Case report: Subcutaneous metastasis from small cell carcinoma of the prostate

Mustafa Kaplan1, Irfan H. Atakan1, Selcuk Bilgi2 & Osman Inci11Department of Urology, 2Department of Pathology, Trakya University, Faculty of Medicine, Edirne, Turkey

Abstract. Pure primary small cell carcinoma of the prostate (SCCP) is an extremely rare entity. Naturalhistory of this tumor is similar to that of the bronchogenic small cell carcinoma. Several theories ofhistogenesis have been proposed. Most widely accepted view is that SCCP arises from pluripotent stem cellsof the prostate, which have the ability to differentiate into either epithelial or neuroendocrine type carci-nomas. SCCP has an aggressive course, and a majority of patients have distant metastasis at presentation.Since it is a rare entity, no standard treatment regimen has been established. A case of primary pure SCCPwith multiple subcutaneous metastases is presented.

Key words: Small cell carcinoma, Subcutaneous metastasis, Prostate

Introduction

Small cell carcinoma of the prostate (SCCP) is arare and lethal disease. In a review of the litera-ture, 33 reported cases of small cell carcinoma ofthe prostate were noted, of which 13 had puresmall cell carcinoma [1]. Histologic features andclinical behavior of this tumor are similar tothose of bronchogenic small cell carcinoma.SCCP has an aggressive course and metastasizerapidly to distal lymph nodes, lung, liver, brainand soft tissues. Although the optimal treatmentmethod is chemotherapy, the median survival is5.2 months [2]. The incidence of subcutaneousmetastasis from SCCP is unknown. We havepresented a rare and lethal pure SCCP withsubcutaneous metastases, and aimed to review theliterature data.

Case report

A 68-year-old man was admitted to our clinic withcomplaints of urinary retention, nausea, vomitingand multiple subcutaneous nodules on the anteriorchest and abdomen (Figure 1) in March 2004.His serum urea nitrogen and creatinine level waselevated (221 mg and 14.2 mg respectively).The results of liver function tests were normal.Ultrasound examination revealed bilateral grade II

hydronephrosis. Digital rectal examinationrevealed a large prostate especially left lobe andtransrectal ultrasonograpy (TRUS) demonstrateda prostate (81 cc) with heterogeneous echogenity.A CT scan of the pelvis showed enlargement of theprostate with extension to the bladder (Figure 2).A TRUS guided biopsy (Figure 3) and subcuta-neous tissue biopsy (Figure 4) was performed.Results of the pathologic examination of the tissuesamples were SCCP. The tumor cells were smallwith scant cytoplasm and had hyper chromaticnuclei. Immunohistochemically the tumor cellswere negative for PSA, and chromogranin A wasweakly positive. The serum PSA was 2.07 ng/ml.Plain film of chest was normal. Bone scintigraphyshowed no abnormalities. He refused additionalworkup and complete treatment, and died after2 months in May 2004.

Discussion

Small cell carcinoma arising from extra-pulmo-nary sites represents 2 to 4% of all small cell car-cinomas. The most common sites of origin includegynecologic organs, particularly the cervix; thegastrointestinal tract, particularly esophagus andcolon; the upper airway; sinuses and salivaryglands; and genitourinary glands, particularly the

International Urology and Nephrology (2007) 39:157–160 � Springer 2007DOI 10.1007/s11255-005-3620-8

prostate [3]. Almost all patients have distantmetastasis at the time of diagnosis. The most fre-quent sites of metastases are distal lymph nodes,lung, liver, brain, and soft tissues. Bone metastasisis not common. However, a few case of SCCP,which metastasized to pubic bone [3], and tempo-ral bone [2], have been reported recently. Omen-tum, vocal cord, peri-adrenal soft tissue and

adrenal gland metastases are also reported [2, 4].Extra-pulmonary small cell carcinoma arising inthe prostate has been described in several caseseries and case reports [2–5]. Median survival forSCCP is 5.2 months [2].

Histologically, the small cell variant of pros-tatic carcinoma is distinct from adenocarcinoma.Three theories of histogenesis have been proposed.

Figure 1. Multiple subcutaneous nodules on the anterior chest and abdomen.

Figure 2. Computerized tomography showing enlargement of the prostate with extension to the bladder.

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One theory suggests that according to immuno-histochemical and electron microscopic studiesSCCP arises from cells in the prostatic epitheliumthat have dual capacity for differentiation intoadenocarcinoma and small cell carcinoma [4]. Ithas been suggested by some authors that SCCP isderived specifically from the argyrophil andargentaffin cells normally within the prostate [6].Some authors have hypothesized that both tumor

types arise from a pluripotent stem cell that is ableto differentiate into both a mature prostaticepithelial cell and a neuroendocrine cell [7]. Themost accepted theory is the last one.

In contrast to prostatic adenocarcinoma, PSAis an unreliable tumor marker for SCCP and isusually normal. Rubenstein et al. suggest thatcarcinoembryonic antigen is a more reliable marker[4].

Figure 3. Small cell carcinoma in prostatic tissue with focal necrosis (H&E�50).

Figure 4. Metastasis of small cell carcinoma in subcutaneous tissue (H&E�200).

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Small cell carcinoma of the prostate respondspoorly to hormone treatment [8]. This is not sur-prising, because the SCCP do not express androgenreceptors. SCCP is sensitive to a chemotherapyregimen used for bronchogenic small cell carci-noma [9, 10]. Despite treatment with chemother-apy, the prognosis of SCCP is extremely poor. Dueto the rarity of the condition, no standard thera-peutic regimen has been developed.

Conclusion

SCCP is a highly aggressive tumor that metasta-sizes rapidly and has a poor prognosis. Earlydiagnosis is difficult since PSA is usually normal.Clinical course and presentation of SCCP aresimilar to small cell cancer of the lung.

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Address for correspondence: Mustafa Kaplan, Avrupa Kent

Yapi Kooperatifi, Iskenderkoy Mevkii, B7-4, Edirne 22030,

Turkey

Phone: +00-90-284-235-27-32; Fax: +00-90-284-235-27-30

E-mail: mustafakaplan99@hotmail.com

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