Small cell carcinoma of the prostate presenting with skin metastasis: a case report

Small cell carcinoma of the prostate is a very rare and aggressive type of prostatic cancer. Most cases are diagnosed at advanced stage due to early metastasis. The bones, liver, regional and distant lymph nodes are the most common sites of metastasis of small cell carcinoma of the prostate. Skin metastasis of small cell carcinoma of the prostate is a very rare entity due to the uncommon metastatic site. Here, we describe the case of a patient with small cell carcinoma of the prostate which metastasized to his skin.

A 74-year-old Caucasian man presented to another urology center for mild lower urinary tract symptoms in 2003. His prostate-specific antigen was 23 ng/mL. According to the physical examination signs and prostate-specific antigen, he underwent a transrectal ultrasound-guided prostate biopsy. The pathologic examination of his prostate revealed a Gleason score: 3 + 4 = 7 adenocarcinoma of the prostate. Investigations showed stage T2N0M0 disease and he was treated with radiotherapy to his pelvic lymph nodes and prostate. Six years after the initial diagnosis, he complained of a palpable left-side 2 × 2 cm subcutaneous solitary mass localized just behind his scapula. The results of his laboratory tests including serum acid phosphatase and prostate-specific antigen were in normal ranges. Our general surgery department performed a diagnostic biopsy of the mass and totally excised the lesion. The pathologic examination of the mass showed small cell carcinoma metastasis with chromogranin + and the pathologist advised us to examine the lung or prostate for the primary tumor. The patient undertook a transrectal ultrasound-guided prostate biopsy and the pathologic result revealed small cell carcinoma within residual adenocarcinoma. We investigated the other sites for metastasis and restaging investigations showed a 1cm metastatic lesion in his liver. Our medical oncology department decided to treat him with combination chemotherapy with etoposide and cisplatin in six cycles; however, he died due to disseminated myocardial infarction before starting the fifth combination chemotherapy cycle.

Clinicians should keep in mind that early diagnosis of this disease is very difficult due to early metastatic spread of small cell carcinoma and lack of concordant elevation of prostate-specific antigen. There is no accepted standard treatment modality for this pathology and overall prognosis is poor.