S. A. Morrison1, P. Sadow1, C. Lubitz1, R. Hodin1, A. Stephen1 1Massachusetts General Hospital,Surgery,Boston, MA, USA
Introduction: Diffuse sclerosing variant of papillary thyroid carcinoma (DSV-PTC) is a rare variant of papillary thyroid carcinoma (PTC), accounting for 0.7%-5.3% of PTC cases. This variant historically exhibits more aggressive behavior than classical PTC. However, prior studies have been few in number and have not investigated the role and potential consequences of recurrent laryngeal nerve (RLN) involvement. In this series, we present the incidence and implications of nerve involvement in this PTC variant.
Methods: Thirty-four patients were retrospectively reviewed over a 13 year period at a single institution. Records from patients undergoing thyroidectomy were queried from a pathologic database. Patients were selected for inclusion if three or greater criteria were met for diffuse sclerosing variant, as defined by the WHO. Clinical and histopathological characteristics of study patients were reviewed and compared to values reported in the literature for patients with classical PTC. Operative reports and laryngoscopies were reviewed for evidence of nerve involvement and post-operative paralysis.
Results: Compared to classical PTC, our study patients were more likely to be younger (average age 40 vs. 46), have larger tumors (3.9cm vs. 2.2cm), with higher rates of cervical lymph node involvement (90.6% vs. 43.0%). Our case series revealed a significantly greater incidence of multifocality (87.5% vs. 17.2%) and extra-thyroidal extension (75.8% vs 59.6%). Additionally, DSPC study patients were more likely to have persistent or recurrent disease (26.9% vs 17.2%) as well as distant metastasis (11.5% vs. 4.3%). Our cohort demonstrated a 30% incidence of RLN involvement as reported by the operating surgeon, resulting in vocal cord palsy in 7/34 patients (20.6%). Three of these seven patients underwent intentional nerve sacrifice. The remaining 4 patients had transient vocal cord palsies that resolved.
Conclusions: In this series, DSV-PTC was associated with greater infiltration and aggressive behavior compared to patients with classical PTC. In particular, RLN involvement was noted in 30% of patients, and the incidence of post-operative RLN palsy was 20.6%. These findings have important implications with regard to the pre-operative work-up, intra-operative decision making, and post-operative management of patients with DSV-PTC.