Irving Dardick
Department of Laboratory Medicine and Pathobiology
University of Toronto, Toronto, Canada
History:
A 55-year-old woman was discovered to have an anterior mediastinal
mass and had a fine-needle aspiration biopsy as the initial phase
of her investigation.
Light microscopy:
The smear (Fig. 1) and cell block (Fig. 2) preparations were largely
composed of small, normal-appearing lymphocytes with the occasional
larger cell scattered among the lymphocytes. The nuclei of what
seemed to be epithelial cells generally had dispersed heterochromatin
and rather inconspicuous nucleoli. Antibodies to cytokeratins
were all negative raising doubts about the diagnosis of thymoma.
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| Figure 1. Smear preparation of FNAB with many lymphocytes and the occasional larger epithelioid appearing tumor cells, some of which are also evident in the clump of tumor cells on the right. | Figure 2. Cell block preparation of FNAB. Many normal appearing lymphocytes with larger cells scattered in between. |
As a concurrent part of the diagnostic investigation, electron microscopy was done on samples of glutaraldhyde-fixed tissue obtained from the needle rinse following preparation of the smears and cell block.
