Classification
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. Pathogenesis
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. 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. Associated Conditions
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. 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.
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. See also
Splenogonadal fusion-limb defects-micrognathia syndrome


== References ==