Persistent Müllerian duct syndrome

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Persistent Müllerian Duct Syndrome (PMDS) is a rare condition in genetically typical boys and men (46,XY) where female reproductive organs—the uterus and fallopian tubes—remain inside the body even though their bodies are otherwise male. This happens when the signal to break down the female ducts doesn’t work as it should before birth.

Causes
- PMDS is usually inherited in an autosomal recessive way (both parents are typically carriers and don’t have symptoms).
- Most cases come from mutations in either the AMH gene (PMDS Type I) or the AMHR2 gene, which creates the receptor AMH binds to (PMDS Type II).
- In about 15% of cases the cause is unknown (idiopathic).

How it develops
- In normal male development, Sertoli cells make anti-Müllerian hormone (AMH), which tells the Müllerian ducts to regress.
- If AMH is defective (Type I) or the receptors don’t work (Type II), the Müllerian ducts don’t disappear and female structures like the uterus and fallopian tubes persist.

Presentation
- The most common sign in babies is cryptorchidism (undescended testicles), sometimes on one side or both, and may be associated with an inguinal hernia.
- Some individuals may have a small uterus or other Müllerian tissues.
- In adults, symptoms can include blood in semen in rare cases; some people discover the condition during infertility workups or surgery.

Diagnosis
- Often found during hernia surgery or infertility evaluation.
- Ultrasound or MRI can show persistent Müllerian structures.
- Genetic tests can identify AMH or AMHR2 mutations.
- Hormone tests may show low AMH levels and sometimes low testosterone around puberty.

Treatment
- The main approach is surgery to position the testes in the scrotum (orchidopexy) and to remove Müllerian tissue if it can be done safely.
- Surgeons try to separate or remove Müllerian tissue from nearby structures to improve fertility chances.
- If the testes cannot be brought down, testosterone replacement may be needed at puberty.
- Minimally invasive laparoscopic approaches are increasingly used.

Prognosis and risks
- Infertility can be a concern if not treated, but timely surgery improves chances.
- There is a small risk that remaining Müllerian tissue could become cancerous, so removal is often considered.
- Early diagnosis and management help reduce complications.

Summary
PMDS is a rare, genetic condition in 46,XY males where the ducts that create female reproductive organs persist. It usually results from AMH or AMHR2 gene mutations, is inherited in an autosomal recessive pattern, and is managed mainly with careful surgery to place the testes and remove or separate Müllerian tissue.