Yolk sac tumor

* Splenogonadal fusion is a rare congenital malformation in which the spleen is abnormally connected to the gonads or to the mesonephric derivatives. A few more than 150 cases have been described in the world literature. We report an additional case of splenogonadal fusion. A nonseminomatous germ cell tumor was found in the testicle involved in this splenogonadal fusion. To our knowledge, this is the third reported case of a testicular neoplasm associated with splenogonadal fusion and the first reported case of intra-abdominal nonseminomatous germ cell testicular tumor arising in this rare anomaly. The literature pertaining to splenogonadal fusion and the testicular tumor arising in this anomaly is briefly reviewed.

(Arch Pathol Lab Med. 2002;126:1222-1225)

Splenogonadal fusion is a rare congenital malformation that results from abnormal connection of splenic tissue with gonadal-mesonephric structures. The first detailed description of this condition was offered in 1889 by Pommer, as cited by Putschar and Manion1 in their classic review of this anomaly. The same authors classified this anomaly into 2 types, namely, continuous and discontinuous. In the continuous variant, the spleen is connected to the gonads by either a fibrous cord, a splenic cord, or a beaded cord of mixed fibrous and splenic tissue. In the discontinuous variant, the ectopic tissue is attached to the gonad, but no connection with the orthotopic spleen is identified. The sex distribution strongly favors males. It can occur as an isolated condition or can be associated with other abnormalities, such as cryptorchidism, peromelia, and micrognathia. We describe an additional case of a continuous-type splenogonadal fusion associated with an intra-abdominal nonseminomatous germ cell testicular tumor in a man with bilateral cryptorchidism.

REPORT OF A CASE

A 27-year-old white man with bilateral cryptorchidism was seen in the emergency room because of constant sharp pain in the left flank radiating to the left groin. The condition started approximately 4 weeks prior to admission as a dull constant pain in the left flank, which was partially relieved by a muscle relaxant. The physical examination findings included tenderness of the left mid and lower quadrant of the abdomen. Clinically, a visceral infarction was suspected and computed tomographic scan of the abdomen showed a mass in the left paracolic gutter with a moderate amount of ascites. The laboratory results included an elevated serum lactate dehydrogenase level of 593 U/L (reference range, 56-197 U/L), markedly increased serum beta-human chorionic gonadotropin (beta-hCG) at 24552 mIU/mL (reference range,

MATERIALS AND METHODS

The surgical specimens were fixed in 10% neutral buffered formalin. Standard paraffin-embedded sections were stained with hematoxylin-eosin. Immunoperoxidase stains were performed with a Ventana Immunostainer (Ventana Medical Systems Inc, Tucson, Ariz). A biotin-avidin technique was used, in which diaminobenzidine was used as a chromogen with a panel of antibodies against the following antigens: alpha-fetoprotein (Dako Corporation, Carpinteria, Calif), beta-hCG (Dako), pan-keratin (AE1/AE3; Ventana), Ber-H2 (CD30; Dako), and placenta-like alkaline phosphatase (Ventana). No antigen-retrieval techniques were used for any of the antibodies.

Sections with known reactivity for the antibodies assayed served as positive controls, and the sections treated with normal mouse serum (1:200) served as negative controls.

PATHOLOGIC FINDINGS

On macroscopic examination, an 8.2 X 3.5 X 2.5-cm, gray-tan, irregular, solid tumor mass attached to a 9.0 X 2.0-cm, purplish-red, cordlike structure was noted. The cut surface of the tumor was tan to brown with friable yellow areas of necrosis. The cordlike structure showed normal splenic tissue. Also submitted was a 98-g and 9.0 x 6.0 x 3.5-cm spleen that was grossly unremarkable except for the hilar surgical defect from previous excision of the cordlike structure (Figure 1).

Histologic examination of the tumor revealed a malignant neoplasm consisting of pleomorphic epithelial cells with prominent nucleoli forming trabecular, papillary, glandular, and solid patterns. A few foci of intratubular germ cell neoplasia were also noted. No vascular-lymphatic invasion was seen (Figure 2). Necrosis and numerous mitoses were present. In many areas, the pleomorphic epithelial cells with prominent nucleoli formed a microcystic pattern, and scattered syncytiotrophoblastic cells were also identified (Figure 3). The tumor almost completely replaced the testicular tissue and infiltrated the surrounding connective tissue capsule. The capsule and pulp of the adjacent fused, splenic, cordlike structure showed tumor infiltration as well (Figure 4). A small amount of residual uninvolved atrophic testicular tissue and epididymis was also identified.

Immunohistochemical stains showed strong reactivity for AE1/AE3 in the trabecular/glandular/solid components and syncytiotrophoblasts (Figure 5), alpha-fetoprotein and AE1/AE3 positivity in the tumor islands with microcystic pattern, and Ber-H2 (CD30) positivity in the trabecular/glandular/solid components (Figure 6). Staining for placenta-like alkaline phosphatase was positive in the trabecular/glandular/solid components. Periodic acidSchiff-positive (diastase-resistant) globules were noted in the microcystic areas. Sections of the orthotopic spleen were unremarkable.

The morphologic and immunohistochemical features were diagnostic of nonseminomatous germ cell testicular tumor composed of embryonal carcinoma and yolk sac tumor. Embryonal carcinoma formed about 65% of the tumor and yolk sac tumor constituted the rest of the tumor. The pathologic stage of disease was pT4 pNX pMX.

COMMENT

Splenogonadal fusion is a rare congenital anomaly in which there is an abnormal connection of the spleen to the gonads or rarely to the mesonephric derivatives, such as ductus epididymis and vas deferens. Approximately 150 cases of this anomaly have been published in English literature.1-3 Splenogonadal fusion can be of 2 types, namely, continuous and discontinuous. In the continuous type, the spleen is connected to the gonadal-mesonephric tissue by a continuous cordlike structure of fibrous or splenic tissue. The discontinuous type shows no structural connection between the ectopic spleen at the gonadal-mesonephric tissues and the regular spleen.1 The 2 forms appear to occur with relatively equal frequency, and about one fifth of the continuous-type cases are associated with other major congenital abnormalities, such as limb defects, micrognathia, cardiac defects, palatal defects, and anal defects.3 The majority of the cases are diagnosed in patients younger than 20 years of age. The male-female ratio is reported to be about 15:1.(3)

It has been assumed that this anomaly occurs sometime between the fifth and eighth weeks of gestation, before the beginning of gonadal descent and at the time when the splenic anlage lies in close proximity to the left gonad during rotation of the dorsal mesogastrium.2 Although the exact cause of this malformation is not known, the most popular theory is of simple adhesion 2 between the peritoneal surface of the spleen and the gonadal ridge, causing splenogonadal fusion. Von Hochstetter4 proposed the second theory of migrating splenic cells, in which the splenic anlage cells could come in contact with the gonadal anlage through the retroperitoneum by a caudal-limiting fold that serves as a bridge over the coelomic cavity. Cortes et al5 proposed that the abnormal development of the diaphragmatic ligaments of the testis lead to lack of their involution with consequent cryptorchidism and colonization of the abnormal ligaments by splenic cells.

The pathogenesis of the presence of other congenital defects at a relatively higher frequency among patients with splenogonadal fusion is even more complex. As the limb buds, mandible, and splenic bud in the dorsal mesogastrium develop at approximately the same time, injury at this critical stage of development would explain the associated anomalies.6

Splenogonadal fusion typically presents as left scrotal swelling, left inguinal hernia, or cryptorchidism.3 Other presentations include painful scrotal swelling secondary to malaria or mumps, traumatic rupture of ectopic spleen, and bowel obstruction caused by cordlike structure in continuous form.7 The diagnosis is usually made during surgery or at autopsy. Due to the rarity of this condition, the preoperative diagnosis has been made very rarely.8 Occasionally, radiographic procedures have been used to make the preoperative diagnosis.7

To our knowledge, only 2 cases of malignant testicular tumor arising in splenogonadal fusion (Table) have been reported previously in the literature.9,10 One case presented as bilateral cryptorchidism with suspicion of an intraabdominal testicular neoplasm and had abnormally elevated beta-hCG levels.9 Histologically, the testicular neoplasm was diagnosed as anaplastic seminoma. The other case presented with left testicular tumor and had a past history of left cryptorchidism and left orchiopexy. The serum (alpha-fetoprotein level was elevated. Histologic diagnosis was combined malignant testicular tumor. Our case presented as bilateral cryptorchidism and was highly suspicious for a malignant intra-abdominal testicular neoplasm based on the computed tomographic scan findings and marked elevation of both beta-hCG and alpha-fetoprotein. Splenogonadal fusion, however, was diagnosed only intraoperatively.

To the best of our knowledge, this is the third reported case of a testicular neoplasm associated with splenogonadal fusion and the first reported case of an intra-abdominal nonseminomatous germ cell testicular tumor arising in splenogonadal fusion. Moreover, we believe our case of nonseminomatous germ cell tumor arising in this rare setting is the first reported case in which the existence of 2 germ cell components is supported by extensive immunohistochemical analysis.

The authors thank Michael T. Mazur, MD, Crouse Hospital, Syracuse, NY, for reviewing this case and confirming our diagnosis. The authors also thank Trade Bird for her excellent secretarial assistance.

References

1. Putschar WGJ, Manion WC. Splenic-gonadal fusion. Am JI Pathol. 1956;32: 15-33.

2. Gouw ASH, Elema JD, Bink-Boelkens MTE, de Jongh HJ, ten Kate LP. The spectrum of splenogonadal fusion: case report and review of 84 reported cases. Eur J Pediatr. 1985;144:316-323.

3. Carragher AM. One hundred years of splenogonadal fusion. Urology. 1990; 35:471-475.

4. von Hochstetter A. Milzgewebe im linken Ovarium des linken Individualteiles eines menschlichen Thoracophagus. Virchows Arch A. 1953;324:36-54.

5. Cortes D, Thorup JM, Visfeldt J. The pathogenesis of cryptorchidism and splenogonadal fusion: a new hypothesis. Br J Urol. 1996;77:285-290.

6. Loomis KF, Moore GW, Hutchins GM. Unusual cardiac malformations in splenogonadal fusion-peromelia: relationship to normal development. Teratology. 1982;25:1-9.

7. Nimkin K, Kleinman PK, Chappell JS. Abdominal ultrasonography of splen-- ogonadal fusion. J Ultrasound Med. 2000;19:345-347.

8. Kadlic T. Nebenmilz in einer angerborenen Skrotalhernie. Zentralbl AlIg Pathol. 1943;81:49-52.

9. Falkowski WS, Carter MF. Splenogonadal fusion associated with an anaplastic seminoma. J Urol. 1980;124:562-564.

10. Thomsen BM, Wierod FS, Rasmussen KC. Combined malignant testicular tumor and splenogonadal fusion. Scand] Urol Nephrol. 1997;31:393-395.

Sandy L. Imperial, MD; Jagmohan S. Sidhu, MD

Accepted for publication December 6, 2001.

From the Department of Pathology and Laboratory Medicine, United Health Services Hospitals, Johnson City, NY.

Reprints: Jagmohan S. Sidhu, MD, Department of Pathology and Laboratory Medicine, United Health Services Hospitals, 33-57 Harrison St, Johnson City, NY 13790 (e-mail: Jagmohan-sidhu@uhs.org).

Copyright College of American Pathologists Oct 2002
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