Case 137

A 56 year old male with a remote history of thyroid lesion s/p thyroidectomy and now he presented with large neck lymph node. The outside diagnosis is unknown.

1. What's the best interpretation?

A: Follicular carcinoma

B: Papillary thyroid carcinoma

C: Follicular lesion, see comment

D: Benign residual thyroid follicles

Answer

- Thyroid follicular lesion (see Comment). 

- No lymphoid tissue identified.

COMMENT: The patient’s history of right thyroid lobectomy is noted. Immunohistochemical staining demonstrates positivity for TTF-1 and PAX8, consistent with thyroidal origin. No invasive growth, papillary-like nuclear features, mitotic activity, or necrosis is identified. The differential diagnosis on this limited biopsy includes benign thyroid follicular nodular disease and follicular thyroid carcinoma. Clinical and radiographic correlation is recommended.

Case credit: UCSD Pathology

Author: Wangpan Jackson Shi, MD