OBGY Radiology

Case 8 :
A 55-year-old female, with history of pelvic mass, presents with loss of weight and abdominal distension. What is the diagnosis?

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Fig 1 

Fig 2 (plain)

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Imaging Findings
Study shows a low-attenuation (with fat values) large mass lesion arising from the right ovary, occupying the pelvis. Another mass is seen in the left ovary, however this is hyperdense and shows dense peripheral enhancement on contrast administration. Sharp enhancement within the left mass lesion is seen as well (enhancement of the plug- Fig 3). A scan of the lower abdomen shows an enhancing hyperdense lesion suggestive of a metastatic lesion (Fig1). Minimal free fluid is seen in the abdomen.

Right ovarian dermoid, with malignant transformation of left ovarian dermoid lesion, with metastasis
(Histopath: squamous cell carcinoma)

Malignant tumor arising from dermoid cyst of the ovary is very rare and the incidence is approximately 1-2% of all ovarian neoplasms. The average age of patients who present with malignant transformation in an ovarian dermoid is 54 years.

Malignant change is to be suspected in cases presenting with pain; other features include abdominal swelling constipation, diarrhoea, frequency of micturition, and dyspareunia. 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 rare. 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.

Imaging Features
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. 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. In addition to other features diagnostic of dermoid, contrast enhancement can be noticed in the dermoid plug.

CT is considered the best imaging modality for the diagnosis of benign cystic teratoma of the ovary. 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.

Dr. Sanjeev Mani, Bandra Holy Family Hospital, Mumbai