Warthin tumor-like papillary thyroid carcinoma with a minor dedifferentiated component: report of a case with clinicopathologic considerations

Abstract

Warthin tumor-like papillary thyroid carcinoma is an uncommon variant of papillary thyroid carcinoma. We report a rare case of Warthin tumor-like variant of papillary thyroid carcinoma with a dedifferentiated component consisting of a solid tumor area composed of neoplastic cells with a spindle to tall cell morphology associated with marked nuclear pleomorphism, atypical mitoses, and foci of necrosis. Although our patient presented with a locally aggressive disease (T3 N1b Mo), she is disease-free without radioiodine therapy after a 23-month follow-up period. We emphasize that Warthin tumor-like papillary thyroid carcinoma, like other morphological variants of papillary carcinoma, may occasionally undergo dedifferentiation. As this component may be only focally detectable, we suggest an extensive sampling of all large-sized (>3 cm) papillary thyroid carcinoma. Recognition of any dedifferentiated component in a Warthin tumor-like papillary thyroid carcinoma should be reported, including its percentage, because it may reflect a more aggressive clinical course.

Figure 1

FNAC showing a large neoplastic papilla (a) and numerous mono- or bi-nucleated polygonal to spindle-shaped cells with abundant eosinophilic cytoplasm and large nuclei with finely dispersed chromatin and one or two prominent nucleoli; some cells show marked nuclear pleomorphism (b).

Figure 2

Gross examination. The left thyroid lobe is completely replaced by two nodules which, on cut section, are yellowish in colour.

Figure 3

Histological examination of tumor showing the typical features of Warthin tumor-like PTC: papillae lined by oncocytic cells showing the typical nuclear features of PTC, and containing a dense inflammatory infiltrate, predominantly consisting of lymphocytes.

Figure 4

Dedifferentiation: tumor area composed of neoplastic cells with a spindle cell morphology and marked nuclear pleomorphism (a). Foci of tumor necrosis were scattered throughout the tumor (b).

Figure 5

Most neoplastic cells showing a diffuse immunostaining with cyclin-D1.