Aspiration cytology of an ectopic cervical thymoma misinterpreted as a lymphoproliferative lesion of the thyroid: A case report

Abstract

Abstract. Ectopic cervical thymoma is a rare tumor that originates from ectopic thymic tissue trapped during the migration of the embryonic thymus. To the best of our knowledge, only 14 cases of ectopic cervical thymoma, which include descriptions of the cytological features based on fine-needle aspiration (FNA), have been reported thus far. The current study describes the case of a 52-year-old male presenting with an enlarging anterior neck mass that been apparent for a number of years and was now accompanied by shortness of breath. FNA cytology revealed large numbers of small lymphocytes admixed with rare groups of large, polygonal cells that were interpreted to be reactive lymphocytes or possible follicular dendritic cells. However, no definite follicular or Hürthle cells were identified. Therefore, the overall cytological features were misinterpreted as a lymphoproliferative lesion. However, subsequent histological analysis of the resected left total lobectomy specimen determined a diagnosis of thymoma, type B1. Thus, awareness of this entity combined with a careful search for thymic epithelial cells may aid in determining a correct diagnosis when FNA is performed for the evaluation of a neck mass.

Thyroid Carcinoma Showing Thymic-Like Differentiation Causing Fracture of the Trachea

“…Nevertheless, final diagnosis is made by immunohistochemistry, which positively stains CASTLE cells for CD5, p63, and cytokeratin and negatively stains CASTLE cells for thyroglobulin, thyroid transcription factor-1 (TTF1), and calcitonin [ 6 , 9 , 15 ]. The expression of marker CD5 by CASTLE cells, along with Hassall's corpuscles, may be highly characteristic of the tumour [ 6 ].…”

Ectopic Cervical Thymoma: A Case Report and Review

“…However, it is important to be aware that cervical masses may be thymomas rather than thyroid masses. ECT is commonly located in the anterior area of the neck or subjacent to or inside the lower pole of the thyroid gland, and is commonly confused with a thyroid nodule [ 3 ]. Boman [ 1 ] reported the first patient with ECT in 1941.…”

“…Paraneoplastic manifestations are unusual in ECT. ECT usually has a benign clinical course, but an extremely low incidence of metastasis or recurrence has been reported [ 3 ].…”

“…FNAC is helpful when diagnosing ECT. To the best of our knowledge, only 14 cases of ECT that include descriptions of the cytological features based on FNAC have been documented to date [ 3 ]. ECT has a biphasic cellular pattern composed of both lymphocytic and epithelial cells.…”

Utilization of Flow Cytometry in Pediatric Fine-Needle Aspiration Biopsy Specimens

“…Another etiology of double-positive T cells can be ectopic thymic tissue, which is typically seen in young patients (as in our patient No. 9), and it may provide a benign explanation for a lymphoid neck mass in a young child even in the absence of detectable epithelial cells [29,30,31]. The key findings in these cases include a mixture of epithelioid cells, which are larger cells with round-to-oval nuclei and more abundant cytoplasm, with small lymphocytes and a relative absence or paucity of plasma cells, which are seen with lymphocytic thyroiditis, in addition to a relative paucity of tingible body macrophages and germinal center cells which are seen in reactive lymphoid hyperplasia [29.…”