Squamous cell carcinoma (SCC) of the ovary is extremely rare and usually arises in a mature cystic ovarian teratoma 2. As only parts of the lesion are composed of malignant tissue, it is difficult to diagnose malignant transformation of a teratoma preoperatively, unless invasion into adjacent structures is present.
Malignant transformation in a mature cystic teratoma is relatively rare. When malignant transformation is encountered, it is usually in postmenopausal women and carries a worse prognosis than primary malignant neoplasms of the ovary 1.
The mean age at diagnosis is at ~55 years which is significantly older than the mean age of patients diagnosed with routine mature cystic teratoma (~37.5 years) 4. Thus advanced patient age is useful in raising the suspicion of malignant transformation of a mature cystic teratoma.
The reported incidence of malignant transformation of mature cystic ovarian teratoma is approximately 2% and squamous cell carcinoma is the most common histology (followed by adenocarcinoma and melanoma) 2-3.
Patients present with grossly distended abdomen with pressure effects on the bladder and bowel.
Squamous cell carcinomas arise from the squamous epithelial component of a mature ovarian teratoma. For a general discussion of ovarian teratomas please refer to the parent article: benign mature ovarian teratoma.
Due to the heterogeneity of ovarian teratomas, identification of a malignant component can be difficult preoperative, in the absence of obvious tumour invasion or metastases. In many instances, appearances are indistinguishable from those of a benign mature ovarian teratoma, and their radiographic appearance is discussed separately. A number of features are helpful in increasing suspicion.
A large solid component, especially if irregular or with the suggestion of tissue infiltration is most useful.
Tumour size is also an important factor. Generally, malignant ovarian tumours are larger than benign ovarian tumours. In a study done by Fumitaka Kikkawa et al. 4 the mean size of a benign mature cystic teratoma of the ovary was ~88 mm (92 cases) whereas, squamous cell carcinoma arising from MCT measured ~152 mm (37 cases). These findings suggest that large overall tumour size is useful in differentiating squamous cell carcinoma arising in MCT.
Treatment and prognosis
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