P1220 - A Prostatic Seeding Leading to an Uncommon Cause of Constipation

Matthew Everwine, DO¹, Summar Salim, DO², Wei Hong, MD³, Richard Walters, DO^4
1Rowan SOM/Jefferson Health NJ, Franklinville, NJ; ²Rowan University School of Osteopathic Medicine, Cherry Hill, NJ; ³Thomas Jefferson University, Cherry Hill, NJ; ⁴Jefferson Health, Cherry Hill, NJ

Introduction: Small cell carcinomas (SCCs) are aggressive tumors that commonly arise from the neuroendocrine system. Given their predominance within the lungs, those outside of the lungs are categorized as extrapulmonary SCCs. The prostate and the gastrointestinal system are some sites implicated in extrapulmonary SCCs. Colorectal SCCs are rare with an approximate frequency less than 1%. Herein reports a case of SCC of the prostate with metastatic rectal involvement presenting as constipation.

Case Description/Methods: A 58 year old male presented for constipation over one week with associated weight loss and rectal pain. A CT scan of the abdomen and pelvis demonstrated a mass within the posterior bladder measuring 5.4x6cm inseparable from the prostate, bilateral hydronephrosis, diffuse rectal wall thickening, and retroperitoneal lymphadenopathy. The patient was taken for a cystoscopy and trans-perineal prostate biopsy. Biopsies obtained revealed high grade neuroendocrine small cell carcinoma. Immunohistochemical stains were positive for AE1 and synaptophysin with focal positivity for chromogranin. History revealed the patient underwent transrectal ultrasound of the prostate four months prior which was negative. A flexible sigmoidoscopy was performed which showed a friable ulceration within the rectum. Biopsy redemonstrated high grade neuroendocrine small cell carcinoma suggesting metastasis from the prostate primary. Immunohistochemical stains were positive for AE1/AE3, Cam5.2, synaptophysin and TTF-1. The patient was transferred to a tertiary center for initiation of carboplatin/etoposide chemotherapy.

Discussion: Extrapulmonary SCCs represent approximately 2.5-5% of all SCCs. SCC of the prostate has an incidence of about 2%. The presence of SCC within the rectum is unusual, but when it occurs it typically presents as an ulcerative lesion. In our case, SCC of the rectum presented as an ulcerative lesion with luminal narrowing explaining both rectal pain and constipation. In adenocarcinoma of the prostate, rectal involvement is usually a rare result of seeding following transrectal prostate biopsy. The aggressive nature of SCC causes it to act much differently than adenocarcinoma, with rapid growth. Thus, a precipitous growth in prostatic tumor size could suggest a high grade malignancy such as SCC. In this setting, providers may want to exercise caution when contemplating transrectal biopsies and consider colorectal surveillance when patients complain of even subtle gastrointestinal symptoms.


Figure: Endoscopic visualization of malignant rectal ulceration.


Disclosures:
Matthew Everwine indicated no relevant financial relationships.
Summar Salim indicated no relevant financial relationships.
Wei Hong indicated no relevant financial relationships.
Richard Walters indicated no relevant financial relationships.


Matthew Everwine, DO¹, Summar Salim, DO², Wei Hong, MD³, Richard Walters, DO⁴. P1220 - A Prostatic Seeding Leading to an Uncommon Cause of Constipation, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.