Adnexal Masses (Incidental)

adnexalmasses

Adnexal Masses

• Incidental adnexal masses diagnosed on ultrasound, CT or MRI performed for an unrelated reason have increased in frequency with increased use of cross-sectional imaging 8
• The majority are benign, even in patients with known malignancy or postmenopausal women.8 However it is important to reliably differentiate malignant from benign lesions to avoid delays in treating ovarian cancer and prevent unnecessary interventions in benign lesions
• Risk of ovarian cancer increases with age and post-menopausal status, with 82% of Australian women aged ≥50 years at diagnosis (median age 63 years). 9 A relatively high proportion of ovarian cancer diagnoses occur at an advanced stage due to the non-specific nature of symptoms and lack of effective tests for population-based screening. 5-year survival has only modestly improved from 32% to 43% over the last 20 years. 9 The 5-year survival rate is approximately 93%, 72% and 27% for localised, regional and distant disease respectively 9
• When an incidental adnexal mass is identified, further management will depend on whether the lesion is clearly benign or malignant, or indeterminate. Menstrual status, family history, tumour markers (e.g.CA 125) and development of symptoms also play a major role in determining further investigations
• Changing tumour characteristics on serial imaging, development of symptoms, presence of clearly malignant features on imaging and rising tumour markers are the main indications that should warrant a prompt surgical evaluation
• Watchful waiting with image-based follow-up is the mainstay of incidental adnexal mass management. Even in asymptomatic post-menopausal women where reported prevalence of adnexal cysts varies from 2.5-17%, half resolve on follow-up. If they persist most remain unchanged and risk of malignancy is <1% 5,6

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Ultrasound

• First-line imaging modality in the evaluation of incidental adnexal mass
• Transvaginal is superior to transabdominal approach but both approaches may be needed to adequately visualise the entire lesion. Once cyst size is >7cm, other imaging modalities may also be required
• Use of colour or power Doppler further improves the characterization of suspicious or indeterminate adnexal masses identified on gray-scale ultrasound compared to histological reference standard, 10 but use of Doppler alone without morphology assessment is not recommended 11,12
• 3D ultrasonography (pooled 93.5% sensitivity, 91.5% specificity) is superior to 2D ultrasonography (pooled 85.3% sensitivity, 87.4% specificity) in detecting adnexal lesions 12-14
• Several ultrasound-based morphology scoring systems to differentiate benign versus malignant adnexal lesions have been developed from a symptomatic and asymptomatic study population; the International Ovarian Tumour Analysis (IOTA) prediction models (LR1, LR2, simple rules) are the most widely validated. 1,12,15 Other scoring systems based on a combination of ultrasound, clinical and biochemical indices (e.g. risk of malignancy index, RMI) have not proven superior. 12,16 External validation in the same cohort found IOTA prediction models more sensitive than the RMI and randomised controlled trials are underway to see if its use can reduce unnecessary surgical intervention 17,18
• The IOTA simple rules (applicable to 76% of tumours), with subjective assessment by experienced examiners when rules did not apply, have an approximate 90-92% sensitivity and 90-93% specificity in differentiating malignant from benign lesions 1,2
• A consensus statement by the Society of Radiologists in Ultrasound on adnexal masses in asymptomatic non-pregnant women recognized the following six benign cystic lesions based on specific characteristics found on ultrasound 7
• Simple adnexal cysts
• Haemorrhagic cysts
• Endometriomas
• Dermoid cysts
• Hydrosalpinx
• Peritoneal inclusion cysts
• Compared to histology of surgically removed adnexal masses, a specific diagnosis based on ultrasound was possible in 84% of cases in one prospective study, with specificity and sensitivity for common benign cysts ranging from 94-100% and 77-86% respectively 19
• Lesions not showing the characteristics of the above benign lesions but without any malignant features were classified as ‘indeterminate cysts’ which were further classified based on their likelihood of being benign or malignant. Further evaluation of indeterminate cysts depends mainly on patient’s menopausal status 7
• Features suggestive of malignancy on ultrasound
• Multiple, thick (≥3mm) or branching septations with or without vascularity
• Solid nodules with vascularity
• Echogenic fluid contents, especially if varying echogenicity between locules, not consistent with a definitively benign lesion
• Associated ascites
• Combined gray-scale and Doppler ultrasound has equivalent diagnostic performance to MRI in primary adnexal mass evaluation, but MRI is useful for sonographically indeterminate or suspicious masses and in infirm, obese patients where US may be of limited value 12,13,20
• Advantages: highly sensitive, widely available, inexpensive and not associated with ionizing radiation
• Disadvantages: operator and body-habitus dependent and other areas of the abdomen are less well imaged

mrict

Magnetic Resonance Imaging (MRI)

• Preferred imaging modality for further evaluation of adnexal masses. MRI is the most useful second imaging test for (gray-scale) sonographically indeterminate masses compared to CT and Doppler US. 20,21 It is often used in pre-operative characterisation or post-surgical resection follow-up
• MRI is not significantly superior to CT in adnexal mass characterisation 12,13,22,23 but has superior contrast resolution, allowing better soft tissue visualisation, and is not associated with ionising radiation
• 1.5T MRI was 95.2% sensitive, 98.4% specific and 97.6% accurate in ovarian mass characterisation compared to histopathology as the reference standard in one prospective study. 22 Recent metaanalysis reported a pooled 91.9% sensitivity and 88.4% specificity in the diagnosis of adnexal masses. 12
• Features suggestive of malignancy on MRI 24
• Longest diameter >4cm
• Solid components with heterogeneous enhancement
• Cystic mass with vegetations and internal structures
• >3mm wall or septations thickness
• Lobulated masses
• Presence of necrosis
• Heterogeneously enhancing papillary projections
• Heterogeneously enhancing tumour vasculature
• Amorphic calcifications within the mass
• Ascites, peritoneal disease or lymphadenopathy
• An MRI examination should be done in 2 planes to make it an adequate examination. T1-weighted and T2-weighted acquisitions are essential to assess the pelvic anatomy and best characterise lesions. Contrast-enhancement using gadolinium-based agents is used to further classify a solid mass or to detect solid components in a cystic lesion 24,25

Computed Tomography (CT)

• CT is not significantly less accurate than MRI in primary adnexal mass evaluation 12,22,23 but has lower soft tissue resolution and is associated with ionising radiation, a disadvantage particularly in younger women
• 16 slice MDCT is 90.5% sensitive, 93.7% specific and 92.9% accurate in ovarian mass characterisation compared to histopathology as the reference standard in one prospective study. 22 Recent metaanalysis reported a pooled 87.2% sensitivity and 84% specificity in the diagnosis of adnexal masses 12
• It is useful 11,26
• Where extra-ovarian disease is suspected or needs to be excluded
• In ovarian mass characterisation when MRI is unavailable or contraindicated
• To characterise mature cystic teratoma by the presence of macroscopic fat and calcifications.
• In staging, pre-treatment planning and follow-up of ovarian cancer.

Positron Emission Tomography / CT

• Not recommended for the primary ovarian cancer detection and adnexal lesion characterisation because of high false positive and false negative results, but hyper-metabolic ovarian uptake in a postmenopausal women should be considered suspicious for malignancy 26,27
• Pooled 67% sensitivity and 79% specificity in the diagnosis of adnexal masses on recent metaanalysis 12
• Combined PET/CT is most useful in detecting suspected ovarian cancer recurrence 27,28

surgery

Surgery

• Where surgical management of a presumed benign ovarian cyst is indicated, a laparoscopic approach has a lower post-operative morbidity and shorter recovery time and is preferred to laparotomy in suitable patients 29
• Laparotomy is the preferred choice of approach when the likelihood of malignancy is high or when surgical staging and management is planned when malignancy has been confirmed
• Accuracy and adequacy of surgical staging by laparotomy and or laparoscopic approaches appear to be comparable and neither confers a survival advantage, but intraoperative tumour rupture which risks peritoneal tumour spread has been more frequently reported in patients undergoing laparoscopy 30
• The majority of benign adnexal masses can be managed expectantly and rarely require excision for clinical reasons 7

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