Thymic Carcinoma Associated With Multilocular Thymic Cyst

Abstract

We present 7 cases of thymic carcinoma associated with a multilocular thymic cyst (MTC). The patients were 5 men and 2 women aged 22 to 71 years (mean, 49.3 y). Clinically, 6 patients presented with chest, sternal, or upper extremity pain, and in 1 patient the tumor was an incidental finding. Grossly, 4 tumors were described as multilobulated solid-cystic masses, whereas 3 cases were described as solid tumors with a white-yellow cut surface and areas of hemorrhage and necrosis. The tumor size ranged from 7.0 to 10.0 cm (mean, 8.1 cm). Histologically, 4 cases were classified as squamous cell carcinoma, and 1 each as sarcomatoid (spindle) cell carcinoma, papillary carcinoma, and basaloid carcinoma. In addition to the tumor component, prominent MTC changes were observed in the adjacent remnant thymic tissue. Immunohistochemical studies were conducted in 2 cases of squamous cell carcinoma. The neoplastic cells were positive for cytokeratin (CK), CK5/6, and p63, and showed variable reactivity for CK7 and CD5. Clinical follow-up showed that 4 patients were alive and well, 2 to 63 months after diagnosis, and 3 patients were alive with disease, 13 to 33 months after diagnosis. This study expands the morphologic spectrum of thymic carcinoma associated with MTC, detects a higher incidence than previously believed, and highlights the importance of adequate sampling and proper evaluation of all cystic lesions of the anterior mediastinum so as not to mistake malignancy for a benign cystic process.

Thymoma and thymic carcinoma associated with multilocular thymic cyst: a clinicopathologic analysis of 18 cases

“…MTCs are mostly considered to be acquired lesions from inflammatory conditions, and in some cases are associated with thymomas or TCs [6, 9, 15]. The prevalence of MTCs with thymoma or TC are approximately 10.9 and 18.2%, respectively, as reported by Weissferdt and Nakamura [6, 9]. Notably, our 18 cases were obtained from 309 consecutive cases of thymoma and TC, accounting for approximately 5.8%.…”

“…This relatively lower proportion raises the possibility that thymoma or TC associated with MTC may be more uncommon in the Chinese population. MTCs associated with thymomas or TCs have sporadically been reported in association with type A, type B, micronodular thymoma, SCC, basaloid carcinoma, papillary carcinoma and mucoepidermoid carcinoma [3, 4, 6, 8, 9, 15, 16]. In this study, we add atypical type A thymoma and LELC to MTCs associated with thymomas or TCs which have never been described in the previous reports.…”

“…Unilocular cysts are considered to arise from the embryologic remnants, contain clear fluid, have thin walls, and show no evidence of inflammation on histopathologic examination [14, 15]. MTCs are mostly considered to be acquired lesions from inflammatory conditions, and in some cases are associated with thymomas or TCs [6, 9, 15]. The prevalence of MTCs with thymoma or TC are approximately 10.9 and 18.2%, respectively, as reported by Weissferdt and Nakamura [6, 9].…”

NUT midline carcinomas in the thymic region

“…Primary mixed thymic tumor also has to be The association of these tumors with carcinoma with t(15;19) translocation needs closer examination. 17,18 Translocation carcinomas can have very similar histology. Recently, these tumors have been shown to have NUTM1 gene fusion; this can be analyzed by cytogenetic studies or specific probes that detect the fusion.…”

“…Basaloid variant of thymic carcinoma tends to have extensive glandular or cyst-like spaces and exhibit peripheral palisading. 6,16,17 Poorly differentiated squamous cell carcinomas consist of sheets or nests of large polygonal cells with prominent nucleoli and a moderate amphophilic amount of cytoplasm. Small cell neuroendocrine carcinoma is an important consideration, particularly if the squamous component is small and not appreciated.…”