Anatomical and Histological Classifications

The urethra can be subdivided into an anterior and a posterior component. The posterior urethra comprises the prostatic and membranous parts and the urethral epithelial lining is of transitional cell origin. The anterior urethra consists of the bulbar and

Department of Urology, Royal Surrey County Hospital, Guildford, Surrey, UK

A. Muneer et al. (eds.), Textbook of Penile Cancer,

DOI 10.1007/978-l-84882-879-7_8, © Springer-Verlag London Limited 2012

Fig. 8.1 Anatomical subdivision of the male urethra

Fig. 8.1 Anatomical subdivision of the male urethra

Table 8.1 The distribution of the tumor subtypes is dependent on the urethral segment that they arise from

Urethral location

Epithelium

Tumor subtype

Prostatic

Bulbo- membranous Penile

Urothelium

Pseudostratified columnar cells

Stratified squamous

Adenocarcinoma, SCC, TCC SCC

Table 8.2 Reported frequency of histological subtypes

Literature reports Epidemiological data n 212 1615

Adenocarcinoma (%) 8 16

penile urethra and there is a transition from pseudostratified columnar to stratified squamous epithelium in the anterior urethra (Fig. 8.1). The three main tumor subtypes which occur in the male urethra are transitional cell carcinomas (TCC), squamous cell carcinomas (SCC), and adenocarcinomas. Melanoma and lymphomas have also been reported but are rare.

Squamous cell carcinomas are the commonest histological subtype followed by transitional cell carcinomas and then adenocarcinomas. Anterior urethral tumors are also more common than posterior urethral tumors. In the fossa navic-ularis and the anterior urethra SCC predominates. However, in the posterior urethra TCC accounts for approximately 90% of the tumors. In the bulbar and membranous regions, adenocarcinomas or SCC account for 80-90% of the tumors. (Table 8.1).3

A comparison of the relative frequency of urethral tumors from literature reports 4-12 and epidemiological data2 reflects the inaccuracy of the true incidence of this tumor (Table 8.2).

Table 8.3 TNM staging for male urethral cancer

Primary tumor (T)

Tis T1 T2

Regional lymph nodes (N)

Distant metastasis (M)

Primary tumor cannot be assessed No evidence of primary tumor Noninvasive papillary, polypoid, or verrucous carcinoma Carcinoma in situ

Tumor invades subepithelial connective tissue Tumor invades any of the following: corpus spongiosum, periurethral muscle, prostate Tumor invades any of the following: corpus caverno-

sum, beyond prostatic capsule, bladder neck Tumor invades other adjacent organs

Regional lymph nodes cannot be assessed No regional lymph nodes Metastasis in single lymph node (<2 cm) Metastasis in single lymph node (>2 cm) or multiple nodes

No distant metastasis Distant metastasis

Adapted from Edge13

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