15018752330
发表时间:2015-11-24 浏览次数:472次
Introduction
Prostate cancer is the most common male malignancy in the world with an estimated 1,100,000 new cases and 307,000 cancer-related deaths in 2012. Although most prostate cancer patients have localized disease with a favorable prognosis, advanced prostatic cancer metastasize frequently to the bone and regional lymph nodes, but prostate cancer metastasis to the omentum with malignant ascites is very rare.In this study, we report such a rare case.
Case Report
A 65-year-old man was initially diagnosed as prostate adenocarcinoma
with Gleason score 7 (4 + 3 = 7 out 10) in 2004. The level of prostatic
specific antigen (PSA) was 233 ng/mL at cancer diagnosis. He then
underwent bilateral orchiectomy and hormonal therapy with 50 mg dose of
bicalutamide, but discontinued after 5 months treatment. In 2009, his
PSA level raised to 90 ng/mL, but there was no evidence of metastasis
detected by either computed tomography (CT) or bone scan. He was again
on bicalutamide treatment, but his PSA response lasted for approximately
2 years. In December 2011, bicalutamide treatment was discontinued, and
Fosfestrol was started. However, in November 2013, his PSA level was
increasing to 27.4 ng/mL and therefore, fosfestrol was discontinued and
the patients were treated with ketoconazole and prednisolone.
One
month after this regime of treatment, patient presented with 10 days
history of abdominal distension and found to have gross ascites. A
diagnostic and therapeutic paracentesis was conducted and removed 1,500
mL straw colored fluid. Fluid analysis showed to be exudate and cytology
was negative for malignant cells. Ascitic fluid adenodeaminse titer and
polymerase chain reaction showed negative for tuberculosis. Ascetic
fluid was taken and tested for multiple times, but all were negative.
Moreover, esophageal-gastrodudenoscopy and colonoscopy were normal.
Contrast-enhanced CT abdomen in March 2014 showed prostatic mass with
gross ascites with thickened omentum [Figure 1].
Bone scan shows no evidence of skeletal metastasis. Serum and ascitic
PSA were 316 ng/mL and 175 ng/mL, respectively. A ultrasound-guided
biopsy of the thickened omentum and histology showed a metastatic
adenocarcinoma [Figure 2], which was immunohistochemically positive for cytokeratin (CK) and PSA [Figure 3] and focally positive for CK7, whereas negative for CK2. Patient was then planned for Taxotere-based chemotherapy.
Discussion
Although prostate cancer can metastasize to nearly any organs in the body, metastasis without osseous involvement is extremely rare. Arnheim showed in 1948 that in 176 postmortem cases, the bone, lymph nodes, and lungs were the most common metastasis of prostate cancer, whereas the uncommon metastasis sites included the adrenal gland, kidney, brain, pancreas, genitalia, and breast. Malignant effusion, whether pleural or peritoneal, was an extremely rare. Moreover, Rapoport and Omenn reviewed the autopsy of 523 prostate cancer cases and found that 13 cases had peritoneal deposits, but with no other metastasis elsewhere in the body, indicating that there were effusions occurring in prostate cancer patients without any involvements of the more common metastatic sites. Thus, if other benign (like tuberculosis in India) and malignant (especially gastrointestinal) etiologies should be excluded, these patients could reasonably be thought to be due to prostate cancer-induced ascites. Until date, there have been only 16 published cases of malignant ascites in prostate cancer and most cases presenting with malignant ascites were associated with other metastatic sites, including the bone, lymph nodes, omentum, rectal wall, liver, adrenal, and pleural effusions.
The mechanism of malignant ascites may include peritoneal seedlings or lymphatic obstruction. Tumor cells in an effusion may have exfoliated from the primary lesion as evidenced by the positive cytology after repeated cytological examinations of ascetic fluid. However, negative cytology could be very difficult to make a differential diagnosis between benign and malignant ascites, such as the current case. The immunohistochemical staining can provide a valuable adjunction. For example, immunostaining of prostatic acid phosphatase and/or prostate specific antigen could be useful in the diagnosis of prostate cancer with a malignant effusion. Usually, malignant effusions in prostate cancer patients are associated with very poorer prognosis.
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