Irving Dardick
Department of Laboratory Medicine and Pathobiology
University of Toronto, Toronto, Canada
History:
A 43-year-old man stated that a left neck mass had been present
for 3 months. This had been biopsied in a city in the vicinity
of Toronto and had been diagnosed as metastatic undifferentiated
carcinoma. As a result, he had been referred to the Toronto Hospital
for further clinical investigation. Biopsies of the left pyriform
fossa, base of tongue and nasopharynx were all negative, so the
surgeon rebiopsied the neck mass.
Light microscopy:
The lesion consisted of sheets of closely packed, relatively large
tumor cells (Fig. 1). Each tumor cell had a moderate amount of
amphophylic cytoplasm and the large nuclei had 1 to 3 prominent
nucleoli (Fig. 2). No glandular structures or intercellular bridges
were noted. Based on the diagnosis made on the first biopsy and
the epithelial characteristics of the current biopsy, immunohistochemistry
for a number of epithelial markers were done, but only epithelial-membrane
antigen (EMA) was positive (Fig. 3).
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| Figure 1. Sheets of compactly organized epithelioid tumor cells. | Figure 2. Tumor cells have moderate amounts of amphophilic cytoplasm and fairly uniform nuclei with clumped chromatin and usually a single fairly prominent nucleolus. |
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| Figure 3. Positive immunostain for epithelial membrane antigen (EMA). Many of the tumor cells are expressing this cell surface marker. |
Electron microscopy was done concurrently with the immunostaining on samples of glutaraldhyde-fixed tissue.
