Altogether when the aforementioned conditions occur, it is called transverse testicular ectopia.Under the microscope, some samples taken for biopsies displayed results where testicular tissue was at a stage of immaturity, and showed dysplasia. Genetics
Mutation in AMH gene (PMDS Type 1) or AMHR2 gene (PMDS Type 2) are the primary causes of PMDS. AMH, or sometimes referred to as Müllerian inhibiting substance (MIS), is secreted by Sertoli cells during an individuals whole life. It is essential during the foetal period as it functions to regress the Müllerian ducts. However, AMH also functions in the last trimester of pregnancy, after birth, and even during adulthood in minimal amounts. The Sertoli cells in males secrete AMH, through the presence of a Y chromosome.The role of the AMH gene in reproductive development, is the production of a protein that contributes to male sex differentiation. During development of male foetuses, the AMH protein is secreted by cells within the testes. AMHs bind to the AMH Type 2 Receptors, which are present on cells on the surface of the Müllerian duct. The binding of AMH to its receptors on the Müllerian duct induces the apoptosis of the Müllerian duct cells, thus the regression of the Müllerian duct within males. However, for females who originally do not produce AMH proteins during foetal development, the Müllerian duct eventually becomes the uterus and fallopian tubes as normal.
They may also show the underlying cause and the extent to which the disease has progressed. Treatment
Several methods of treatment are available, mainly consisting of careful drug therapy and surgery. Glucocorticoids (such as prednisone or methylprednisolone) decrease the inflammatory response to tumor invasion and edema surrounding the tumor. Glucocorticoids are most helpful if the tumor is steroid-responsive, such as lymphomas. In addition, diuretics (such as furosemide) are used to reduce venous return to the heart which relieves the increased pressure.In an acute setting, endovascular stenting by an interventional radiologist may provide relief of symptoms in as little as 12–24 hours with minimal risks.Should a patient require assistance with respiration whether it be by bag/valve/mask, bilevel positive airway pressure (BiPAP), continuous positive airway pressure (CPAP) or mechanical ventilation, extreme care should be taken. Increased airway pressure will tend to further compress an already compromised SVC and reduce venous return and in turn cardiac output and cerebral and coronary blood flow. Spontaneous respiration should be allowed during endotracheal intubation until sedation allows placement of an ET tube and reduced airway pressures should be employed when possible. Prognosis
Symptoms are usually relieved with radiation therapy within one month of treatment. However, even with treatment, 99% of patients die within two and a half years. This relates to the cancerous causes of SVC found in 90% of cases. The average age of disease onset is 54 years. See also
Pembertons sign

References
Further reading
Wilson LD, Detterbeck FC, Yahalom J (May 2007). "Clinical practice. Superior vena cava syndrome with malignant causes". N Engl J Med.