A rare cyst in a rare location in a 20 year old female

This 20 year old female came for non specific complaints. Ultrasound imaging revealed these images:

We put a diagnosis of presumed urachal cyst. 

It was midline in location and showed no septae or particulate matter. Clear fluid content and contiguous with anterior abdominal wall as well as the urinary bladder. This prompted us to put a possible diagnosis of urachal cyst. 

Agreed it's pretty large at 3.4 cms. But the midline location also supports our diagnosis. 

So, what are the typical ultrasound findings in urachal cyst:

On ultrasound imaging, a urachal cyst typically appears as a fluid-filled, spherical or oval-shaped mass in the lower abdominal area, near the umbilicus. The cyst may be single or multiple and may vary in size, ranging from a few millimeters to several centimeters in diameter.

The cyst usually has a thin, smooth wall and contains clear or slightly echogenic (reflective) fluid. It may also have internal echoes, which can indicate the presence of debris or blood within the cyst.

In some cases, the urachal cyst may be associated with inflammation or infection, which can cause the cyst wall to become thicker and more irregular in appearance. In severe cases, the cyst may rupture, causing leakage of its contents into the surrounding tissues and potentially leading to peritonitis (inflammation of the abdominal lining).

In addition to the cyst itself, the ultrasound exam may also reveal other findings, such as the presence of associated abnormalities in the bladder or nearby structures. These may include a patent urachus (a persistent communication between the bladder and umbilicus), an umbilical hernia, or an enlarged bladder due to obstruction or other causes.

Final diagnosis: urachal cyst 

So what are the differential diagnoses here?

If the cyst appears separate from the ovaries, then it is less likely to be an ovarian cyst. Here are some additional possibilities:

Peritoneal cyst: A peritoneal cyst is a fluid-filled sac that develops in the lining of the abdominal cavity. They are usually benign and asymptomatic, but they can grow large and cause discomfort or pain.

Para-adnexal cyst: A para-adnexal cyst is a fluid-filled sac that develops in the tissue next to the uterus and ovaries. They are usually benign and asymptomatic.

Hydrosalpinx: A hydrosalpinx is a fluid-filled dilation of the fallopian tube. It can occur as a result of infection, inflammation, or endometriosis.

Lymphocele: A lymphocele is a fluid-filled sac that develops in the lymphatic system. They are usually benign and asymptomatic.

So what are urachal cysts and prognosis, treatment etc?

A urachal cyst is a rare condition that occurs when the urachus, a tube-like structure that connects the bladder to the umbilicus during fetal development, fails to close properly after birth.

Urachal cysts are more common in males than females, and typically present in the third or fourth decade of life.

Symptoms of a urachal cyst may include abdominal pain, swelling, and a palpable mass.

Diagnosis is typically made through imaging studies such as ultrasound or computed tomography (CT) scan.

Treatment typically involves surgical removal of the cyst, as there is a risk of infection or malignancy if left untreated.

In this particular case, a 3.5 cm urachal cyst was discovered in a 20-year-old female through ultrasound imaging.

Depending on the patient's symptoms and other clinical factors, the cyst may be monitored or surgically removed.

Long-term follow-up may be necessary to ensure the cyst does not recur or develop complications.

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Sonography of urachal cyst and urinary bladder