Physiological leukorrhea: This is a common and normal condition in prepubertal girls, caused by the influence of maternal estrogen levels, leading to a thin, white or brownish discharge. It's a self-limiting condition that resolves on its own.

Vaginal foreign body: Young girls may insert small objects into their vagina, leading to a foul-smelling, brown discharge. This condition requires prompt medical attention to remove the object and prevent further complications.
Vaginitis: Inflammation of the vagina can cause a brown discharge, and it's often associated with itching, redness, and irritation. The most common cause is bacterial vaginosis, but yeast infections and trichomoniasis can also occur in pediatric patients.
Poor hygiene: Inadequate cleaning of the genital area can lead to the accumulation of bacteria, dead skin cells, and other debris, resulting in a brown discharge.

Sexual abuse: Although rare, sexual abuse is a critical diagnosis that must be considered in cases of unusual or unexplained genital discharge in pediatric patients. A thorough medical and social evaluation is necessary to rule out this possibility.
Gonorrhea or chlamydia: These sexually transmitted infections (STIs) can cause a brown discharge in pediatric patients, especially in those who have been sexually active or abused.

Tumor or cyst: Rarely, a brown discharge in pediatric patients can be a sign of a vaginal tumor or cyst, such as a sarcoma botryoides (a type of rhabdomyosarcoma) or a vaginal cyst.
Endometriosis: Although extremely rare in prepubertal girls, endometriosis can cause a brown discharge, especially if there's a family history of the condition.
Shigella or other bacterial infections: Certain bacterial infections, such as Shigella, can cause a brown discharge in pediatric patients, especially in those with a history of recent travel or exposure to contaminated food or water.