Isolated Testicular Metastasis from Prostatic Adenocarcinoma

Abstract

Metastatic carcinomas to the testes are rare with prostate adenocarcinoma being the most common. Reported cases of metastatic carcinoma to the testes are usually associated with metastasis to other sites. Metastasis to the testis alone without associated secondaries to other sites can occur and so far, few cases have been reported globally. Due to the rarity of such presentation and the need for proper evaluation of orchiectomy specimens for prostatic adenocarcinoma, we report a case of an 84-year-old with isolated metastasis to the left testes. This was discovered incidentally the following orchiectomy as a form of hormonal therapy for prostatic adenocarcinoma.

INTRODUCTION

Metastatic carcinoma to the testes was first reported in the United States of America in 1938 and up until 2006, fewer than 200 cases have been reported globally.[1] In Nigeria, three cases of metastatic carcinoma to the testes have so far been documented in the southern parts of the country following review of testicular tumors.[2,3] Metastatic carcinomas to the testes are rare with large autopsy series reporting an incidence of 0.06%.[4] Common tumors metastasizing to the testes in adults are tumors of the prostate, lungs, gastrointestinal tract, melanomas, and kidneys.[5,6] Of these tumors, prostate adenocarcinoma is by far the most common tumor metastasizing to the testis in adults.[7] Majority of the reports on testicular metastasis from prostatic adenocarcinoma have shown coexistence with metastasis to other sites. However, a few authors reported isolated testicular metastasis from prostatic adenocarcinoma.[8] We report a rare case of an isolated unilateral testicular metastasis from prostatic adenocarcinoma incidentally discovered following bilateral orchiectomy as part of hormonal treatment in an 84-year-old man with prostatic adenocarcinoma. This is aimed to add to the few cases so far reported and to emphasize the need for proper evaluation of testes and paratesticular structures to exclude metastasis.

CASE REPORT

An 82-year-old, presented with irritative and obstructive lower urinary tract symptoms for 1 year. He had no other systemic symptoms or symptoms suggestive of metastasis. Digital rectal examination revealed a hard, nodular, and asymmetrically enlarged prostate. Other system examinations were all normal. Serum prostate-specific antigen (PSA) was 25.78 ng/mL. Prostatic ultrasound shows an enlarged suspicious prostate with heterogeneous echo pattern; the prostatic capsule was irregular with obliterated median groove. Chest and lumbosacral X-rays did not show evidence of metastasis as an abdominal ultrasound scan was also normal. Tru-cut biopsy of the prostate gland reported prostatic adenocarcinoma with Gleason 2 + 3 [Figure 1]. He was counseled and offered bilateral sub capsular orchiectomy as a form of androgen deprivation therapy. Grossly, the left testis was fairly circumscribed and measure 4.5 cm × 3.5 cm × 2 cm cut surfaces were gray white-to-brown. The right testicular biopsy was a spongy tissue flap measuring 7 cm × 6 cm × 2 cm. Microscopically, the left testis showed infiltrating acini and glands lined by a single layer of atypical cells having hyperchromatic nuclei, infiltrating ghost of atrophied seminiferous tubules [Figure 2]. The right testis showed seminiferous tubules containing cells of spermatogenic series at different stages of maturation having mildly hyalinized basement membranes. Foci of unremarkable interstitial cells of Leydig were also present. A diagnosis of the left testicular metastatic adenocarcinoma from prostatic adenocarcinoma with the right unremarkable testis was made.

Figure 1.

Prostatic core showing infiltrating malignant glands

Figure 2.

Photomicrographs showing metastatic testicular carcinoma. Note the infiltrating glands and the atrophied seminiferous tubules

DISCUSSION

Prostatic cancer is one of the most common cancer in men and the most common primary malignancy that metastasize to the testis. Secondaries to the testis from prostatic adenocarcinoma are usually seen in the sixth and seventh decade, unlike primary testicular tumors which presents at relatively young age. The case reported is an 84-year-old and was diagnosed with adenocarcinoma of the prostate before the orchiectomy. In consonance with the observation in the index patient, studies have shown that metastatic tumor to the testis is usually unilateral and are discovered incidentally during autopsy or after therapeutic orchiectomies with some even presenting several years after prostatectomy.[9,10] However some patients may present with scrotal swelling and pain.

The mechanism of spread for prostatic carcinoma to the testis is not fully understood; however, suggested mechanisms include as follows: retrograde venous extension, arterial embolism, lymphatic extension, and endocanalicular spread.[11] In cases of testicular metastasis coexisting with bony or visceral metastasis, a hematogenous pattern of spread can be speculated. The index case, the lymphatic extension is perhaps the mechanism of spread due to the unique lymphatic connection between the prostate and the testis and the absence of other metastatic deposit. The microscopic morphology of metastatic disease affecting the testicle usually affects the interstitium, sparing the seminiferous tubules. Occasionally, atrophic seminiferous tubules may, however, be partially or completely invaded. These features were all demonstrated in the index case.

Most cases of prostatic carcinoma metastasizing to the testis are usually advanced. They are associated with multiple metastatic deposits and high Gleason score of ≥8. Few reported cases of isolated testicular metastasis from the prostate also have reported high Gleason score of ≥8. On the contrary, the index case had an isolated testicular metastasis from prostatic carcinoma but with a Gleason score of 5.

The entire clinical workup for this patient did not suggest metastasis to any site. Bone scintigraphy would have been more ideal to exclude bone metastasis; however, it is not available in our center and X-ray is used instead. The chest and lumbosacral region are common sites for secondaries form prostatic adenocarcinomas. X-rays of these regions have so far been worthy for patients presenting with advanced disease.

The prognostic value of testicular metastasis from prostatic carcinoma has been investigated in some few publications. Some have suggested that it portends poor prognosis, while some other authors have reported otherwise. The prognostic value of testicular metastasis from prostatic carcinoma has been investigated in some few publications. Some have suggested that it portends poor prognosis. However, some authors have reported otherwise, in a particular report of an isolated testicular metastasis from prostatic carcinoma patient had >5 years disease-free interval with undetectable PSA levels after orchiectomy.[12] The prognostic value of testicular metastasis from prostatic carcinoma need to be evaluated further putting in to consideration confounding factors.

CONCLUSION

Testicular metastasis is very rare with prostatic cancer as the most common primary malignancy. Proper physical examination through specimen sampling and imaging of all the possible sites of metastasis are indispensable in the process of identifying metastasis.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.