Solid papillary thyroid carcinoma with focal classic type component, 2.5 cm, diffusely involving the left thyroid lobe. See note. There is extensive lymphatic invasion with multiple satellite tumor nodules throughout the right lobe and left lobe. No necrosis is identified. No increased mitotic activity.
Immunohistochemistry stains performed at the outside institution and are reviewed at the MGH shows that of the tumor cells are positive for TTF-1 as well is the background thyroid is positive for TTF-1 and thyroglobulin. P63 is focally positive within the intralymphatic tumor cells, highlighting the squamous metaplasia. p40, estrogen receptor, synaptophysin, and calcitonin are negative. Immunostain for beta-catenin is negative (membranous stain only).
Immunohistochemistry performed at MGH for HBME-1 shows strong membranous immunoexpression of the cells within the numerous foci of papillary thyroid carcinoma. HBME-1 also highlights numerous foci of lymphatic invasion. P53 shows a wild-type pattern.
Immunohistochemistry for pan-TRK is focally positive in tumor cells with a background staining, suggestive of an NTRK fusion. Subsequent molecular evaluation is recommended. Immunohistochemistry performed to assess for BRAF p.V600E using a variant specific BRAF antibody is negative, consistent with an absence of BRAF p.V600E in this tumor. Immunohistochemistry for ALK TR shows a lack of cytoplasmic ALK expression. The finding is unlikely to be associated with an ALK fusion gene product.
Immunohistochemistry for RAS p.Q61R is negative in tumor cells and is consistent with absence of RAS family mutations of Q61R type.
