What’s your most likely diagnosis?
Correct answer is bartholin gland cyst
Key points 
Bartholin glands are located on both sides of the vaginal opening in the labia minora
The glands secrete thin lubricating mucus during sexual excitation
Blockage of the gland and duct can lead to cyst formation due to the accumulation of a mucoid substance
Symptoms include vulval swelling and tenderness
The cyst can be asymptomatic or symptomatic and can lead to formation of an abscess
A Bartholin abscess is an acute bacterial infection usually associated with an E coli, staphylococcal, or polymicrobial infection
Epidemiology
Incidence and prevalence:
Bartholin cyst develops in 2% of women
Demographics:
Bartholin cyst may occur in any age group, especially in women aged 20 to 50 years
Occurs in female patients only
Increased incidence in patients who have had sexually transmitted diseases (STDs) or sexual trauma
Causes and risk factors
Causes:
Obstruction of the glandular drainage is the common denominator of cyst and/or abscess formation
Rare causes include gonorrhea; Mycoplasma hominis; and cancer, which usually occurs only in women older than age 40 years
Risk factors:
Colonization with organisms such as E coli and staphylococci
Exposure to STDs
Previous cyst or abscess formation of the Bartholin glands
Previous surgery or injury in the vaginal area
Previous or current infection in the vagina