Columnar Cell Variant of Papillary Thyroid Carcinoma: Ultrasonographic and Clinical Differentiation between the Indolent and Aggressive Types

Abstract

Objective: To evaluate the ultrasonography (US) features and clinical characteristics of columnar cell variant of papillary thyroid carcinoma (CCV-PTC) that can predict disease progression.

Materials and methods: Six cases of CCV-PTC were identified via surgical pathology analysis at our institution from 1994 to 2016. The histological, architectural, and cytological features met the diagnostic criteria of CCV-PTC. We reviewed the US features and clinicopathological findings in the six cases.

Results: An indolent clinical course was observed in four young female patients aged 27-34 years (median: 32 years), while two older patients aged 55 years or 70 years had an aggressive clinical course. All patients underwent total thyroidectomy and radioiodine therapy. The indolent group included patients with T1 and nodal metastasis, where the disease was not observed during the follow-up period (range: 8-17 years). On the other hand, a larger tumor size (1.8 cm and 6.0 cm), gross extrathyroidal extension to the muscle and lymph node, and distant metastasis were observed in the aggressive group. In one male patient, recurrence occurred immediately after operation, and this patient died 4 years after the diagnosis of thyroid cancer. Based on US, the individuals from the indolent group had a smooth margin, except for one. Both cases in the aggressive group had a microlobulated margin.

Conclusion: Favorable prognosis in CCV-PTC is observed in young patients with T1 staging and demonstrates a smooth margin at US. These US findings might help exclude the same treatment as the aggressive type in the indolent type of CCV-PTC.

Keywords: Histology; Papillary thyroid carcinoma; Prognosis; Ultrasonography.

Fig. 1. Case 3: 27-year-old woman with CCV-PTC diagnosed with fine-needle aspiration cytology.

Transverse (A) and longitudinal (B) US shows 1.8-cm hypoechoic solid nodule (arrows) with oval shape, smooth margin, and microcalcification confined to right thyroid gland. (C) Note microfollicles or elongated follicles of columnar cells (arrows) with palisading oval nuclei and eosinophilic cytoplasm, and minimal papillary nuclear features, Hematoxylin & eosin (× 400). CCV-PTC = columnar cell variant of papillary thyroid carcinoma, US = ultrasonography

Fig. 2. Case 5: CCV-PTC in 55-year-old man.

Transverse (A) and longitudinal (B) US shows 2.4-cm hypoechoic solid nodule (arrows) with irregular shape, microlobulated margin (arrowheads), and microcalcification (thin arrows) in right thyroid gland. Nodule presented infiltrative anterior margin abutting to anterior strap muscle which was suspicious for extrathyroidal extension. Finally, gross extrathyroidal extension on pathology and surgical report was present. He was included in aggressive group and died from disease 4 years after diagnosis.