Malignant Priapism Secondary to Metastatic Prostate Cancer: A Case Report and Review of Literature

Abstract

Penile metastasis of cancers from other primary sites is a rare phenomenon that infrequently manifests as malignant priapism. We outline a case of an 84-year-old patient who presented with a 3-month history of painful priapism after radiation therapy for prostate adenocarcinoma. The patient underwent surgical penile exploration and cavernosal biopsy that revealed poorly differentiated cells suggestive of prostate cancer. Postoperative imaging demonstrated extensive regional and distal metastases. A review of the literature on penile metastases returned approximately 400 published cases, with priapism being the initial presentation in 20% to 50% of cases. Regardless of site of origin or subsequent management, most cases have shown very poor prognosis.

Malignant priapism is a term first used by Peacock in 1938 to describe persistent, nonsexual erections caused by invasion of malignant cells into the cavernosal sinuses and their associated venous systems.¹ Several more mechanisms of priapism secondary to malignancy have been postulated and described. Metastatic penile disease has historically been a rare event, mostly found to be originating from pelvic primary sites. Clinical manifestations of penile metastases vary widely, and include penile nodules, cutaneous findings, and priapism.² We describe an interesting case of malignant priapism secondary to penile metastasis following radiation treatment for prostate carcinoma, review current literature on penile metastases and malignant priapism, and discuss the frequency, pathophysiology, mechanism, and prognosis of the disease process.

Case Report

An 84-year-old man with diabetes and a known diagnosis of prostate cancer presented with a 3-month history of persistent erection that began when he finished radiation treatment. The patient was first diagnosed approximately 3 months prior to current presentation with locally advanced, high-grade prostate cancer with a Gleason 4 + 5 component. He had undergone radiation treatment, after which he noticed the onset of persistent erection that was constant and painful. The patient reported sharp and burning pain that was only mildly relieved by topical lidocaine gel. A Winter shunt for detumescence had been attempted at an outside facility 6 weeks earlier, but the procedure provided no significant improvement in symptoms. Similarly, phenylephrine treatment was attempted to no avail. The patient continued to have constant penile pain and erection. A magnetic resonance imaging scan of the penis was performed at the time of the previous procedure which demonstrated possible partial cavernosal thrombosis at the base of the cavernosa as well as plaques within the tunica albuginea. On physical examination, the patient had a rigid penile shaft and glans, with pain on palpation. There were no palpable nodules and no overlying skin necrosis of the glans. There was also decreased sensation along the shaft. Penile ultrasound at this time demonstrated flow of 15 mL/s. Given the urgency of the presentation, the patient underwent surgical repair of priapism and penile exploration. During the procedure, a cavernostomy did not demonstrate any significant amount of bleeding, raising concerns for a nonvascular etiology of the priapism. Further exploration demonstrated an extensive amount of fibrosis and necrosis of each of the cavernosal bodies. Intraoperative biopsies of the corpus cavernosa revealed adenocarcinoma consistent with metastatic prostate cancer. Postoperatively, the patient continued to complain of decreased penile sensation. A bone scan demonstrated metastases to the pelvic region, and computer tomography images showed metastatic disease in left lower lung, liver, and abdominal and pelvic lymph nodes. The patient and family were counseled extensively on the extent of his disease as well as treatment options. He was then referred to oncology for further medical management and palliative treatment.

Discussion

Secondary penile lesions are a rare phenomenon, first described in 1870 by Eberth. Reviews of published case reports reveal that organs along the genitourinary tract, such as the prostate and bladder, are the most common primary sites.² Cherian and colleagues compiled a review of published cases of secondary penile tumors up to September 2006, listing a total of 372 primary site-specific cases of metastatic penile lesions.³ Using a PubMed literature search for published human cases with English abstracts and the keywords “penile metastasis”, “penile metastases”, “malignant priapism”, and “secondary” AND “malignancy” AND “penis”, we present here an updated listing of the reported cases of metastatic lesions to the penis published since September 2006 (Table 1). In our extensive search we tabulated 29 published case reports of penile metastases since September 2006,^8–35 including our present case. Building on the data from Cherian and associates, there are a total of 394 published cases of secondary penile malignancies to date. Of note, Zheng and colleagues found 22 cases of primary lung cancers metastasizing to the penis, a much higher count than that of Cherian and colleagues.²⁶ Of the 394 documented cases, 129 (33%) cases were of prostate origin, and bladder cancer was a close second with 118 published cases (30%). Interestingly, Chan and coauthors report that the true incidence of penile metastasis may be higher than that recorded, given that 12% of penile metastasis may be asymptomatic and discovered only on autopsy. Furthermore, unpublished cases were not accounted for during a review based on the literature search.²

Table 1.

Primary Sites of Penile Metastases Discussed in Published Reports Since September 2006³

Primary Site	New Cases Since Sept 2006	Total Cases (%)
Prostate	4	129 (33)
Bladder	6	118 (30)
Recto-sigmoid	6	54 (14)
Kidney	–	30 (8)
Lower GI tract
(excluding recto-sigmoid)	1	16 (4)
Testis	1	12 (3)
Lung	3	7a (2)
Upper airway	–	4 (1)
Upper GI tract	3 (esophagus 3)	6 (2)
Bone	–	3 (0.8)
Ureter	–	2 (0.5)
Hepatobiliary	–	2 (0.5)
Other	5 (glomangiosarcoma 1,	11 (3)
	melanoma 1, lymphoma 2,
	seminal vesicle 1)
Total	29	394

^aAn extensive search by Zheng and colleagues in August 2008 revealed 22 total cases of penile metastases from lung.²⁶

GI, gastrointestinal.

Clinical manifestations of penile metastases include penile masses or nodules, ulceration, obstructive or irritative urinary symptoms, hematuria, and malignant priapism in 20% to 50% of the documented cases.^2,4 Initial symptoms and the presence or absence of priapism in the 28 published cases since September 2006 are presented in Table 2. As was previously described, 7 of the 29 cases (24%), including the present case, presented with priapism.^8–35 Different mechanisms of persistent erection due to malignancy have been described, with a distinction between low-flow and high-flow priapism. Most incidences of malignant priapism are considered to be low-flow priapisms and are believed to be due to neoplastic invasions into the cavernous sinuses and venous system, causing a complete blockage and a consequent unrelenting erection. Other low-flow mechanisms include venous stasis and/or thrombosis with possible nervous system disturbances. In a case of metastatic bladder cancer presenting with malignant priapism in 1998, Dubocq and colleagues described the possibility of priapism secondary to high flow in the cavernosal arteries with reversal of flow during diastole. Dubocq also described Doppler ultrasound and blood gases as confirmatory studies in the distinction of the two types of priapism. For all malignant priapisms, however, corporal biopsies are considered the most direct method of evaluating the underlying cause and the primary site of neoplasm.¹

Table 2.

Cases of Penile Metastases Discussed in Published Reports Since September 2006³

Primary Site	Investigator	Histopathology	Initial Symptoms	Priapism	Survival (mo)
Prostate	Rohan V et al (2009)8	Prostate adenocarcinoma	Inguinal lymphadenopathy	−	>14
	Cai T et al (2007)9	Prostate adenocarcinoma	Painful erythematous glans nodules	−	20
	Cortés González JR et al	Prostate adenocarcinoma	Painless penile nodules	−
	(2006)10
Bladder	Egufluz Lumbreras P et al	Transition cell carcinoma	Hematuria	+	>4
	(2009)11
	Santos Gda C et al (2009)12	Transition cell carcinoma	Palpable penile nodule	−
	Hadzi-Djokić J et al (2009)13	Transition cell carcinoma		−	>10
	Barresi V et al (2009)14	Microcystic urothelial carcinoma		−	6
	Sari A et al (2007)15	Microcystic urothelial carcinoma	Hematuria, glans ulceration	−	6
	Celma Domènech A et al	Transition cell carcinoma	Priapism	+
	(2009)16
Rectum	Park JC et al (2009)17	Rectum adenocarcinoma	Priapism, penile nodules	+
	Küronya Z et al (2009)18	Rectum adenocarcinoma		−
	Chung TS et al (2008)19	Rectum adenocarcinoma	Penile nodules	−	> 6
	Murhekar KM et al (2007)20	Rectum adenocarcinoma	Phymosis, indurated glans lesions	−	> 2
	Ketata S et al (2007)21	Rectum adenocarcinoma		−
	Añibarro Laca E	Rectum adenocarcinoma	Painful penile swelling	−
	et al (2006)22
Lower GI	Ozawa H et al (2009)23	Cecum adenocarcinoma	Penile pain	−	26
Testis	Jiang H et al (2009)24	Testis mixed germ cell tumor	Priapism	+	10
Lung	Haliloglu AH et al (2009)25	Lung malignant epithelial tumor	Erectile dysfunction, palpable nodule	−
	Zheng FF et al (2009)26	Lung adenocarcinoma	Perineal and penile swelling, glans ulcer	−	2
	Sofikerim M et al (2007)27	Lung epidermoid carcinoma	Painful erections, penile nodule,	−
			difficulty voiding
Esophagus	López-Aramburu MA	Esophagus tumor thrombosis	Painful necrotic skin over penis	−	3
	et al (2009)28
	Pai A et al (2008)29	Esophagus squamous carcinoma	Painful perineal and penile nodules	−	> 6
	Numakura K et al (2008)30	Esophagus squamous carcinoma	Penile pain, penile nodules, dysuria	−	3
Lymphoma	Gallardo F et al (2009)31	Large B-cell lymphoma	Penile nodules, paraphymosis, glans	−	>30
			swelling
	Lan SK et al (2008)32	Nasal NK/T-cell lymphoma	Painful penile nodule	−	>4
Glomangiosarcoma	Masson-Lecomte A	Pulmonary and cardiac	Priapism	+	>10
	et al (2009)33	glomangiosarcoma
Seminal vesicle	Thyavihally YB	Mucin secreting papillary	Acute urinary retention, painful	−	6
	et al (2007)34	adenocarcinoma	penile swelling
Melanoma	Okinami T et al (2009)35	Malignant melanoma	Priapism, dysuria	+

GI, gastrointesinal; NK, natural killer.

As in our patient, prostate cancer is among the most common primary malignancies to metastasize to the penis, usually via venous spread, lymphatic invasion, and direct extension.⁵ Venous spread remains the most likely mechanism of metastasis and is explained by the rich communication between the dorsal penile venous system and the pelvic organs. Reversal of flow due to neoplastic invasion or compression can further facilitate the process. Lymphatic spread is thought to occur in a similar fashion. Direct extension is generally observed in rigorously invasive tumors originating in sites of close approximation to the penis, including prostate, bladder, and rectum. The possibility of arterial spread has been proposed as well.³

Regardless of mechanism of spread or site of primary cancer, the prognosis of secondary penile malignancies is generally poor. It is reported that the average survival of such patients is approximately 9 months, with an overall survival of less than 18 months.^4–6 In one case report, a near 100% mortality rate was described.⁷ The longest reported cases of survival have been 7 and 9 years.⁴ In the 29 cases we reviewed in the present report, a majority of the patients (11/18) with follow-up data died within 6 months.^8–35 The longest survival time was 30 months for a patient with large B-cell lymphoma.³¹ Treatment of secondary penile lesions with malignant priapism has generally been aimed at palliation and improved quality of life, including surgical management of priapism and a possibility of penectomy for cutaneous lesions, urinary symptoms, and pain.^1–7

Conclusions

Penile metastasis of cancers from other primary sites is an extremely rare phenomenon and only infrequently does it present itself as malignant priapism. Literature review reveals approximately 400 published cases of secondary penile malignancies, one-third of which are of prostatic origin. It has been reported that 20% to 50% of penile metastases present with priapism. Malignant priapism can be distinguished between high flow or low flow via Doppler ultrasound, and different mechanisms of metastases to the penis have been proposed. However, regardless of mechanism of spread, the prognoses for secondary penile malignancies are grim, with the majority of patients surviving less than 18 months.

Main Points.

• Described here is a patient with metastatic prostate adenocarcinoma presenting with painful priapism. Literature review reveals approximately 400 published cases of secondary penile malignancies, one-third of which are of prostatic origin.

• Clinical manifestations of penile metastases include penile masses or nodules, ulceration, obstructive or irritative urinary symptoms, hematuria, and malignant priapism in 20% to 50% of the documented cases.

• Malignant priapism can be distinguished between high flow or low flow via Doppler ultrasound, and different mechanisms of metastases to the penis have been proposed. Most incidences are considered to be low flow and are believed to be due to neoplastic invasions into the cavernous sinuses and venous system, causing a complete blockage and a consequent unrelenting erection.

• Regardless of mechanism of spread or site of primary cancer, the prognosis of secondary penile malignancies is poor. The average survival is approximately 9 months with an overall survival of less than 18 months.