Prostate cancer accounts for 9.7% of malignant tumours in men and is the most common cancer among males in the Western world.³ It is one of the leading causes of cancer death in men, second only to lung cancer, and an increasing number of men are being diagnosed with prostate cancer worldwide. Autopsy studies have shown invasive carcinoma in 8% of men in their 20s, rising to 80% for men in their 70s.⁴ It has been estimated that four-fifths of these cancers are truly occult but that one-fifth have the potential to become clinically manifest and eventually lethal. This malignancy is, however, not invariably lethal and may have a prolonged natural history, being now diagnosed at earlier stages due to widespread serum prostate-specific antigen (PSA) testing.

Thus, a large proportion of clinically significant cancers remain undetected. At the time of diagnosis, almost half of the cancers are advanced and a little over half are localised and potentially curable. These data emphasise the need for improvement in the diagnosis and detection of prostatic cancer. Some improvement may already have occurred. Rietbergen et al. found that among cancers detected by screening, 78% had organ-confined disease.⁵

The aetiology and pathogenesis of prostatic cancer are not known. The majority of prostate cancers are sporadic, and only 5–15% of cases are hereditary.⁶

Clinical symptoms develop only late in the disease. They are mainly related to bladder outlet obstruction. Such symptoms are non-specific and may be caused by prostatic enlargement of whatever nature, including benign prostatic hyperplasia and some forms of prostatitis. Haematuria or haemospermia are sometimes the first symptoms. However, most cancers are asymptomatic and detected by routine rectal palpation, abnormal transrectal ultrasound examination or by a raised serum PSA. Not infrequently, secondary deposits cause the presenting symptoms, for example, supraclavicular lymph node enlargement or pain from bone secondaries, while the primary tumour is silent.

FNA is guided by transrectal palpation. The Franzén guide cannula was designed to make it possible to position the needle accurately in the abnormal area felt with the fingertip. It is secured by a metal ring fixed to the fingertip and a plate in the palm of the hand. A rubber fingerstall is pulled over it. The needles are 23 gauge or 25 gauge and the results are comparable with CNB of the prostate.^8,15,16 Up to six passes can be made in one session but two to four are usually sufficient.

FNA of the prostate is an out-patient procedure that needs no patient preparation. Prophylactic administration of antibiotics should be considered in patients at increased risk of infection since septic reactions can occur. Post biopsy haematuria is a not infrequent occurrence but significant haemorrhagic complications do not occur even in patients on anticoagulant treatment.¹⁷

Whether to use air-dried smears stained with a Romanowsky stain, such as May–Grünwald–Giemsa (MGG) or Diff-Quik, or wet-fixed smears for Papanicolaou (PAP) or haematoxylin and eosin (H&E) staining, is a matter of personal preference. Air-dried smears are more dependent on correct smearing technique. Highly cellular smears from a cancer make good air-dried preparations. The thin liquid aspirate often obtained from benign prostatic hyperplasia is more suitable for a liquid-based technique or alcohol fixation.

Special stains are rarely used in prostatic cytology. Staining for PSA and for prostate-specific acid phosphatase (PSAP) is helpful in confirming a primary prostatic adenocarcinoma and in the distinction between adenocarcinoma and transitional cell carcinoma. Staining for high-molecular-weight cytokeratins, which are present in the prostate only in basal cells, has been found helpful in differentiating benign proliferative processes from well-differentiated adenocarcinoma.^18,19 A recent study has shown that detection of p504S is a sensitive and specific marker for prostatic carcinoma.²⁰ Immunohistochemical analysis is essential in the recognition of small cell carcinoma of neuroendocrine type. Finally, macrophage markers and PSA/PSAP can be used in distinguishing granulomatous prostatitis from poorly differentiated carcinoma, which is occasionally also a problem histologically.

It is usually not difficult to obtain cellular material from a case of benign prostatic hyperplasia (BPH). However, the cells may be diluted by a large amount of thin secretion and may need to be concentrated by two-step smearing. Admixture with blood is rarely a problem. In general, smears of BPH aspirates contain many fewer cells than smears from adenocarcinoma.

Cytological findings: benign prostatic hyperplasia

• Monolayered sheets of bland glandular epithelial cells

• Abundant pale cytoplasm, sometimes with red (MGG) cytoplasmic granules

• Distinct cell membranes producing a honeycomb pattern

• Uniformly distributed round or oval nuclei

• Bland granular chromatin, inconspicuous nucleoli

• Background of abundant thin and thick secretion

• Inflammatory cells variable.

Benign glandular epithelial cells are cohesive without overlapping or crowding and occur mainly as large monolayered sheets, reflecting the relatively large size of the glands in BPH. The cells are polygonal with central round nuclei and abundant pale cytoplasm, and cell membranes are distinctly visible, giving the epithelial sheets a honeycomb pattern. Single cells are uncommon unless too much pressure at smearing has caused the sheets to break up. However, it has been pointed out that small groups of cells suggestive of loss of cohesion occur in prostatic smears from men younger than 40 years.²²

The nuclei of benign epithelial cells have inconspicuous nucleoli and finely granular chromatin (Fig. 19.1). In MGG-stained smears, coarse dark red cytoplasmic granules are commonly present (Fig. 19.1A). The granules are a strong indicator of benignity, although they can occasionally be found also in well-differentiated carcinoma.

Fig. 19.1 Benign prostatic glandular epithelium. Monolayered sheets with regular distribution of nuclei, visible cell membranes and coarse red cytoplasmic granules visible in (A) (A: MGG; B: PAP).

Smears may have a thin and watery background of secretion, with a high protein content condensed to dark staining clumps, amyloid bodies or concretions. A small number of histiocytes, lymphocytes and neutrophils are frequently seen in the absence of prostatitis. Fragments of spindle smooth muscle cells and stroma are rarely seen (Fig. 19.2).

Fig. 19.2 Fragment of smooth muscle stroma in smear from case of BPH (MGG).

Other elements that may be found in BPH are metaplastic or mature squamous epithelial cells from the mucosa of the bladder neck or urethra, and mucin-secreting columnar cells from the rectal mucosa, and cells from the seminal vesicles. The metaplastic cells are cytologically bland and should not raise a suspicion of malignancy.