Metastatic prostate adenocarcinoma and high-grade appendiceal mucinous neoplasm mimicking acute appendicitis in a post-radiation therapy patient

Abstract

Prostate cancer is the most common visceral malignancy diagnosed in males. Surveillance for post-treatment neoplasms is very crucial. Here we report the first case of recurrent metastatic prostate cancer presenting as acute appendicitis in a background of a high-grade appendiceal mucinous neoplasm. In addition, this case also includes an unusually early presentation of a secondary primary malignancy after radiation therapy. A 70-year-old male with a history of prostate adenocarcinoma status post-proton radiation therapy presented with recurrent poorly differentiated prostate adenocarcinoma with disease progression and extra-prostatic extension. He underwent salvage proton therapy and testosterone replacement therapy. Two years later, the patient presented with right lower quadrant pain. A computed tomography scan showed perforated acute appendicitis with intra-abdominal abscess, which was treated with interval appendectomy. Upon histologic analysis, metastatic prostatic adenocarcinoma was noted in the appendiceal wall and mesoappendix. In addition, an incidental background of high-grade appendiceal mucinous neoplasm was found. Four months later, he presented with persistent abdominal pain, rapid weight loss, fatigue, and fever for 3 months. An abdominal CT scan revealed a 6.1 cm rectal mass. Pathologic analysis diagnosed an aggressive post-radiation spindle cell sarcoma, intermediate to high grade. The patient opted for palliative care. This case shows that a clinical presentation of acute appendicitis in an older patient may sometimes portend a neoplastic rather than infectious etiology. Clinical history and patient epidemiology should always be considered when evaluating an older patient with clinical signs and symptoms of acute appendicitis.

Prostate cancer metastasis mimicking appendicitis—A rare but important differential diagnosis in PET/CT imaging

“…Only a small percentage of disseminated prostate cancer shows metastasis in the digestive system or the peritoneum, [1] and even more uncommonly carcinomatosis in relation to the appendix. In all previously reported cases of prostatic metastasis in the appendix, the patients presented with acute appendicitis and had an appendectomy performed from which metastasis was confirmed through histopathological assessment of the surgical specimen [ [2] , [3] , [4] , [5] , [6] , [7] , [8] , [9] , [10] , [11] ]. Acute appendicitis is found to be the most frequent initial manifestation of appendiceal tumors, seen in 30%-50% of patients [15] .…”

“…These image findings could equally come as a result of the extension of the metastasis or from a superimposed appendicitis [15] . Preoperative CT scans from previously reported cases of acute appendicitis secondary to prostate cancer metastasis predominantly show dilated appendix, periappendicular stranding and/or wall thickening [ 2 , [3] , [4] , [5] , [6] , 7 , [8] , [9] , [10] ]. Christou et al present a patient with an identical initial staging and Gleason score to the patient in the present report [2] .…”

“…Carcinomatosis in relation to the appendix is even more uncommon and not well described in the literature. To the best of our knowledge, only 11 cases of prostate cancer with a metastatic affinity for the appendiceal tissue have been reported worldwide, all located in the appendiceal lumen [ [2] , [3] , [4] , [5] , [6] , [7] , [8] , [9] , [10] , [11] ].…”

Acute Appendicitis Secondary to Metastatic Malignancy - A Review of 78 Cases in Literature

“…For example, in one of our cases, a 70-year-old male with history of T3N1M0 Gleason 7 prostatic adenocarcinoma presented with contained perforated appendicitis and was managed conservatively with iv antibiotics. Six weeks later he represented with a symptomatic appendiceal mucocele with histology showing metastatic prostatic adenocarcinoma infiltration [60].…”

“…Eight cases of metastatic prostate cancer resulting in acute appendicitis were found [54][55][56][57][58][59][60][61]. Patients ranged from 62 to 82 years old, with a mean age of 80 years old.…”