cited text no. 8    

Correspondence Address:
Krishnankutty Nair Ramachandran
Department of Imageology, Regional Cancer Centre, Thiruvannanthapuram-695011
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Source of Support: None, Conflict of Interest: None

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[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4]


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