Fine-needle aspiration cytology of thymic basaloid carcinoma: case studies and review of the literature.

We report the features in fine-needle aspiration biopsy (FNAB) of thymic basaloid carcinomas. This is a rare neoplasm, of which there are only three documented in our hospital files. To the best of our knowledge, this is the first fine-needle aspiration (FNA) report on basaloid carcinoma of the thymus. This is a tumor in which the FNA diagnosis is difficult and the differential diagnosis is broad. We describe the cytologic features encountered in the three cases, and immunohistochemical and ultrastructural findings so as to raise awareness of this entity in the differential diagnosis of thymic neoplasms on FNABs. The cases studied included three male patients, aged 73, 65, and 50, who presented with anterior mediastinal masses, with no primary tumor elsewhere. FNAB was performed on two cases, followed by thymectomy. One case, additionally, had metastasis to a cervical lymph node, and the other two were associated with thymic cysts. The diagnoses on all three cases were thymic basaloid carcinoma.