Teaching Case

A seventeen-month-old female patient presented to the emergency department with a three-day history of anorexia and intermittent abdominal pain. She initially had several bouts of non-bilious emesis that resolved after one day.
On abdominal examination there was mild distension and diffuse tenderness. Rectal examination was negative for occult blood.

An ultrasound was performed and demonstrated a cystic abdominal mass. There was concern of acute abdomen, so a CT was performed and a complex cystic abdominal mass in the midline was seen, with fat areas and focal calcification, compatible with mature teratoma of the right ovary (Fig. 1). The fallopian tube was also thickened on the affected side, suggestive of ovarian torsion (Fig. 2).

Ovarian mature cystic teratomas are among the most common ovarian tumours, constituting 20% of all ovarian tumours in adults and 50% of all ovarian tumours in children [1], and are composed of mesodermal and endodermal elements.
Uncomplicated teratomas are mostly asymptomatic and often discovered incidentally. As they predispose to ovarian torsion [2], they may present with acute pelvic pain.
CT has high sensitivity in the diagnosis of cystic teratomas [3]. Typically CT images demonstrate fat (areas with very low Hounsfield values), fat fluid level, calcification (sometimes tooth), Rokitansky protuberance and tufts of hair. On CT, fat attenuation within a cyst, with or without calcification in the wall, is diagnostic for mature cystic teratoma [4].
They are slow growing tumours and therefore some advocate non-surgical management. Larger lesions are often surgically removed, as they are more prone to complications [5].
Ovarian torsion is usually associated with a cyst or tumour, which is typically benign; the most common being the mature cystic teratoma [7].
Common CT findings of ovarian torsion are somewhat nonspecific and include an adnexal mass that may be in the midline or rotated toward the contralateral side of the pelvis, deviation of the uterus to the side of the affected ovary, and ascites [6, 8]. Thickened fallopian tube can also be seen [6].
The diagnosis can also be done with MRI, which doesn't expose the patient to radiation, however, it is not easily accessible on most institutions in an emergency setting.
Diagnosis of ovarian torsion continues to be a difficult task requiring awareness and a high degree of suspicion. The treatment is immediate surgery, as preservation of fertility is the crucial principle [9].
The most consistent finding is a unilateral enlarged ovary, without which the diagnosis is unlikely to be ovarian torsion [8].