Diagnosis of thymoma by fine-needle aspiration cytology: light and electron microscopic study of a case

Giant cervicomediastinal thymic cyst in an elderly: diagnosis by multimodality imaging and fine-needle aspiration cytology with immunocytochemistry

A 65-year-old woman, a non-smoker, presented to the pulmonary medicine outpatient department with chest pain, mild dyspnoea, right side neck swelling and mild facial puffiness. The cervical swelling was soft, non-tender and fluctuant on palpation. Multimodality imaging revealed a large, thin-walled cervicomediastinal cystic lesion with septations, haemorrhage, septal calcification and without any solid component. Image-guided fine-needle aspiration cytology from the septa with immunocytochemistry helped to establish the thymic origin and benign nature of the cyst preoperatively and differentiate it from cystic thymoma, lymphangioma, thymic carcinoma or lymphoma with confidence. As the haemorrhage resolved, the size of the swelling was significantly reduced, and the patient became asymptomatic due to which she deferred surgery but remained on close follow-up and was doing well. Thymic cysts can occur in a cervicomediastinal location, rare in elderly age, usually asymptomatic and clinically apparent when intracystic haemorrhage leads to an increase in size and chest pain.

Diagnostic pitfalls in fine-needle aspiration biopsy of the mediastinum

A retrospective review of 189 fine-needle aspiration (FNA) biopsies of the mediastinum from four university medical centers was performed. Review of Diff-Quick- and Papanicolaou-stained direct smears was performed from a series of 189 FNA biopsies along with surgical pathology correlation obtained in 42% of the cases. There were 28 (14.8%) nondiagnostic or unsatisfactory for diagnosis cases. Of the satisfactory FNA specimens with histologic correlation, 12 cases (6%) were discordant. These errors primarily involve subclassification of small-cell malignancies involving the mediastinum, including a misdiagnosis of small-cell carcinoma for lymphoma. Large-cell lesions that were problematic included the accurate diagnosis of Hodgkin's lymphoma including the separation from non-Hodgkin's lymphoma. Large-cell lymphoma with sclerosis was misinterpreted in two cases due to distortion of cells by the mesenchymal tissue and sparsely cellular smears. In two cases classification of primary germ-cell tumors and separation from metastatic carcinoma was a problem. In general, FNA of the mediastinum is an accurate procedure, but can be challenging in a minority of cases due to sparse cellularity of the lesions and accurate classification of a variety of neoplasms that occur in this region. These 12 discordant cases serve as the basis of our report.

Thymoma mimicking thyroid papillary carcinoma: another pitfall in fine-needle aspiration

Thymomas are composed of a mixture of epithelial and lymphoid cells. When the lymphoid cells predominate, the possibility of malignant lymphoma must be considered. Recently, a thymoma mimicking lymphoblastic lymphoma was reported in this journal as a diagnostic pitfall in a mediastinal aspiration. We encountered another diagnostic pitfall at the other end of the spectrum: a thymoma with a dominant epithelial component in which a papillary carcinoma of thyroid had to be considered in the differential diagnosis.

Cytologic patterns of metastatic thymoma: diagnosis by fine-needle aspiration biopsy

Thymomas are the most frequent primary tumors of the anterior mediastinum. These lesions are slow growing and can be locally invasive, but extrathoracic metastases are rare, occurring in less than 2% of cases. Fine-needle aspiration biopsy (FNAB) may be helpful in making the diagnosis of metastatic thymoma, with or without a clinical history of primary mediastinal thymoma. We report three cases of metastatic thymoma diagnosed by FNAB. Each case illustrates a distinctive cytologic pattern. While two of the patients had a history of histologically confirmed thymoma 11 and 13 years previously, a third patient presented with an enlarged supraclavicular lymph node and pulmonary nodules, and no prior diagnosis of thymoma. These cases demonstrate that based on distinctive cytologic patterns and features, a diagnosis of metastatic thymoma can be made with FNAB. Ancillary studies will often confirm the diagnosis.

Approach to the diagnosis and staging of mediastinal masses

Improvements in cytologic techniques have made needle biopsy much more helpful in diagnosing mediastinal masses. We have added thoracoscopy to the surgical armamentarium. Tumor markers facilitate accurate diagnosis. In the field of imaging, cysts can now be identified almost certainly and aspirated. Magnetic resonance imaging has changed the workup of patients with posterior mediastinal masses. Staging investigations should be based on the type of tumor and the likelihood of spread.