Discontinuous-type splenogonadal fusion that thought to be a testicular neoplasm: A case report of a rare entity

Abstract

Ectopic Splenic tissue is often found in medical literature. It is usually found near the main spleen, however, there are also some atypical areas are involved like the scrotum which is called splenogonadal fusion. The diagnosis is usually made incidentally. Although splenogonadal fusion is usually seen in children, cases have also been reported in adults. Due to the lack of radiological features, the initial diagnosis is often difficult as It mimic some other pathologies, especially cancer. In this case we present a case with left testicular mass thought to be testicular malignancy but diagnosed through histopathology as splenogonadal fusion.

1. Introduction

Splenogonad fusion (Splenogonadal Fusion) is a rare benign congenital anomaly that occurs when there is an abnormal connection between the spleen (native spleen or ectopic splenic tissue) and the gonads or mesonephric remnants. The first report was made by the German pathologist Bostroem in 1883.1, 2, 3 Lubarsch found that ectopic splenic tissue is a common finding in the elderly and is frequently found on routine biopsies, with an incidence of 2 %–35 %.⁴ The spleen is usually located near the native spleen, usually at the hilum or in the surrounding ligaments. Atypical sites are involved such as the jejunal wall, mesentery, pelvis, and occasionally the scrotum.⁵ Splenogonadal fusion usually presents as a scrotal swelling or mass called cryptorchism; it occurs most often on the left side and is often misdiagnosed as a testicular or epididymal tumor.¹ It is difficult to diagnosis this condition due to its rarity causing a significant number of patients frequently undergo unnecessary orchidectomies. Ultrasonography (USG) is the initial diagnostic test for the evaluation of a scrotal mass. Color Doppler and ultrasound elastography provide important diagnostic criteria. Cross-sectional imaging techniques, including magnetic resonance imaging (MRI) and computed tomography (CT), can provide additional information to confirm the diagnosis.⁶ This report describes a case of scrotal swelling which the histopathologically confirmed to be associated with Splenogonadal fusion.

1.1. Case presentation

A 32-year-old male patient, presented with 6 year history of primary infertility. He has history of left testicular torsion treated by orchidopexy at the age of 6 months otherwise healthy, with no significant family or medical history. Physical examination revealed non tender, large and hard left testis with hard and thick left spermatic cord also small right testis. Ultrasound revealed enlargement of the left testis that was mostly replaced by lobulated hypoechoic mass with possible invasion to the left epididymis which was measured 9 × 8 × 5.5 cm. The mass showed hypervascularity with dilated tortuous surrounding vessels. The right testis appeared inhomogeneous, atrophied with positive doppler flow. MRI showed infiltrative lobulated mass occupying the left testis which appeared homogenous hypointense on T2WI and Isointense on T1WI with heterogenous enhancement and marked diffusion restriction (Figure-1-). The differential diagnosis was malignant tumor (non seminomatous gem cell tumor). Accordingly the patient underwent left radical orchiectomy, but histopathology after excision shows histologic features resembling normal splenic parenchymaand normal testicular tissue no signs of malignancy confirming the diagnosis of splenogonadal fusion This emphasizes the importance of excisional biopsy in cases with ambiguous imaging findings, as it is crucial for definitive diagnosis. (Fig. 2-).

Fig. 1.

Pelvic MRI with IV contrast showed lobulated mass with extension into left inguinal canal. A. Coronal and B axial T1 post contrast: The mass shows heterogenous enhancement. C. Axial ADC map and D. DWI images: The mass shows true diffusion restriction.

Fig. 2.

Splenogonadal fusion histopathology A. Low power view (2.5x): well defined nodule composed of white pulp and red pulp resembling normal spleen with fibrous capsule (left side), well demarcated from adjacent testicular tissue (right side). B. High power view (20X): shows histologic features resembling normal splenic parenchyma composed of lymphoid follicles (white pulp, single arrow), and thin walled venous sinusoids (red pulp, double arrows). C High power view (20X) of adjacent testicular tissue, some of the tubules show atrophic changes in form of peritubular fibrosis and absence of spermatogensis

2. Discussion

Splenogonadal fusion is a rare congenital malformation, first reported by Bostroem in 1883. This can be associated with other abnormalities such as cleft palate, heart defects and micrognathia,^1,7 however in our case there was no such association. In 1956, Putschar and Manion published a comprehensive review of 30 cases of splenogonadal fusion and established a classification system that divided splenogonadal fusion into two different types: continous and discontinuous. The previous literature showed that the continous form was reported slightly more frequently (58 %) than the discontinous form,1, 2, 3^,7,8 the presenting case showes the discontinuous type. Various theories have been proposed to explain the atypical combination of spleen and gonadal tissue.^7,9 During embryogenesis, the left gonad is located near the spleen, causing the Splenogonadal fusion to always appear on the left side (like our case).^1,3,5 During embryonic development, testicular descent may cause the spleen to elongate and fuse with the testis to form a long band (continuous splenogonadal fusion) or a segment of the splenic primordium may migrate along side of the testes (discontinuous splenogonadal fusion).⁶

Based on the review of literature published by Kumar et al. cryptorchidism was the most common symptom with 28 %, followed by scrotal swelling with 23.5 % (14.9 %), testicular mass (8.9 %), scrotal pain and swelling (3 %), incarcerated/strangulated inguinal hernia (3 %), hydrocele (3 %), scrotal pain/torsion (1.5 %) and others.¹⁰ In the presenting case the patient complained from painless scrotal swelling which considered as the most common symptom.

Ultrasonographic findings alone are insufficient for establishing a definitive diagnosis of splenogonadal fusion as there is no specific ultrasound features. . In B-mode splenogonadal fusion can be identified as well-defined, lobulated, encapsulated, homogeneous, hypoechoic mass near the testis¹¹. In color doppler ultrasound it shows increased vascularity which characterized by a branching or radiating vascular pattern like normal splenic tissue with normal testicular tumor markers for malignant tumors, the possibility of splenogonadal fusion should be considered (like our case). In contrast the tumor, Testicular tumors are typically irregular in echotexture and vascularity and the majority are intratesticular. Color Doppler analysis shows less extensive vascularity (compared to splenogonadal fusion) with irregular, fragmented, disintegrated vascular patterns in testicular mass, it may indicate cancer 12. Contrast-enhanced ultrasound (CEUS) improves the diagnostic process by demonstrating significant atrial phase in the ectopic splenic tissue. In continous splenogonadal fusion, computed tomography (CT) shows the connection of the cord between the testis and spleen and delineate the vascular structure arising from the splenic hilum¹³. Magnetic resonance imaging of the pelvis and abdomen improves the identification of Splenogonadal Fusion due to its excellent tissue spatial resolution, helping to distinguish between continuous and discontinuous type data. In splenogonadal fusion, the signal intensity and enhancement pattern will correspond to that of normal spleen. Magnetic resonance imaging can distinguish splenogonadal fusion from other types of cancer because of the adherence of ectopic tissue to testicular tissue, which the surroundings fat planes however in our case the MRI findings were not conclusive because of the non-familiarity of this entity, and it was not considered in the differential diagnosis.

Tissue Biopsy is the most accurate method to diagnose this condition. Histopathological examination of splenogonadal fusion showed normal splenic tissue including capsule, cortex, medulla, red pulp, white pulp and sinusoids (like the presenting case). Ectopic splenic tissue may present as thrombosis, calcification, fatty deterioration and hemosiderin deposition. There are few reports of the combination of spleen and gonad tissue.^1,7

Treatment decisions are often influenced by factors such the location of the ectopic splenic tissue, involvement of adjacent structures, patient age, symptoms, tumor characteristics, and expertise of the surgical team Numerous studies have utilised an orchidopexy technique for the treatment of splenogonadal fusion. Chen et al. have described a two-stage laparoscopic Fowler–Stephen orchidopexy, suggesting it as a feasible surgical option when conventional single-stage orchidopexy is not suitable ¹⁴. The primary goal of these surgeries is to preserve testis function unfortunately in our case it was treated by orchidectomy as it was thought it was a malignant tumor.

3. Conclusion

Splenogonadal Fusion is a rare congenital anomaly that is often misdiagnosed as a testicular tumor and other conditions. Accurate diagnosis enables suitable treatment planning, thus averting unnecessary radical orchiectomy, which can considerably impact the patient's reproductive and psychological health. Continued research is crucial for improving understanding of this uncommon condition and establishing standardised diagnostic and treatment protocols.

CRediT authorship contribution statement

Hajem Mohammad Ali Abu Dalou: Supervision. Hasan N. Al-Haidari: Writing – review & editing, Writing – original draft. Tasneem Naser Al-Malahmeh: Resources. Monther Al Momani: Resources. Ahmad Abed Alkareem Rjoub: Resources. Jihad Refat ( Mohammad Mahmoud) Asaad: Resources.