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Книги по МРТ КТ на английском языке / MRI and CT of the Female Pelvis Hamm B., Forstner R..pdf
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CT and MRI in Ovarian Carcinoma

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Fig. 17  Clear cell carcinoma arising in an endometrioma. Transaxial T1-weighted image (a), T2-weighted image (b), and contrast-enhanced fat-saturated (FS) T1-weighted image (c). A typical endometrioma of the right ovary is demonstrated in a and b, showing high signal intensity (SI) on T1weighted image and shading with low SI on the T2-weighted image. Within the posterior wall of the endometrioma, a band-like mural lesion (arrow) with low SI on T1-weighted image (a) and high SI on T2-weighted image (b) is seen. Due to contrast enhancement, it is obscured in c. Contrast enhancement is not found in a clot in endometrioma, but is indicative of a tumor within the endometrial cyst. Hematometra (*)

Clear Cell Carcinomas

Clear cell carcinomas present approximately 5–10% of all ovarian cancers. The relationship with endometriosis is strongest among the ovarian cancers. The tumor may arise within an endometrioma (Fig. 17), or endometriotic implants may be found in relationship to the tumor or ­elsewhere in the pelvis (Lalwani et al. 2011). Hypercalcemia as a paraneoplastic syndrome and thromboembolic complications are more common than in other ovarian cancers (Lorraine et al. 2010). Typical imaging feature is a large thick-­ walled cyst with one or multiple nodules protruding into the mass (Tanaka et al. 2010).

Imaging Findings of Epithelial Ovarian Cancers

On CT and MRI, epithelial ovarian cancers present as complex cystic or multiloculated ovarian lesions. Although differentiation between the subtypes is not reliably possible by imaging, there might be some differential diagnostic clues. Disseminated peritoneal disease is typical of high-grade serous cancers. A large well-­ delineated multilocular mass is suggestive of mucinous cancer. Psammoma bodies, which can only be detected on CT, may be seen in low-grade serous ovarian cancers. Endometriosis is a precursor of endometrioid, and especially of clear cell cancer. The latter appears most commonly as a large unilocular cyst with one or more solid mural nodules (Tanaka et al. 2016). In endometrioid ovarian cancer, endometrial thickening or endometrial cancer may coexist. Details of histological, imaging, and clinical characteristics of the major ovarian cancer subtypes are enlisted in Table 4.

Differential Diagnosis

Benign serous and mucinous cystadenomas are usually entirely cystic and display thin walls and septa. Small papillary projections may also be present in cystadenomas. Metastases, particularly from primary cancer of the appendix or the gastrointestinal tract, can display similar imaging characteristics as ovarian cancer. Calcifications may also be present in metastases of mucinous adenocarcinoma of the colon