Table 2.

Histologic findings and observed fusions in NTRK-rearranged thyroid carcinomas.

Case #	Original diagnosis	Revised diagnosis	Multinodularity	Fusion	Growth Pattern(s)	LVI	PNI	ETE	Margin
1	PTC	PTC	na	EML4-NTRK3	Primary tumor not availablea; brain metastasis was oncocytic forming microfollicles and papillae	+	−	−	−
2	PTC	PTC	+	ETV6-NTRK3	Predominantly (90%) follicular with scatted papillae (10%); psammoma calcifications	+	−	+st	+
3	PTC	PTC	+	ETV6-NTRK3	Predominantly (90%) follicular with scatted papillae (10%); psammoma calcifications	+	−	+st	−
4	PTC	PTC	+	ETV6-NTRK3	Predominantly (70%) follicular with scatted papillae (20%); 10% tall cell; no psammoma calcification	+	−	+sm	+
5	PTC	PTC	+	RBPMS-NTRK3	Primary tumor not availablea; lymph node metastasis was predominantly (90%) follicular with scatted papillae (10%)	+	−	+sm	+
6	PTC	PTC	+	RBPMS-NTRK3	Predominantly (90%) follicular with scatted papillae (10%); psammoma calcifications	+	−	+st	−
7	PTC	PTC	+	SQSTM1-NTRK1	Labyrinthine pattern formed by coalescent true and abortive papillae; no psammoma calcification	+	−	−	+
8	PTC	PTC	+	SQSTM1-NTRK3	Insular and oncocytic with scattered microfollicles; increased mitotic activity; no psammoma calcification	+	−	+sm	+
9	PTC	PTC	+	TPR-NTRK1	Packeted papillae with psammoma calcifications	+	−	+st	−
10	PTC	PTC	+	TPR-NTRK1	Packeted papillae with psammoma calcifications	+	+	+st	+
11	PTC	SC	+	ETV6-NTRK3	Microcystic; intracellular and extracellular eosinophilic material; no psammoma calcifications	+	−	+sm	+

PTC papillary thyroid carcinoma, SC secretory carcinoma, na not available, LVI lymphovascular invasion, PNI perineural invasion, ETE extrathyroidal extension, microscopic or macroscopic, +st present in perithyroidal soft tissue, +sm present in strap muscle.

^aFor cases #1 and #5, the histologic slides for the primary tumor were not available for the study, and written reports were reviewed.