Virchows Arch (2003) 443:787–791 DOI 10.1007/s00428-003-0911-2 CASE REPORT Mauro G. Mastropasqua · Giancarlo Pruneri · Giuseppe Renne · Ottavio De Cobelli · Giuseppe Viale Basaloid cell carcinoma of the prostate. Case report and review of the literature Received: 25 June 2003 / Accepted: 9 September 2003 / Published online: 24 October 2003  Springer-Verlag 2003 Abstract We report on a case of malignant basal cell carcinoma of the prostate combined with a poorly differentiated conventional adenocarcinoma, infiltrating bilaterally the seminal vesicles and with lymph-node and distant metastases. Basal cell carcinoma represented the prevalent component of the tumour (80%), showed high mitotic activity, extensive perineural infiltration and vascular invasion and was immunoreactive for basal cell related antigens (high molecular weight cytokeratins 34bE12 and p63). Our data confirm previous observations that basal cell carcinoma represents an aggressive tumour with an adverse clinical outcome. Keywords Adenoid cystic carcinoma · Basaloid cell carcinoma · Prostate Introduction Malignant tumours arising from the basal cells of the prostatic glands are exceedingly rare [2, 4, 8, 22, 32], with only 20 cases (11 of which with complete clinico- pathological data) reported thus far [1, 3, 5, 10, 11, 14, 15, 16, 17, 18, 19, 26, 28, 31]. These tumours have been classified according to the prevalent pattern of growth as adenoid cystic carcinomas (ACC) or basaloid cell carci- nomas (BCC). ACC/BCC may occur in a pure form or, rarely, in combination with conventional adenocarcinoma [17, 25, 31]. ACC/BCC with a prominent adenoid cystic architecture usually behave indolently, while the occur- rence of an extensive basaloid pattern has been associated with a more aggressive disease [7]. We report on a case of a malignant basal cell tumour of the prostate with an exclusive basaloid pattern combined with a poorly differentiated conventional adenocarcino- ma, infiltrating bilaterally the seminal vesicles and with lymph-node and distant metastases. Our data re-empha- sise that ACC/BCC with prominent basaloid features are aggressive tumours, whose correct identification is mandatory for adequately planning clinical staging and treatment of the disease. Clinical history A 65-year-old Caucasian man suffering from nicturia and hypo- gastric pain was admitted to a general hospital. Due to a high prostate-specific antigen (PSA) serum level, prostatic biopsies were performed and a histological diagnosis of carcinoma, most probably of a urinary bladder origin, was rendered. Following cystoscopy and random biopsies, which did not reveal any bladder tumour, the patient was referred to the Division of Urology of the European Institute of Oncology for further evaluation. The serum PSA level was 8.5 ng/ml and the prostate was enlarged and firm on digital rectal examination. Additional prostatic biopsies were taken, leading to the diagnosis of basaloid cell carcinoma of the prostate. The patient underwent radical prostatectomy with pelvic lymphad- enectomy 1 month later. The histological examination of the resected prostate revealed a basaloid carcinoma combined with a poorly differentiated classical adenocarcinoma without clinically evident metastatic deposits at time of surgery (Gleason’s score 4+4=8; pT3bN1M0). A computed tomography scan performed in an outside hospital 8 months later revealed pulmonary and bone metastases, which were not biopsied. The patient is currently alive with disease 12 months after surgery. Materials and methods Prostatic biopsies and the resected prostate were fixed in 10% buffered formalin and embedded in paraffin. Sections 3-mm thick were stained with hematoxylin & eosin. Sections representative of the tumour were also stained with periodic acid Schiff (PAS) diastase and Alcian blue. Immunohistochemical reactions were M. G. Mastropasqua · G. Pruneri · G. Renne · G. Viale ( ) ) Division of Pathology and Laboratory Medicine, European Institute of Oncology, Via Ripamonti 435, 20141 Milan, Italy e-mail: giuseppe.viale@ieo.it Tel.: +39-08-057489419 Fax: +39-08-057489417 M. G. Mastropasqua · G. Pruneri · G. Renne · G. Viale School of Medicine, University of Milan, Milan, Italy O. De Cobelli Division of Urology, European Institute of Oncology, Milan, Italy