Differential diagnosis of non-diffuse primary thyroid lymphoma and papillary thyroid carcinoma by ultrasound combined with computed tomography

Abstract

Background: Primary thyroid lymphoma (PTL) and papillary thyroid carcinoma (PTC) are both thyroid malignancies, but their therapeutic methods and prognosis are different. This study aims to explore their sonographic and computed tomography(CT)features, and to improve the early diagnosis rate.

Methods: The clinical and imaging data of 50 patients with non-diffuse PTL and 100 patients with PTC confirmed by pathology were retrospectively analysed.

Results: Of the 150 patients, from the perspective of clinical data, between non-diffuse PTL and PTC patients existed significant difference in age, maximum diameter of nodule, asymmetric enlargement and Hashimoto's thyroiditis (P < 0.001), but not in gender ratio, echo texture, cystic change and anteroposterior-to-transverse ratio (P > 0.05). With respect to sonographic feature, non-diffuse PTL patients had a higher proportion than PTC patients in markedly hypoechoic, internal linear echogenic strands, posterior echo enhancement, rich vascularity, lack of calcification and homogeneous enhancement, with statistically significant difference (P < 0.05), while PTC patients had a higher proportion than non-diffuse PTL patients in irregular border, circumscribed margin, capsular invasion and significant enhancement, with statistically significant difference (P < 0.001). With respect to CT feature, non-diffuse PTL patients were significantly different from PTC patients in the non-contrast CT value mean, venous phase CT value mean, enhanced intensity and homogeneity of nodules (P < 0.05). Multivariate logistic regression analysis showed that age (OR = 1.226, 95%CI:1.056 ~ 1.423, P = 0.007), posterior echo enhancement (OR = 51.152, 95%CI: 2.934 ~ 891.738, P = 0.007), lack of calcification (OR = 0.013, 95%CI: 0.000 ~ 0.400, P = 0.013) and homogeneous enhancement (OR = 0.020, 95%CI: 0.001 ~ 0.507, P = 0.018) were independent risk factors.

Conclusions: Sonographic and CT features of the presence of posterior echo enhancement, lack of calcification and homogeneous enhancement were valuable to distinguishing non-diffuse PTL from PTC.

Keywords: CT; Papillary thyroid carcinoma; Primary thyroid lymphoma; Sonography.

Fig. 1

Flow chart of study participants

Fig. 2

A 70-year-old female patient with neck tumor for more than 4 months (A) Transverse image of ultrasonography, showing a heterogeneous hypoechoic nodule with circumscribed margin on the right lobe of thyroid. The arrows show the internal linear echogenic strands; (B) Longitudinal image of ultrasonography. The arrow shows a significant posterior echo enhancement; (C) Blood flow spectrum, showing rich blood flow signals; (D) Non-contrast CT. The arrow shows the CT of the right lobe of thyroid; (E) Venous phase CT, showing homogeneous mild enhancement in the right lobe nodule and the density of it is lower than that of the thyroid parenchyma; (F) Pathological results, showing mucosa- associated lymphoid tissue lymphoma (MALT) (*400)

Fig. 3

A 50-year-old female patient with neck tumor for 3 months (A) Transverse image of ultrasonography, showing heterogeneous hypoechoic nodules on the left lobe of thyroid with irregular border; (B) Longitudinal image of ultrasonography. The arrows show the internal small calcification; (C) Blood flow spectrum, showing rich blood flow signals; (D) Non-contrast CT, showing low-density nodules on the left lobe of thyroid; (E) Venous phase CT, showing heterogeneous significant enhancement of nodules in the left lobe of thyroid; (F) Pathological results, showing papillary thyroid carcinoma (* 400)