Diagnosis and Discussion:
The ultrastructural features, particularly the microfilamentous
core rootlets and glycocalyceal bodies, are consistent with a
metastatic adenocarcinoma of the gastrointestinal tract.
The confirmation of signet-ring type tumors cells by electron
microscopy and the history of a partial gastrectomy for a gastric
"ulcer" indicate that the original diagnosis was a gastric
carcinoma. Subsequent clinical investigation showed no evidence
of local recurrence, but extensive involvement of para-aortic
and right inguinal lymph nodes with metastatic tumor. Skin involvement
was an extension of the adenocarcinoma from the inguinal lymphadenopathy.
The woman died of her metastatic disease three months later.
Of patients clinically assessed for tumor, in about 10 to 15 percent no primary lesion will detected, ie, a neoplasm of unknown primary origin (1). So, for clinicians, this is a problem that arises with some frequency. A number of studies have shown that electron microscopy can provide additional diagnostically useful information that may establish an exact diagnosis or at least significantly narrow the differential diagnosis (2,3). The case presented illustrates the effectiveness of ultrastructural features in solving what amounts to determining the original primary site for metastatic tumor.
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