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The following ovarian neoplasms are benign and are included in the differential diagnosis of ovarian enlargement. Dermoid cystic teratomas are the most common benign ovarian neoplasm.
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Credits: Alan B.P. Ng |
Dermoids make up 25% of all benign ovarian neoplasms. They are 80% of all benign ovarian neoplasms in young women found before the age of 20. The interior contains multiloculated cysts filled with bone, hair, sebum, and or teeth. They are occasionally detected on an x-ray of the abdomen because of the finding of a tooth in the abdomen.
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Credits: Serono Laboratories |
Elements of all 3 germ layers (endoderm. mesoderm and ectoderm) can be found.
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Credits: Alan B.P. Ng |
The most common elements are stratified squamous epithelium and its appendages. Respiratory epithelium is found in 50-75% of the tumors. 10-25% are bilateral, and only 1-3% are malignant. The generally accepted theory for their origin is parthenogenic development. This origin is suggested because these tumors arise along the line of migration of the primordial germ cells at 4-6 weeks from the yolk sack to the primitive gonad. For this reason, these ovarian neoplasms are often classified as germ cell tumors.
Struma ovarii is a specialized form of a mature teratoma with a significant predominance of thyroid tissue or evidence of thyroid hormone activity from the tumor.
Serous cystadenomas comprise 20% of all ovarian neoplasms.
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Credits: Alan B.P. Ng |
Ten percent are bilateral. It is hypothesized that they arise through invaginations of the surface epithelium. They are large, unilocular and contain serous fluid. The epithelium is a single layer of regular cuboidal epithelium, with basal nuclei and rare mitoses.
Mucinous cystadenomas also comprise 20% of all ovarian neoplasms. In women less than 20 years of age, however, they constitute 50% of the benign epithelial neoplasms found. Five percent are bilateral. They are frequently multiloculated 15-30 cm cysts. The cyst has a single layer of tall columnar epithelial cells with mucin containing cytoplasm and basal nuclei.
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Credits: Edward C. Klatt, M.D. |
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Credits: Edward C. Klatt, M.D. |
Because a predominance of endocervical gland type epithelium is noted, a metaplastic surface epithelium is the favored hypothesis for their origin. Pseudomyxoma peritonei is seen in 2-5% of mucinous tumors. This condition is a massive collection of mucinous "slime" that accumulates in the peritoneal cavity. Some have suggested that this peritoneal lesion is an aggressive form of ovarian mucinous carcinoma of low malignant potential.
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Credits: C. Matthew Peterson, M.D. |
Other ovarian neoplasms include:
endometriod,
clear cell or mesonephroid,
Brenner
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Credits: Alan B.P. Ng |
stromal, and cystadenofibromas, and serous adenofibroma (solid variant of cystadenofibroma) tumors.
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Credits: Edward C. Klatt, M.D. |
Evaluation of ovarian enlargement is best accomplished by ultrasound. Occasionally MRI or CT may be helpful if malignant neoplastic disorders are considered. CA 125 can be elevated in ovarian cancer, however benign situations like endometriosis and infection can also elevate this level.