An Unusual Case of Acute Appendicitis due to Metastatic Prostatic Adenocarcinoma

Figure 1

(a) A representative histologic section of the appendix. At scanning magnification, a gland-forming neoplasm composed of tightly-packed acini involves the appendix from the mucosa to the muscularis propria, H&E ×20. (b) At higher magnification, the tumor demonstrates variably sized, but predominantly small, back-to-back acini composed of cells with clear to amphophilic cytoplasm and enlarged nuclei. Amphophilic secretion is present in some tumor lumina, H&E ×100. (c) The tumor cells show strong and diffuse nuclear positivity for NKX3.1, confirming the diagnosis of metastatic prostatic adenocarcinoma, ×100. (d) The tumor cells also show strong cytoplasmic immunopositivity for prostate-specific antigen, further confirming the diagnosis. The luminal epithelium of the appendix (bottom left of the image) is unstained, providing a negative control for the test, ×100.

(a)

(b)

(c)

(d)