Urol Radiol 11:113-117 (1989)
Urologic Radiology © Springer-VedagNewYorkInc.1989
CT and MR Imaging of Malignant Germ Cell Tumor of the Undescended Testis James G. Lorigan, I Ali Shirkhoda, ~ and Francisco H. Dexeus 2 Departments of lDiagnostic Radiology, Division of Diagnostic Imaging, and 2Medical Oncology,
The University of Texas M. D. Anderson Cancer Center at Houston, Houston, Texas, USA
Abstract. Preoperative localization of the impalpable undescended testis is necessary to facilitate proper surgical planning. There is an increased incidence of malignant change in the undescended testis; demonstration of malignancy before surgery will significantly alter the treatment. We describe the computed tomographic (CT) and magnetic resonance (MR) findings in 2 patients with malignant change in an intraabdominal testis. The CT scan revealed lesions with areas of low density, 1 of which had focal calcifications; MR revealed lesions of predominantly low or intermediate signal intensity on both long and short TR/TE images, with some areas of very high signal on both sequences. After initial management with chemotherapy, the residual tumor was surgically resected. In neither instance was residual normal testis demonstrated. Both CT and M R are ideal methods of examining malignant transformation of the undescended testis, because of their ability to characterize the internal structure of the organ and, in the case of MR, its capacity for multiplanar imaging. They are almost of equal value except for the ability of CT to identify calcification and of M R to diagnose hemorrhage.
Case Reports
Key words: Testis, germ cell tumor -- Computed tomography, testis -- Magnetic resonance, testis.
Case 1
Address reprint requests to: A. Shirkhoda, M.D., William Beaumont Hospital, Department of Diagnostic Radiology, 3601 West 13 Mile Road, Royal Oak, MI 48072, USA
A 29-year-old man presented with a 6 month history of right lower abdominal pain. The right testis was impalpable. Excretory urography and barium enema showed a pelvic mass compressing the bladder and the bowel. This was further confirmed by CT scan, which demonstrated a large noncalcified inhomogeneous tumor (Fig. 1A) compressing the rectum and bladder without local invasion. Serum alpha-fetoprotein (AFP), beta human chorionic gonadotropin (BHCG), and lactate dehydrogenase (LDH)
Undescended testis is present in approximately 0.3% of adult men [l]. Twenty percent of these testes lie within the abdomen or pelvis [1]. The undescended testis has an increased risk of torsion and malignant change [1, 2] and may be atrophic, sometimes resulting in infertility [2, 3]. In the adult, unilateral undescended testis is treated by surgical removal [3, 4]. When there is bilateral maldescent in an adult and biopsy excludes malignancy, orchiopexy is performed to preserve endocrine function and to facilitate clinical observation and follow-up [3, 4]. Computed tomography (CT) has been considered the modality of choice for localizing the impalpable undescended testis [5, 6]. Arteriography [7], venography [8], and sonography [9, 10] have also been used, with varying rates of success, complications and limitations. The role of magnetic resonance (MR) imaging in the assessment of scrotal [11-14] and undescended [15] testes is now being defined. We discuss here the use of CT and M R in the evaluation of 2 patients with malignant germ cell tumor in an intraabdominal testis.
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Fig. 1. Case 1. Nonseminomatous germ cell tumor of an undescended right testis. A Pelvic CT scan shows a 9 x 8 cm, well-defined mass with areas of low density in the midpelvis. No calcification was seen. B Coronal short TR/TE pulse sequence (TR = 800, TE = 25) shows a well-defined mass of intermediate signal intensity with some focal areas of higher signal intensity. There is extrinsic compression of the bladder. The height of the tumor is approximately 10 cm. C Axial MR image using long TR/TE pulse sequence (TR = 2000, TE = 80) through the midpelvis shows a mass of nonhomogeneous signal intensity displaying several areas of very bright signal. These areas could be due to fat or a combination of hemorrhage and neoplastic processes; however, the resected specimen contained mature teratoma without significant fat or hemorrhagic components.
levels were all elevated. The MR was performed on a 1.5 Tesla superconducting magnet (General Electric, Milwaukee). Most of the mass was of intermediate signal intensity on short TR/TE (TR = 800, TE = 25) and bright on long TR/TE (TR = 2000, TE = 80) images. There were scattered areas of high signal intensity (Fig. 1B, C) on both pulse sequences, consistent with fat or hemorrhage. Due to the elevated levels of serum biomarkers and this mass, a presumptive diagnosis of malignant germ cell tumor in an undescended testis was made and the patient received 4 courses of systemic combination chemotherapy. Four months after the initial referral, his biomarker levels were close to normal. At surgery, a well-encapsulated, 8 cm mass covered with peritoneum was seen to arise from a stalk of the vas deferens. There was no evidence of residual normal testis. The mass and adjacent lymph nodes were excised. Histologic analysis showed a mature teratoma with areas of necrosis. There were no significant fatty or hemorrhagic areas. Mature teratoma was found in 1 of 6 interaorticocaval nodes. The patient received 2 more courses of chemotherapy because of marginal elevation of AFP (7.4 ng/ml; normal, 0-5 ng/ml) and BHCG (3-6 mlU/ml; normal, 0 3 mlU/ml) levels at the time of surgery. Six months later, he was
in complete remission and indications of biomarkers were negative.
Case 2 A 22-year-old man presented at another hospital with sudden onset of right lower quadrant pain and fever. A provisional diagnosis of acute appendicitis was made. The patient was found to have a palpable midline lower abdominal mass, and the right testis was not palpable. Ultrasound-guided fine needle aspiration biopsy of the mass showed seminoma with extensive necrosis. The patient was referred to M. D. Anderson Hospital for further evaluation and treatment. The CT scan showed a large lower abdominal mass with some peripheral calcification (Fig. 2A) and central areas of low attenuation consistent with necrosis. An MR study was performed on a 1.5 Tesla superconducting unit. On both short (TR = 1000, TE = 20) and long (TR = 2000, TE = 80) TR/TE images, the mass was predominantly of low and intermediate signal intensity. The area of low signal on the long TR/TE image corresponded to the calcification shown on CT.
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Fig. 2. Case 2. Mixed germ cell tumor of an intraabdominal right testis. A Unenhanced CT scan of the pelvis demonstrates a large, low-density mass with areas of calcification. B Midline sagittal MR image using short TR/TE pulse sequence (TR = 1000, TE = 20) shows a 15 x 8 cm, relatively homogeneous mass with areas of low and intermediate signal intensity. There are areas of higher signal intensity inferiorly. C Axial M R scan in long TR/TE pulse sequence (TR = 2000, TE = 80) shows a 12 cm, well-defined mass with focal areas of high signal intensity and an area of very low signal intensity due to calcification. D Cut section through the surgical specimen shows solid glistening areas of viable seminoma and embryonal carcinoma (arrows) surrounded by areas of fibrosis, necrosis, and focal hemorrhage. No significant fatty component was found. The mass is within a pseudocapsule (arrowheads).
There were also focal areas of increased signal intensity on both sequences (Fig. 2B, C) probably due to fat or hemorrhage. There was marked elevation of serum AFP, BHCG, and LDH levels, on which basis it was decided to treat the tumor as a mixed germ cell tumor rather than as a pure seminoma. The patient received 4 courses of systemic combination chemotherapy; his biomarker levels normalized after the first course. However, due to the persistence of the pelvic mass, surgery was performed. At operation, a mass with areas of viable seminoma and embryonal carcinoma intermixed with areas of necrosis, fibrosis, and focal hemorrhage was found attached to
epididymis (Fig. 2D). There was no significant fat component. No evidence of the residual normal testis was found. This patient died unexpectedly 2 months after surgery. This may have been due to a cardiac arrhythmia: autopsy showed widespread metastases, with involvement of the myocardium.
Discussion Although undescended testis occurs in only 0.3% of adult males, approximately 10% of testicular neo-
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plasms arise in undescended testes [1, 2]. Malignancy in the undescended testis is up to 48 times more common than in the normally sited testis [ 1]. The malignancy rate correlates with increasing distance of the testis from the scrotum [3]; thus, malignant change is 6 times more common in the abdominal than in the inguinal testis [1]. Torsion is not uncommon and as many as 64% of patients with torsion of an intraabdominal testis have associated testicular cancer [16]. Torsion implies a good prognosis since it means that the tumor is confined within the tunica albuginea without direct local spread. The spectrum of pathologic changes in intraabdominal testicular tumors is similar to that ofintrascrotal neoplasms. If the testis is impalpable, it should be localized preoperatively to facilitate surgical planning and to rule out the occasional case oftesticular agenesis. This requirement is emphasized by the experience of Brothers et al. [ 17], who found that 5 of 13 patients with malignancy in an intraabdominal testis had undergone previous exploratory surgery that failed to locate the undescended testis. Testicular arteriography and venography both require considerable expertise and have significant morbidity and technical failure rates even in the best hands [4, 7, 8]. Ultrasound can be very useful in localizing testes that lie close to the inguinal ligament but frequently does not demonstrate the intraabdominal testis [9, 10]. To date, CT has been the imaging modality of choice for preoperative localization of the intraabdominal testis. It may also give information about neoplastic involvement of the testis [ 18], the presence of calcification, as in our case, and also the presence or absence of retroperitoneal adenopathy. The major pitfall is differentiating a loop of unopacified bowel from an undescended testis. On MR, the normal descended testis characteristically has a homogeneous signal of intermediate intensity on short TR/TE images and of high intensity on long TR/TE images [ 11, 13, 14]. The tunica albuginea is normally seen as a thin band of low signal intensity surrounding the testis. Here also it may become difficult to differentiate an undescended testis from a loop of bowel, which is likely to persist at least until effective gastrointestinal contrast media become available for general use in M R imaging. Testicular tumors usually have a nonhomogeneous signal that is lower, particularly on long TR/TE images, than that of the normal testis [12, 13]. Nonseminomatous germ cell tumors may contain areas of high signal intensity, probably representing hemorrhage. In our patients, focal areas of high signal were also identified. These most likely
J.G. Lorigan et al.: CT and MR of Testis Tumors
represented hemorrhage, since there was no evidence of significant fat either on CT or in the resected specimen. Recent work suggests that M R spectroscopy may be valuable in assessing testicular metabolic activity [19]. In the undescended testis, M R can demonstrate atrophy [15] and, as in our patients, malignant change; its ability to evaluate the metabolic integrity of the undescended testis has not yet been determined. MR's advantages over CT include its capacity for multiplanar imaging and superior tissue characterization. However, CT scanning is more widely available and also has the advantage of being able to demonstrate calcifications. Our experience with these patients suggests that both M R and CT are safe, noninvasive methods of preoperatively evaluating the site and internal architecture of the malignant undescended testis. These modalities are of particular value in the patient with an impalable testis. In our patients, there was no significant advantage of either, except for the ability of CT to evaluate calcifications and of M R to demonstrate better the internal architecture and probably hemorrhage. Acknowledgments. The authors thank Sharon Williams and Arlene Hill for manuscript preparation and Gene Szwarc and Robert Czimny for preparation of the illustrations.
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