[ENTERIC ADENOCARCINOMA DIAGNOSED VIA IMMUNOHISTOCHEMISTRY AND GENOME TESTING OF A PORT SITE MASS AFTER...

Area of Science:

• Oncology
• Gastroenterology
• Pathology

Background:

• Advanced prostate cancer (cT3aN0M0, PSA 38.9 ng/mL, Gleason 8) initially responded to androgen blockade and surgery.
• Robot-assisted laparoscopic radical prostatectomy (RARP) revealed pT3bN1 disease with negative margins.

Purpose of the Study:

• To investigate an unusual case of prostate cancer recurrence presenting with features mimicking enteric adenocarcinoma.
• To highlight the importance of immunohistochemistry (IHC) and genomic testing in diagnosing rare metastatic patterns.

Main Methods:

• Patient treated with neoadjuvant androgen blockade, RARP, and subsequent surveillance.
• Diagnostic workup included serial PSA and CEA monitoring, imaging (PET/CT), gastro-colonoscopy, and biopsy of metastatic sites.
• Immunohistochemistry and genomic testing were performed on the recurrent mass.

Main Results:

• Post-RARP, PSA normalized but recurred with elevated CEA and hydronephrosis.
• Metastases identified in lungs, liver, peritoneum, and port site, initially without clear diagnosis.
• Biopsy and IHC of port site mass revealed enteric adenocarcinoma, distinct from prostate cancer.
• Genomic testing confirmed KRAS mutations consistent with enteric adenocarcinoma.

Conclusions:

• This case demonstrates a rare instance of prostate cancer recurrence with features of enteric adenocarcinoma.
• Accurate diagnosis of unusual metastatic patterns requires advanced techniques like IHC and genomic testing.
• Early identification and appropriate chemotherapy are critical for managing such complex oncological presentations.