Fine needle aspiration cytology of thymoma.

Thymoma is the 2nd most common mediastinal tumor found in Thai people. Cytologically it has a characteristic biphasic cell pattern and can be differentiated from other mediastinal lesions. We reviewed 14 aspirated samples, initially diagnosed as thymoma among a total of 80 mediastinal aspirations, obtained during a period of 6 years. Revised cytologic diagnosis was made and compared with histopathology from needle biopsy, surgical biopsy and surgical removal in each case. All cytologic samples revealed a mixture of epithelial cells and lymphocytes in varying proportions. Histopathologic samples were available in 13 patients and showed 12 thymomas and 1 immature teratoma. While all thymomas revealed characteristic cytologic features, a case of mediastinal immature teratoma with unsatisfactory aspirated sample revealed resembling features and it was very difficult to differentiate such a tumor from thymoma.

Mucinous cystadenocarcinoma of the lung.

One case of primary mucinous cystadenocarcinoma of the lung is recorded. The patient was a 67-year-old male with a peripheral mass of the right lung, treated by pneumonectomy. The tumor was made up of fibrous-walled cyst containing abundant mucinous material. Microscopically, it revealed the same morphology as its counterparts arising in other common sites: ovary, appendix and pancreas. The transitional change of the cystic lining from benign features resembling reactive respiratory epithelium to frank malignancy indicated that the tumor had the origin from the lung. This is a very rare intrapulmonary neoplasm that should be differentiated from metastatic lesion and mucinous bronchioloalvolar carcinoma due to different clinical courses and prognoses.

Solitary fibrous tumor arising from hyperplastic thymus.

One case of a solitary fibrous tumor arising from the hyperplastic thymus is recorded. The patient was a 37-year-old female who presented with an anterior mediastinal mass. Thoracotomy was performed and revealed that the tumor arose on a pedicle from the posteroinferior surface of the enlarged thymus. The pathologic findings were characteristic of a solitary fibrous tumor. This is a very rare neoplasm that occurred in the mediastinum and had evidence of thymus gland in origin.

Imprint cytologic examination as an adjunct to frozen section.

Imprint cytologic examination should be performed in all cases of frozen sections, especially when tumor or infectious agents are suspected. It has been shown to be a useful adjunct to the use of frozen sections. It gives superior results in cases of small biopsied specimens, lymph nodes, infective cases, isolated tumor cells or hemorrhagic tissue. From our series of 80 cases, the total diagnostic accuracy was 29/32 cases (90.6%) for benign tumors, 45/48 cases (93.7%) for malignant tumors, with 2/80 cases (2.5%) of false positive rate in borderline ovarian tumors, and 4/80 cases (5%) of false negative rate, in which 3 cases were due to insufficient material.

Fine needle aspiration biopsy of lung lesions.

Fine needle aspiration of the lung is an excellent method in the diagnosis of lung cancers, mediastinal tumors and other specific inflammatory lung lesions. The correct diagnosis of lung cancer by FNA in this study was a reported sensitivity of 97.8 per cent and specificity of 100 per cent. There was no false positive in this study, and only 1/60 patient had pneumothorax, which was cured after insertion of chest drain.