© 2008 THE AUTHORS JOURNAL COMPILATION © 2 0 0 8 B J U I N T E R N A T I O N A L | 1 0 2 , 1 3 6 9 – 1 3 7 4 | doi:10.1111/j.1464-410X.2008.08074.x 1369 2008 THE AUTHORS. JOURNAL COMPILATION 2008 BJU INTERNATIONAL Mini Review UNUSUAL CARCINOMAS OF THE PROSTATE MAZZUCCHELLI et al. Rare and unusual histological variants of prostatic carcinoma: clinical significance Roberta Mazzucchelli, Antonio Lopez-Beltran*, Liang Cheng † , Marina Scarpelli, Ziya Kirkali ‡ and Rodolfo Montironi Section of Pathological Anatomy, Polytechnic University of the Marche Region, School of Medicine, United Hospitals, Ancona, Italy, *Department of Pathology, Reina Sofia University Hospital and Faculty of Medicine, Cordoba, Spain, † Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, IN, USA, and ‡ Department of Urology, School of Medicine, Dokuz Eylül University, Izmir, Turkey Accepted for publication 14 May 2008 that originate in the prostate. Some develop from acinar adenocarcinoma after hormonal or radiation therapy. They are usually aggressive tumours that often present with secondary deposits. The outcome is generally poor. Only basal cell carcinoma is seen as a low-grade carcinoma. KEYWORDS small cell carcinoma, ductal adenocarcinoma, carcinosarcoma, unusual carcinomas We review the clinicopathological features of the following unusual histological variants of prostatic carcinoma: small cell carcinoma, ductal adenocarcinoma, sarcomatoid (carcinosarcoma), basal cell, squamous cell and adenosquamous, and urothelial carcinoma. These variants are rare and account for 5–10% of carcinomas INTRODUCTION Prostate cancer is the most common cancer in men, often discovered after serum PSA testing [1]. Morphologically, most of the cancers are referred to as acinar, microacinar, or conventional adenocarcinomas. Carcinomas with architectural or cytological variations, e.g. atrophic, pseudohyperplastic, foamy gland, colloid and signet-ring, oncocytic and lymphoepithelioma-like, are descriptive terms used to help pathologists to recognize the diagnostic pitfalls. They have no known prognostic significance other than that of acinar adenocarcinoma, of which they are considered to be variants [2]. Unusual histological prostatic carcinomas, that account for 5–10% of the carcinomas that originate in the prostate, have been described, i.e. small cell (SCC), ductal adenocarcinoma (DA), sarcomatoid (SC, carcinosarcoma), basal cell (BCC), squamous cell (SqCC) and adenosquamous (ASC), and urothelial carcinoma (UC) [2]. Most of these variants are aggressive and with a poor prognosis. It is important for the urologist to be acquainted with their morphological features and their clinical significance, to manage patients appropriately. The aim of this review was to discuss the morphological features and the clinical significance of unusual histological variants of prostatic carcinoma. SCC SCC as a primary in the prostate [3–18] is a rare, extremely aggressive tumour that often presents with secondary deposits. Estimates of the incidence range from 0.3% [11] to 1% [16] of all prostatic carcinomas. In about half of cases it is pure SCC, while in the other half there is a mixture with prostatic acinar adenocarcinoma. In a third of patients there is an initial diagnosis of adenocarcinoma, followed by therapy, usually hormonal, in turn followed by a subsequent diagnosis of SCC [4,9,16]. CLINICAL FEATURES Most patients are aged 65–72 years (range 24–89). The most frequent presenting symptoms are related to BOO and disseminated disease [3]. In a few cases paraneoplastic syndromes have been reported. These include Cushing’s syndrome due to tumoral adrenocorticotropic hormone production, hypercalcaemia, hyperparathyroidism, thyrotoxicosis, and hyperglucagonaemia [3]. The presence of a paraneoplastic syndrome in a patient with prostatic carcinoma should prompt a histological search for a small-cell component. Between a third and two-thirds of patients with SCC present with an elevated serum PSA level. The DRE is often suspicious for malignancy, with an enlarged, irregular and stony-hard prostate. MORPHOLOGY Macroscopically, there is usually extensive involvement of the gland. The cut surface is grey-whitish and nodular. Extraprostatic extension into the seminal vesicles, periprostatic soft tissue and bladder can be easily visualized. Microscopically, SCC is identical to its more common counterpart in the lung. The tumour grows as sheets, with ribbons, nesting and pallisading along fibrous bands (Fig. 1A). An ‘Indian file’ pattern and rosette-like structures are occasionally noted. The polygonal, round or spindled tumour cells have scanty cytoplasm, with hyperchromatic nuclei, ‘salt and pepper’ stippled chromatin and inconspicuous nucleoli. Nuclear moulding can be evident. Both individual cell necrosis, manifested by karryorhectic debris, and large BJUI BJU INTERNATIONAL