Clinical analysis of 82 cases of carcinoma showing thymus-like differentiation of the thyroid

Abstract

The aim of the present study was to summarize the clinical characteristics, diagnosis, treatment and prognosis of carcinoma showing thymus-like differentiation of the thyroid (CASTLE). A search of the relevant literature was conducted, which identified 82 cases of CASTLE reported to date. A review of the clinical and auxiliary examination data, treatment, pathological findings and follow-up of these cases was performed. The clinical manifestations of CASTLE varied and did not demonstrate specificity. During ultrasound examination, CASTLE was described as a solid and hypoechoic mass, and the echo was typically observed to be heterogeneous. In computed tomography (CT), CASTLE was demonstrated to be a well-defined, soft tissue density mass without calcification, which appeared enhanced following administration of contrast medium. In emission CT, CASTLE was revealed as a ‘cold nodule’. A total of 78 patients underwent radical surgery, and 12 patients experienced recurrence. Lymph node metastasis did not promote recurrence, and postoperative radiation was not able to reduce the recurrence rate (P=0.144 and 1.000, respectively). The median follow-up time was 14 months (range, 1–312 months). Typical immunohistochemical examinations demonstrated the specimens to be positive for cluster of differentiation (CD)5, CD117, cytokeratin 19, epithelial membrane antigen and tumor protein 63, and negative for calcitonin, thyroglobulin and thyroid transcription factor-1. Thyroid CASTLE is a rare malignancy whose exact diagnosis relies on pathological examination, particularly immunohistochemistry, since preoperative examinations are usually unable to provide an exact diagnosis. Radical resection is the primary treatment for CASTLE, which presents favorable prognosis.

Carcinoma showing thymus like elements: Report of a case with EGFR T790M mutation

“…Although CASTLE is a slow growing tumor with indolent behavior, local recurrences and regional lymph node metastasis can occur. Of the 82 cases reported till 2015, nodal `metastasis was observed in 22 patients, lung metastasis in 2 patients and recurrence in 12 cases . According to the same review, postoperative radiotherapy did not reduce the recurrence rate.…”

“…The diagnostic utility of FNAC for CASTLE is limited in view of overlapping features with various other tumors. Among all the cases reported in the literature, cytological diagnosis of CASTLE was accomplished only in two cases . Most of the other cases were diagnosed as poorly differentiated malignant tumor.…”

“…CASTLE most commonly presents in middle aged adults with a slight female preponderance. In one of the recent and largest series by Ge et al mean age of presentation was 48.8 ± 12.8 years with painless neck swelling being the most common symptom. Marked racial predilection was evident in their study, where majority of cases were from China (72%) followed by Japan (13.4%).…”

“…Of the 82 cases reported till 2015, nodal metastasis was observed in 22 patients, lung metastasis in 2 patients and recurrence in 12 cases. 9 According to the same review, postoperative radiotherapy did not reduce the recurrence rate.…”

Two cases of thyroid gland invasion by upper mediastinal carcinoma

“…We had to distinguish between a thymic carcinoma and a carcinoma showing thymus-like differentiation (CASTLE). These markers cannot help differentiate between thymic carcinomas and CASTLE (6). Considering the image findings, we diagnosed the tumor as a thyroid invasion of thymic carcinoma because the main lesion was within the mediastinum.…”