Differentiating Follicular Thyroid Carcinoma from Benign Thyroid Nodules, A Study of Thyroid Glands with Both Pathologies

    • Presentation Speakers / Moderators

    One challenge with observing thyroid nodules is how not to miss a follicular carcinoma (FTC). We evaluated the sonographically differentiating features between FTCs and benign nodules in thyroid glands containing both pathologies.

    Retrospective review of clinical, radiological and pathological charts.

    Between 2009 to 2016, twenty-three patients had both pathologies (mean age = 46.7 years), yielding 24 FTCs and 61 co-existing benign nodules. Three patients underwent serial ultrasound.
    Internal vascularity is more common in all subtypes of FTCs: 45.45% of minimally invasive FTC (MIFTC) vs. 5.56% of benign nodules (p=0.010), 80% of widely invasive FTC (WIFTC) vs. 0% of benign nodules (p<0.001) and 50% of FTC of non-specified invasiveness vs. 0% benign nodules (p<0.001). The mean dimension of MIFTCs is 35.09mm vs. 14.68mm in its coexisting benign nodules (p=0.018). That of WIFTCs is 41.8mm vs. 5.51mm in its coexisting benign nodules (p=0.043). 

    A hypoechoic rim is associated with FTC of non-specified invasiveness (p=0.010) and potentially WIFTC (p=0.052) but not MIFTC (p=0.917). Ill-defined margins are potentially associated with WIFTC (p=0.052) and FTC of non-specified invasiveness (p=0.073) but not MIFTC (p=0.153). However, these two features are absent in three-quarters of FTCs. Growth rate of FTCs (mean=0.18mm/month) and benign nodules (mean=0.02mm/month) does not differ significantly (p=0.738). In fact, one MIFTC regressed by 0.41 mm/month. 

    Internal vascularity is the only consistently differentiating feature between FTCs and benign nodules. Growth rate is unreliable. Using internal vascularity and size to choose the nodules for needle biopsy may reduce the risk of missing FTCs when a conservative approach to thyroid nodule evaluation is adopted. ”


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