Carcinoma Showing Thymus-like Differentiation (CASTLE) with Synchronous Papillary Thyroid Carcinoma: A Case Report and Review

Abstract

Carcinoma showing thymus-like differentiation (CASTLE) is a rare malignant tumor that accounts for 0.1%–0.15% of all thyroid cancers. More than half of the patients have tumor extension to adjacent organs, including the recurrent laryngeal nerve, trachea, and esophagus. The diagnosis of CASTLE is based on histology and immunohistochemistry. A 58-year-old female patient complained of hoarseness for one and half years. Right side vocal cord palsy was diagnosed by fiberscopy. Thyroid sonography revealed right thyroid tumors, which were reported to be papillary thyroid carcinoma through FNAC. Total thyroidectomy with central lymph node dissection was performed. Pathologist found 2 isolated malignancy tumors. One patient in the right thyroid lobe had papillary thyroid carcinoma features. The other extrathyroid tumor seemed to be separated from the first tumor and invaded the thyroid capsule. After multiple immunohistochemical studies, PTC synchronous CASTLE was the final diagnosis. Coexisting PTC and CASTLE is very rare. This is the first report to describe a case showing PTC at first, while subsequent pathologic examination revealed the presence of CASTLE in addition to PTC. Since the prognosis of CASTLE is favorable, the treatment is different from other aggressive thyroid cancers, such as poorly differentiated or anaplastic thyroid carcinoma.

Coexistence of intrathyroid thymic carcinoma and papillary thyroid carcinoma: a case report and literature review

“…However, we recommend considering a total thyroidectomy combined with complete neck dissection in the management of ITTC, to minimize the risk of potential recurrence. Secondly, in addition to our case, the coexistence of ITTC and PTC has been documented in seven previously reported cases (12)(13)(14)(15)(16)(17). Nonetheless, the increasing number of reported cases with this simultaneous occurrence may provide novel insights into the underlying pathophysiological mechanisms of ITTC.…”

“…To the best of our knowledge, this is the eighth case of the concurrent occurrence of ITTC and PTC within the same thyroid gland (12)(13)(14)(15)(16)(17). While a direct pathological association between ITTC and PTC has not been reported in the literature, some potential correlations, such as shared genetic alterations and environmental factors, may be involved in this coexistence.…”

“…The coexistence of ITTC and papillary thyroid carcinoma (PTC) in the same thyroid gland is an extremely rare condition that has been reported only in a limited number of cases (12)(13)(14)(15)(16)(17). As this coexistence may potentially affect the treatment strategies, prognosis, and outcomes of the ITTC, clinicians should be aware of this condition.…”