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Prostate mucinous adenocarcinoma with signet ring cells (MC-SRC) is a rare morphologic variant of prostate cancer, with only 12 cases reported to date[1]. Diagnosis of this carcinoma requires that at least 25% of the tumor tissue should consist of an extracellular mucin pool[2]. In this report, we present a case of prostate prostate mucinous adenocarcinoma with signet ring cells.
Case Report
A 60-year-old male patient applied to our clinic with a complaint of having urinary frequency and dysuria, cover a period of about 8 months. The patient had been smoking two packs of cigarettes a day for 30 years, the serum level of total prostate-specific antigen (tPSA) was 1.36 ng/ml and the free prostate-specific antigen (fPSA) was 0.23 ng/ml. An ultrasonography (US) examination showed the prostate was 5.2 × 4.6 × 4.7 cm in size and residual urine was 110 ml. On digital rectal examination (DRE), the prostate was elastic and painless and rectoprostatic sulci were found to be prominent with no hardness. A X-ray chest film found no positive detection.
A cystoscopy examination and transurethral resection of the prostate (TURP) were performed under anesthesia. The left and right prostatic lobes protruded into the urethral cavity. No necrotic lesions were observed. The bladder was moderately trabeculated, with no signs of stones or tumors. The ureteral orifices were also normal and in position. Extensive transurethral resection of the prostate was performed, with specimens totaling 40 g. A considerable amount of mucinous gelatinous material was retrieved from the incised margin of the specimen.
On histopathological examination, sections of the TURP specimen showed foci that consisted of pools of mucin, some of which contained malignant prostate cells (Fig.1). Tumor cells had a hyperchromatic nucleus, and some of them had narrow eosinophilic cytoplasm. Large, hyperchromatic signet ring cells which had a vacuolized cytoplasm with a peripherally positioned nucleus were detected (Fig.2). Immunochemical studies with alcian blue and periodic acid schiff (PAS) staining both confirmed the presence of mucinous materials. Prostate specific antigen (PSA) immunoreactivity was detected, while carcinoembryonic antigen (CEA) was not observed in our case.
Mucin pool in fibromuscular stroma (H&E stain, × 100).
Signet ring cells (H&E stain, × 400).
After TURP, the patient had no evidence of disease development. A total of 50 Gy radiotherapy (25 × 2 Gy) was applied 3 months after operation. Approximately 6 months after operation, his serum PSA level was normal (1.10 ng/ml). Thoracoabdominal CT and bone scintigraphy were found to be normal.
Discussion
Prostate mucinous adenocarcinoma is a rare variant of prostate adenocarcinoma. According to the reported cases, mucinous adenocarcinomas can be divided into three groups, including mucinous carcinoma (MC), signet-ring carcinoma (SRCC), and MCSRC[3].
There are no obvious differences between the clinical features of MC and the ordinary acinar type of carcinoma of the prostate. MC can present with urinary obstruction (70.2%), hematuria (25.5%), and vesical irritability (17.0%). Of the patients with MC, 77.8% have elevated PSA levels, with a similar percentage (77.8%) responding to hormonal therapy[4]. This rare type of carcinoma may well be a variant of acinar adenocarcinoma of the prostate, with a similar clinical course[5].
SRCC is rare and can occur alone as well as with mucinous carcinoma. In primary signet ring cell carcinomas, signet ring cells do not usually include mucin. Signet ring cell carcinoma comprises approximately 30% of the tumor that showes slight degeneration from the effect of hormonal therapy. The prognosis of signet ring cell carcinoma is worse compared to mucinous carcinoma.[6].
MCSRC is the least common mucinous adenocarcinoma reported in the literature. Only 12 cases have been reported since the first case, which was published by Kubo et al[3,7]. in 1964. In the reported cases of MCSRC, DRE was normal in 45% of the cases which was higher than other mucinous carcinoma variants (MC 27%, SRCC 33%). While elevation of PSA levels had not been observed in MCSRC cases, it had been reported in MC (77%) and SRCC (33%) cases.111 In our patient, the diagnosis was made incidentally because DRE and PSA levels (tPSA: 1.36 ng/mL) were normal and the symptoms of urinary frequency and dysuria resembled those of BPH.
With regard to treatment, 77.8% of MC and 30% of SRCC responded to hormonal therapy, while MCSRC did not at all (0%)[1,4 For this reason, treatment options for MCSRC are restricted to radical prostatectomy or radiotherapy. Furthermore, there is no consensus in the literature as to which should be the standard treatment. In our case, because the patient rejected radical prostatectomy, a total of 50 Gy (25 × 2 Gy) radiotherapy was applied 3 months after operation.
MCSRC has the worst prognosis compared with other mucinous carcinoma variants. Fifty percent of the MC cases, 27% of the SRCC cases, and 16.7% of the MCSRC cases showed 3-year survival.131 Our patient has survived for 6 months after diagnosis, with a normal serum PSA level and bone scintigraphy.
In conclusion, MCSRC seems to be different from other mucinous carcinomas of the prostate, and has a worse prognosis. Although it is difficult to define an optimum treatment strategy for MCSRC of the prostate from the existing data, a suitable dose (25 × 2 Gy) of radiotherapy might improve prognosis.
- Received August 3, 2006.
- Accepted September 25, 2006.
- Copyright © 2006 by Tianjin Medical University Cancer Institute & Hospital and Springer
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