Requerimientos funcionales por macroproceso

TESTICULAR MALDESCENT 1. Epidemiology of testicular tumor formation

Although many risk factors have been proposed for the etiology of testicular can- cer in human, only a history of UT is a well established one (UK Testicular Cancer

Study Group, 1994a; UK Testicular Cancer Study Group, 1994b). UT is associated with

testicular neoplasia not only in humans but also in other mammalian species such as horses and dogs (Boothe, 1993; Johnston

et al., 2001; Wintzer, 1986). The magnitute

of the relative risk is a point of considerable disagreement var ying among several reports between 5-50 times greater and 9.2-13.6 times greater in humans and dogs, respectively, compared to the general popu-

lation (Cortes et al., 2001; Farrer, 1985;

Johnston et al., 2001; UK Testicular Cancer Study Group, 1994b; Whitaker, 1988; Woodhouse, 1991). No increase in risk

seems to exist in cases of men with a histo- ry of spontaneous TD (Moller et al., 1996). The relative frequency of a history of UT in men with testicular tumors (TT) is 15-fold for unilateral and 33-fold for bilateral UT

(Stone et al., 1991), respectively. Location

of the UT also affects the relative risk of developing a TT; the higher the position the testis, the greater the risk of developing a malignancy (Martin, 1982; Martin & Menck,

1975). Inta-abdominal testes have a greater

risk of malignancy, compared with testes palpable in the groin (Stone et al., 1991)

(Campbell, 1942). The most common TT

that develops from an UT is seminoma in human (Abratt et al., 1992; Batata et al.,

1980; Martin, 1979; Martin, 1982; Stone et al., 1991), while the incidence of seminoma

and Sertoli cell tumors is almost equal in dogs with TMD (Johnston et al., 2001). Other rarer histological types encountered in men with a histor y of TMD include embryonal carcinoma, teratocarcinoma, and choriocarcinoma (Batata et al., 1980). TT develop usually during or after puberty although there are sporadic case reports of development before 10 years of age (for review see Doi et al., 2002). In childhood, seminoma is not as common compared to adulthood (Miller et al., 1999). Although rare in the general population, the most common TT associated usually with intra- abdominal UT in childhood is mature ter- atoma (Doi et al., 2002).

2. Pathogenesis of testicular tumor formation

The cause of the increased risk for malignant testicular degeneration of the UT is unclear. It has been speculated that TT may arise due to an intrinsic testicular

abnormality responsible also for the initial TMD, rather than due to secondary dyspla- sia caused by abnor mal temperature

(Giwercman et al., 1988). Although a sec-

ondary effect cannot be ruled out, the theo- ry of an intrinsic pathologic process affect- ing both testes seems more plausible. It is supported by the evidence of a ~3.5-fold increased risk of the CDT in cases of unilat- eral UT (~15-20% of all TT occur in the CDT) (Batata et al., 1980; Hutson &

Beasley, 1992; Johnson et al., 1968; Martin, 1982; Prener et al., 1996). Furthermore,

among men with bilateral UT and unilateral TT, 15% of the contralateral to the primary tumor testes develop malignancy (Schneck

& Bellinger, 2002).

In adults, carcinoma in-situ (CIS) germ cells are currently considered the precur- sors for all germ cell tumors, except sper- matocytic seminoma (Skakkebaek et al.,

1987). These cells are presumed to be

malignant gonocytes derived from primor- dial germ cells that escaped normal differ- entiation in utero.501 The incidence of CIS is estimated ~1.7% in adults with a history of TMD (Giwercman et al., 1989). CIS is more commonly detected in intra-abdomi- nal testes (Ford et al., 1985). Germ cell tumors have been noted to develop in 40- 50% of adults during a 5-year period from the diagnosis of CIS (von der Maase et al.,

1986). The interval between the diagnosis

of CIS and the development of seminoma in an UT may last more than 10 years, while spontaneous regression of CIS has not been recorded (Sigg & Hedinger,

1983). On the other hand, CIS seems to

be an extremely rare finding before adult- hood (Cor tes et al., 2001). In a large series of testicular biopsies taken at sur- gery (before adulthood) from 1335 patients with UT, CIS was detected only in 6 patients (2 with intra-abdominal testes, 3 with abnormal external genitalia besides

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TMD and 1 with abnor mal kar yotype [45,X/46,XY]). Based on these results, the authors recommended examination for tes- ticular neoplasia by testicular biopsy at orchidopexy only in cases accompanied by these characteristics. However, the biolog- ic behaviour of CIS in the prepuber tal testis has not yet been clarified. The pre- dictive value of the identification of placen- tal-like alkaline phosphatase positive germ cells (a reliable immunohistochemical marker for confirmation of the CIS histo- logical diagnosis) (Giwercman et al., 1991) in prepubertal testicular biopsy speciments for future malignancy has been questioned

(Engeler et al., 2000). Therefore, the value

of routine testicular biopsy at orchidopexy during childhood as a possible aid in the identification of patients at risk for future testicular neoplasia is questionable. It is controversial whether orchiopexy affects the natural history of development of TT, although there is emerging evidence to support that prepubertal orchiopexy may lessen the risk (Moller et al., 1996; Prener

et al., 1996; Raina et al., 1995; UK Testicular Cancer Study Group, 1994b). It

should be emphasized that orchiopexy will allow a more thorough examination of the testis for earlier detection of futural malig- nant degeneration.

6. MANAGEMENT OF TESTICULAR MALDESCENT: HORMONAL TREATMENT & SURGERY

Early management of boys referred for an empty scrotum is mandatory in order to maintain testicular function. Objective of any therapeutic intervention is the position- ing of the gonad in the scrotum before 1 year of age. Spontaneous descent occurs in the majority of cryptorchid children by 3 months of age and it is very rare thereafter. Consideration for earlier intervention should be made to prevent complications of UT

that may be manifested before the first year of life.