Nuclear features of papillary carcinoma such as intranuclear inclusions are not hard to find in this variant.
Papillae are lined by cells with oncocytic cytoplasm and round to oval nuclei. The papillary stalks are expanded by a rich inflammatory infiltrate, predominantly composed of plasma cells with admixed lymphocytes.
Chronic lymphocytic thyroiditis (Hashimoto's) is seen adjacent to the tumor in the upper to mid left portion of the image. This finding is nearly always present in this variant of PTC.
A different case shows similar features, with crowded stout papillae filled with a lymphoplasmacytic infiltrate. This case also had adjacent exuberant chronic lymphocytic thyroiditis.
Most of the tumor showed this pattern of back-to-back papillae, but some case have admixed other variants as well.
Focal cystic change with pale eosinophilic colloid minics even the fluid in Warthin's tumors of salivary gland; some cases have shown prominent cystic changes.
In 1995, Apel et al reported 13 cases of this unusual histological variant of papillary carcinoma and named it Warthin-like papillary carcinoma, owing to its close histologic resemblance to a tumor encountered in salivary glands (Apel). These tumors most often arise in a background of chronic lymphocytic thyroiditis, and as such have been the source of cytological interest due to their ability to hide in this background. Nuclear features of papillary carcinoma, however, are not difficult to find and help in their cytological identification.
Often presents with a palpable mass.
Follow-up on these patients demonstrates that these tumor behave similarly to conventional papillary carcinoma. Interestingly, one case report documented anaplastic change, with demise due to widespread metastases.
Baloch ZW, LiVolsi VA. Warthin-like papillary carcinoma of the thyroid. Arch Pathol Lab Med. 2000 Aug;124(8):1192-5.
Apel, R. L. , S. L. Asa , and V. A. LiVolsi . Papillary Hürthle cell carcinoma with lymphocytic stroma: “Warthin's-like tumor” of the thyroid. Am J Surg Pathol 1995. 19:810
Lam KY, Lo CY, Wei WI. Warthin tumor-like variant of papillary thyroid carcinoma: a case with dedifferentiation (anaplastic changes) and aggressive biological behavior. Endocr Pathol. 2005 Spring;16(1):83-9.