Splenogonadal fusion

File:Cureus-0012-00000009017-i03.jpg

Splenogonadal fusion is separated into two types:

• Continuous (55%): The native spleen is connected to the gonad. The connection occurs through a cord of splenic tissue or fibrous band.
• Discontinuous (45%): Ectopic splenic tissue is present and attached to the gonad. An accessory spleen is present and the native spleen lacks the direct attachment to the gonad.

The cause of splenogonadal fusion is still unclear, and there are several proposed mechanisms. A developmental field defect that occurs during blastogenesis is the current explanation of pathogenesis. The spleen derives from mesenchymal tissue and an inappropriate fusion can happen between the gonadal ridge during gut rotation, which occurs between weeks 5 and 8 of fetal life.{{cite journal |last1=Chiaramonte |first1=C |last2=Siracusa |first2=F |last3=Li Voti |first3=G |title=Splenogonadal Fusion: A Genetic Disorder?-Report of a Case and Review of the Literature. |journal=Urology Case Reports |date=March 2014 |volume=2 |issue=2 |pages=67–9 |doi=10.1016/j.eucr.2014.01.003 |pmid=26952691|pmc=4733014 }} Splenogonadal fusion may result from an unknown teratogenic insult. The timing of this insult may correlate to the severity of associated defects. There is also postulation that fusion may occur due to adhesion after an inflammatory response or a lack of apoptosis between the structures. Siblings documented to have splenogonadal fusion and an accessory spleen provides additional evidence of a possible genetic component.

Additional congenital abnormalities are most often found associated with the continuous type of splenogonadal fusion. These abnormalities include micrognathia, macroglossia, anal atresia, and pulmonary hypoplasia.{{cite journal |last1=McPherson |first1=F |last2=Frias |first2=JL |last3=Spicer |first3=D |last4=Opitz |first4=JM |last5=Gilbert-Barness |first5=EF |title=Splenogonadal fusion-limb defect "syndrome" and associated malformations. |journal=American Journal of Medical Genetics. Part A |date=1 August 2003 |volume=120A |issue=4 |pages=518–22 |doi=10.1002/ajmg.a.10728 |pmid=12884431|s2cid=40127231 }} The most commonly associated malformation is cryptorchidism. When limb abnormalities occur, Splenogonadal Fusion with Limb Defects is made as a separate diagnosis. Splenogonadal Fusion with Limb Defects is also of unknown cause but some literature suggests that the condition may be related to Hanhart syndrome and facial femoral syndrome. Splenogonadal fusion has also been identified in infants with Möbius syndrome and Poland syndrome.{{cite journal |last1=Cabrera Viteri |first1=MI |last2=Acosta Farina |first2=D |last3=Morales Mayorga |first3=H |last4=Cabrera Johnson |first4=M |last5=Albán Castro |first5=S |title=Splenogonadal fusion associated with Moebius and Poland syndromes: first case reported. |journal=Cirugia Pediatrica |date=1 October 2021 |volume=34 |issue=4 |pages=219–222 |pmid=34606704}}

Diagnosis can be challenging pre-operatively, as patients are commonly asymptomatic. Physical examination can aid in diagnosis if the mass is palpated, but further confirmatory tests are necessary. Females are reportedly less affected by splenogonadal fusion, though it is possible that the condition is underdiagnosed due to the difficulty of internal gonad examination in females. On scrotal ultrasound, ectopic splenic tissue may appear as an encapsulated homogeneous extratesticular mass, isoechoic with the normal testis. Subtle hypoechoic nodules may be present in the mass. Limitations of doppler ultrasonography include visualizing the nonspecific paratesticular masses which can mimic malignancies such as rhabdomyosarcoma or embryonal sarcoma.{{cite journal |last1=Akbar |first1=SA |last2=Sayyed |first2=TA |last3=Jafri |first3=SZ |last4=Hasteh |first4=F |last5=Neill |first5=JS |title=Multimodality imaging of paratesticular neoplasms and their rare mimics. |journal=Radiographics |date=November 2003 |volume=23 |issue=6 |pages=1461–76 |doi=10.1148/rg.236025174 |pmid=14615558}} Technetium-99m sulfur colloid scan is sensitive to target the liver, spleen, and bone marrow, therefore the scans can be used to identify ectopic splenic tissue when clinical suspicion is high.{{cite journal |last1=Daghas |first1=FA |last2=Asiri |first2=JA |last3=Hassine |first3=H |last4=Ibrahim Aamry |first4=A |title=^99mTc-Sulfur Colloid SPECT/CT in Diagnosis of Splenogonadal Fusion. |journal=Journal of Nuclear Medicine Technology |date=March 2022 |volume=50 |issue=1 |pages=75–77 |doi=10.2967/jnmt.121.262233 |pmid=34750231|s2cid=243862063 |doi-access=free }} When technetium-99m sulfur colloid scans are not included in a patient's diagnostic workup, the diagnosis is often not made until the surgeon performs an abdominal exploration using laparoscopy which can visualize the splenic tissue grossly. Evaluation by biopsy including frozen section procedure is confirmatory for splenogonadal fusion. Histological examination will show normal splenic tissue which is made up of red and white pulp.{{cite journal |last1=Fadel |first1=MG |last2=Walters |first2=U |last3=Smith |first3=A |last4=Bedi |first4=N |last5=Davies |first5=C |last6=Brock |first6=C |last7=Dinneen |first7=M |title=Splenogonadal fusion: aiding detection and avoiding radical orchidectomy. |journal=Annals of the Royal College of Surgeons of England |date=19 March 2021 |volume=104 |issue=2 |pages=e32–e34 |doi=10.1308/rcsann.2021.0080 |pmid=33739169|s2cid=232298023 |pmc=10335196 }} Many people with splenogonadal fusion go undiagnosed without complication during their lifetime. Many cases have been diagnosed at autopsy or incidentally after orchiectomy.

Treatment remains controversial given the benign nature of splenogonadal fusion. Splenogonadal fusion does not have known clinical manifestations that require intervention. Clinical observation is considered when the mass is diagnosed pre-operatively. Surgery is often required to confirm the diagnosis and exclude a mimic of a malignant mass. Surgical approach should attempt to divide the mass and the gonad at the connecting plane for removal of the splenic tissue. Orchiectomy is generally not indicated. Causality between splenogonadal fusion and future malignant transformation has not been established, but literature has highlighted infrequent cases of testicular neoplasms and splenogonadal fusion. These cases were found in patients who also had a history of cryptorchidism, which is a known risk factor for testicular cancer.{{cite journal |last1=Kadouri |first1=Y |last2=Carnicelli |first2=D |last3=Sayegh |first3=HE |last4=Benslimane |first4=L |last5=Nouini |first5=Y |title=Pathogenesis, Diagnosis, and Management of Splenogonadal Fusion: A Literature Review. |journal=Case Reports in Urology |date=2020 |volume=2020 |pages=8876219 |doi=10.1155/2020/8876219 |pmid=33101755|pmc=7568155 |doi-access=free }}

• Splenogonadal fusion-limb defects-micrognathia syndrome

{{reflist}}

Category:Developmental biology

Category:Congenital disorders of genital organs