The First Report of an Intraperitoneal Free-Floating Mass (an Autoamputated Ovary) Causing an Acute Abdomen in a Child

A free-floating intraperitoneal mass is extremely rare, and almost all originate from an ovary. Here, we present the first case with an intraperitoneal free-floating autoamputated ovary that caused an acute abdomen in a child and also review the literature. A 4-year-old girl was admitted with signs and symptoms of acute abdomen. At surgery, the patient had no right ovary and the right tube ended in a thin band that pressed on the terminal ileum causing partial small intestine obstruction and acute abdomen. A calcified mass was found floating in the abdomen and was removed. The pathological examination showed necrotic tissue debris with calcifications. An autoamputated ovary is thought to result from ovarian torsion and is usually detected incidentally. However, it can cause an acute abdomen.


Introduction
An autoamputated ovary (AO) is a very rare cause of an intraabdominal mass . The primary pathological event of an AO is torsion of a normal ovary or an ovarian cyst and the adnexa, followed by infarction and necrosis [17,21,26,27]. Typically, the AO is found incidentally while investigating an unrelated disease, on antenatal ultrasonography, or at surgery .
Here, we present a patient who underwent surgery for an acute abdomen and was observed to have a free-floating AO in the abdominal cavity. We also review the occurrence of this extremely rare free-floating mass in children and discuss its diagnosis and management. A 4-year-old girl was admitted with nausea, vomiting, and abdominal pain. On physical examination, the right lower abdominal quadrant was tender. Abdominal guarding and rebound were detected. The abdominal plain X-ray was normal. Emergency ultrasonography (US) showed minimal free fluid. The patient underwent surgery for an acute abdomen. At surgery, a 28 mm diameter, brown, soft, calcified mass was found floating in the right lower abdomen ( Figure 1). The patient had no right ovary and the right tube ended in a thin band that extended to the cecum and pressed on the terminal ileum causing partial small intestine obstruction and acute abdomen ( Figure 2). The appendix was hyperemic. The freefloating mass was removed from the abdomen, the right fallopian tube and band were excised, and an appendectomy was performed. The patient was discharged on the second postoperative day. The pathological examination showed long standing necrotic tissue debris with calcifications. The 6-year follow up showed no problems.

Discussion
A free-floating intraperitoneal mass is extremely rare, and almost all originate from an ovary. To date, there have been only two cases in the literature that originated from other organs [28,29]; one such mass in a geriatric woman was from the gallbladder, due to torsion, and caused acute abdomen, while the other was from appendix epiploica, due to torsion, 2 Case Reports in Surgery  in a man [28,29]. A free-floating intraperitoneal AO in a child was first reported by Lester and McAlister in 1970 [1]. Our case is the first report of an intraperitoneal free-floating mass causing an acute abdomen in a child.
There have been only 36 reported cases of intraperitoneal free-floating AO involving children ranging in age from 1 day to 12 years of age, including our case (Table 1) . Twenty-five cases were younger than 1 year of age. Although 23 of these infants were diagnosed with a cystic abdominal mass, ranging in diameter from 2.2 to 8 cm on antenatal US, only 12 of the newborns were operated on during the neonatal period.
Six cases were symptomatic, including our case. One of the newborns had abdominal distention, intestinal obstruction, and respiratory distress syndrome due to an 8 cm diameter cyst [24]. Four children, ages 14 and 17 months, 2 years, and 12 years, had a history of abdominal pain without an acute abdomen and were diagnosed during routine physical examinations [1,3,7]. Only our 4-year-old patient developed an acute abdomen, with signs and symptoms that included tenderness in the right abdominal quadrant, nausea, and vomiting.
Nine of the masses could be palpated on physical examination. Only three cases were diagnosed as an AO preoperatively. Characteristically, an AO is seen as a free-floating intraabdominal mass on antenatal US [13,19,25]. Eight cases were diagnosed incidentally. Two had no abdominal pain but were diagnosed based on palpating an abdominal mass during a routine physical examination [3]. The other six patients were diagnosed with a calcified mass seen on plain X-rays obtained for an unrelated reason [2,3,6,10,12]. The AO was the right ovary in 17 cases, the left in 11, bilateral in two, and unknown in six cases.
Ultrasonography is safe and sufficient for diagnosing most ovarian cysts and AO. Computed tomography and magnetic resonance imaging may be performed if the mass is complex [22]. In our case, emergency US showed minimal free fluid, but no AO, perhaps because our patient had an   We believe that this is because antenatal US is performed very commonly worldwide. Pathologically, necrosis was seen in all cases, and 20 had calcifications. Small amounts of ovarian tissue were seen in seven specimens [3,7,18,20,23,25]. In four of these cases, the AO was attached to the retroperitoneum and ascending colon by vessels [3], the omentum [23], the mesentery of the transverse colon via a long pedicle [7], or to the liver via a hemorrhagic twisted pedicle of omentum [7]. None contained malignant tissue. In adults, Ushakov et al. reported a remarkable characteristic of AO: an AO teratoma became reimplanted as an omental mass in 22 cases of teratoma of the omentum that they reviewed [26]. This adult review and our review of children suggest that an AO may reimplant, develop into omentum or peritoneum, and possibly undergo malignant transformation. Therefore, we suggest that all AOs should be excised instead of taking a wait and see approach.
An AO is very rare and thought to result from ovarian torsion. Most free-floating AOs are detected incidentally. However, clinicians should remember that it can cause an acute abdomen, and should always make sure there are two ovaries on US in a small child with acute abdomen.