Penile metastases of rectal adenocarcinoma

Penile metastases are very rare and arise most frequently from genitourinary cancers. Penile metastases from rectal adenocarcinoma are less common and only 50 or so cases have been reported.

We present a 43-year-old man with penile metastases from a rectal adenocarcinoma. Two years before admittance to our department, abdomino-perineal resection of the rectum (Miles operation) was performed for a Dukes B (T3N0M0) rectal adenocarcinoma; the surgical resection margins wee negative. Adjuvant chemotherapy and radiotherapy treatment were administered. One year after initial management, excision of a local recurrence was performed followed by further chemotherapy. The patient subsequently noticed lesions of the penis measuring up to 1.2 cm in diameter. Biopsy revealed metastatic adenocarcinoma. Computed tomography showed normal structure of penis with subcutaneous nodular thickening. Soon thereafter, the entire shaft of the penis becomes indurated and the patient developed urinary obstruction. A suprapubic cystostomy was performed. The patient died within 6 months.

Penile metastases arise most frequently from genitourinary cancers, primarily from the bladder and the prostate gland. Metastasis to the penis from a rectal adenocarcinoma occurs much less commonly. Other reported primary origins of penile metastases include malignancies of the lung, nasopharynx and melanoma. The major symptoms are penile nodular mass, malignant priapism, penile pain and tenderness, difficulty in micturition, and urinary retention. Possible routes of metastasis are arterial, retrograde venous spread, retrograde lymphatic spread, but direct tumor infiltration/extension is also possible. Penile metastases from rectal adenocarcinoma usually occur within 2 years after diagnosis of the primary tumor. The prognosis is very poor regardless of treatment modality. Treatment is more often palliative than curative. Survival usually varies from 7 months to 2 years. Long-term survival (9 years) has been seen after aggressive surgical treatment (penile amputation) with best results for patients when penile metastasis was the only evident region of recurrence.

The prognosis of metastasis to the penis is very poor; the best results have been achieved with surgery but only for lesions where metastasis is limited to the penis.