Laparoscopic extraction of a giant peritoneal loose body: Case report and review of literature.

INTRODUCTION: A peritoneal loose body is a rare finding and is sometimes founded incidentally during laparotomy or autopsy. A giant peritoneal loose body, measuring more than 50mm, is very rare, and only a few cases of laparoscopic extraction of these giant bodies have been reported in the literature. PRESENTATION OF CASE: A 70-year-old man presented for evaluation of urinary frequency. He had no history of previous abdominal surgery or trauma. Computed tomography of the abdomen and pelvis showed a giant oval-shaped mass with calcification of the luminal core, measuring 58mm in diameter. Magnetic resonance imaging revealed a lesion with low intensity in T1-/T2-weighted images. Exploratory laparoscopy was performed. During the procedure, a yellow-white, oval-shaped mass with a "Boiled egg" appearance was discovered in front of the rectum. The mass was freely floating in the peritoneal cavity, without attachment to any intraperitoneal organs. The giant peritoneal loose body was extracted through a small incision, using an enlarged trocar site. DISCUSSION: Most peritoneal loose bodies are small, not exceeding 2cm in diameter, and are asymptomatic. Only a few cases of giant peritoneal loose bodies exceeding 5cm have been reported.
CONCLUSION: A giant peritoneal loose body is very rare and laparoscopic extraction was a useful technique. We report a case of a giant peritoneal loose body and review previously published series.

Introduction

A peritoneal loose body (PLB), also referred to as a “peritoneal mouse”, is a rare finding, but is sometimes observed during laparotomy or autopsy by accident [1]. In most cases, PLBs are usually less than 1 cm in size [2]. Giant loose bodies measuring more than 5 cm, are very rare, and only a few cases have been reported in the literature. We report a 70-year old male with a giant PLB in the pelvic cavity, with extraction by laparoscopic surgery. We also review of the previous published reports of giant PLB. This work has been reported in line with the SCARE criteria [3].

Presentation of case

A 70-year-old man had been admitted to our hospital for evaluation of urinary frequency. He had no history of previous abdominal surgery or trauma. He had also no family history or drug history. No abnormality was found on physical examination including digital rectal examination. Tumor markers and other laboratory tests were within the normal range.

Computed tomography (CT) showed an oval-shaped lesion measuring 58 mm in diameter, with calcification of the luminal core (Fig. 1A, B). Magnetic resonance imaging (MRI) showed a lesion that shared a margin with the rectum, and that had signal intensity similar to that of nearby muscle tissues. The lesion showed low intensity in T1-/T2-weighted images (Fig. 2A, B). CT and MRI revealed no enhancement in the mass. Colonoscopy and barium enema showed no evidence of a tumor or inflammatory bowel disease, and only slight external compression of the rectum was observed.

Fig. 1

Abdominal enhanced computed tomography. (A) Axial image showed a 50-mm nonenhanced mass with a central calcification. (B) Sagittal image showed the mass adjacent to the rectum in the pelvic cavity.

Fig. 2

Magnetic resonance imaging findings. (A), (B) Both T1- and T2-weighted images showed a low-intensity mass with the same degree of intensity as muscle tissue.

Based on the preoperative imaging findings, a giant PLB was strongly suspected. However, neoplastic disease such as teratoma, leiomyoma, or stromal tumor could not be ruled out, and exploratory laparoscopy was performed.

We planned reduced-port surgery, using only 1 port and 2 port-less small needle forceps. Initially, a 12-mm trocar was placed at the umbilicus. Then, 2 needle forceps device, (Endo Relief; Hope Denshi, Chiba, Japan) with 2.4-mm diameter shafts, requiring no trocars, were inserted at the right upper and lower quadrants.

On exploration, a yellow-white, oval-shaped mass was discovered in the pelvic cavity, between the rectum and the urinary bladder (Fig. 3A). It was completely separated from the intraperitoneal organs, and resembled a “boiled egg.” With the confirmed diagnosis of a giant PLB, the mass was placed into an endoscopic retriever bag (Fig. 3B) and taken out through the enlarged trocar site in the navel. The cut surface of the mass showed a bony-hard and smooth surface; with central calcareous deposition, the cut surface had the appearance of a typical boiled hen’s egg, with a whitish exterior and a yellowish interior core (Fig. 4A).

Fig. 3

(A) Laparoscopic surgery revealed an oval-shaped peritoneal loose body lying completely free in the pelvic cavity. (B) The loose body was placed in an endoscopic retriever bag and extracted from an enlarged port site.

Fig. 4

Extracted specimen. (A) The peritoneal loose body, measured 65 mm, was white and oval-shaped, and had a bony-hard and slightly glossy surface. (B) Histological examination revealed a necrotic fatty lesion in the central position, surrounded by layers of collagenous fibers.

Histologically, the mass included central fat necrosis and calcareous deposition over which fibrosis tissue formed a thin layer. There was no epithelial component in the mass (Fig. 4B).

The patient recovered well postoperatively. He was discharged from the hospital 3 days after surgery and the urinary frequency resolved immediately after removal of the mass.

Discussion

Giant PLBs are rare and few have been described. The pathogenesis of PLBs is not unclear; however, it is widely believed that the most common cause of a PLB is the chronic torsion of an epiploic appendix, followed by ischemia, saponification, and calcification. The epiploic Appendix finally detaches from the colon and becomes a PLB [2], [4]. Over time, the size of the PLB gradually increases because of protein deposition from peritoneal serum [5], similar to “a pearl inside an oyster.” Our histological findings supported this hypothesis, as the PLB had a central yellowish portion consistent with a calcified epiploic appendix, and surrounding layered white laminated fibroid material, hence giving the appearance of boiled egg. Rare cases of PLBs supported other etiologies. In women, PLBs with origin from auto-amputated adnexa, ovary, or uterine leiomyoma, have been reported [6], [7], [8].

Giant PLBs measuring more than 5 cm are very rare, and only a few cases have been reported. A literature search found 20 cases of giant PLBs (Table 1) [1], [2], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21]. Interestingly, as in our case, most giant PLBs occurred in men over age 50; three female cases were reported. These 3 cases may have had different pathogenesis from the other 17. As noted, these 3 female cases reportedly developed from auto-amputated adnexa or a uterine leiomyoma. In other words, giant PLBs resembling a boiled egg have only been described in male patients. This gender difference in the incidence of giant PLBs has not previously been reported. We speculate that the differences in the amount of visceral fat or hormones might be involved in the mechanism of PLB enlargement.

Table 1

Reported cases of giant peritoneal loose bodies in the literature.

Author	published year	Gender	Age	Chief complaint	Size of PLB(mm)	Surgical procedure	Complication	Discharge
Shephered JA [9]	1951	M	79	Acute retention of urine	70	Open	Bronchitis	ND
Bhandarwar AH [10]	1996	M	65	Acute retention of urine	90	Open		ND
Takada A [2]	1998	M	79	Evaluation of serum prostatic specific antigen	70	Open		ND
Nomura H [4]	2003	M	63	Incidental	50	Laparoscopy		ND
Ghosh P [11]	2006	M	63	Intestinal obstruction	58	Open	Bowel obstruction	ND
Mohri T [12]	2007	M	73	Abdomial pain	95	Open		POD7
Hedawoo JB [13]	2010	M	65	Abdomial pain	95	Open	Haemorrhoids	ND
Sewkani A [5]	2011	M	64	Abdomial pain	70	Open	Bowel obstruction	POD5
Jang JT [14]	2012	M	60	Dyspepsia	45	Laparoscopy		ND
Kim HS [1]	2013	M	50	Incidental	75	Laparoscopy		POD5
Rubinkiewicz M [6]	2014	F	70	Nausea	200	Open	Bowel obstruction, Intestinal perforation	ND
Sahadev R [15]	2014	M	52	Abdomial pain	70	Laparoscopy		POD4
Makineni H [16]	2014	M	52	Abdominal discomfort	60	Open		ND
Zhang H [17]	2015	M	51	Incidental	50	Laparoscopy		POD2
Sussman R [18]	2015	M	52	Urinary frequency	100	Laparoscopy		ND
Suganuma I [7]	2015	F	35	Incidental	75	Laparoscopy		ND
Lee KH [8]	2016	F	61	Abdomial pain	60	Laparoscopy		ND
Elsner A [19]	2016	M	52	Abdomial pain	52	Laparoscopy		POD3
Rosic T [20]	2016	M	73	Retention of urine	66	Laparoscopy		POD2
Huang Q [21]	2017	M	79	Urinary frequency	104, 76	Laparoscopy		POD3
Present case	2017	M	70	Urinary frequency	58	Laparoscopy		POD3

ND not determined, NR not recorded, POD post operative day.

Small PLBs are usually asymptomatic; however, giant PLBs can cause acute or chronic symptoms due to extrinsic compression of the viscera [9]. Of 21 giant PLBs, 17 (80.9%) were symptomatic, with the most common symptom being abdominal pain or discomfort (7 of 21 cases, 33.3%), followed by urinary retention or frequency (6 of 21 cases, 28.5%), as in our case. There were 2 reported cases with lethal complications requiring emergency surgery, due to intestinal obstruction or perforation.

Possibly due to the rarity of giant PLBs, correct preoperative diagnosis is difficult, and was reported in only one case [12]. PLBs tend to migrate into the pelvis, and the differential diagnosis includes a dermoid, teratoma, leiomyoma, calcified uterine fibroid, ovarian cyst, or tubercular granuloma [2]. CT and MRI can be performed to distinguish PLBs from other pathologies. CT of a PLB shows a concentric, round or oval, well-defined mass with central calcification, surrounded by a peripheral soft tissue density [2]. On MRI, a PLB appears as a well-circumscribed, low-intensity mass on both T1- and T2- weighted images. The MRI signal is similar to that of muscle, and a central high-intensity area may be seen on T1-weighted images [2]. PLBs do not exhibit any enhancement; this is useful in the process of discrimination, because contrast enhancement occurs in leiomyoma and teratomas [4].

If PLB is only found radiologically, surgery is normally not necessary; however, in cases of giant PLBs, we advocate the importance of surgical intervention for the purpose of diagnosis and extraction. First, giant PLBs are more likely to cause symptoms that are sometimes acute and life-threatening. Second, other disease may not be fully excluded by radiological imaging alone, and surgical exploration might be necessary for definitive diagnosis.

In this instances, laparoscopy is useful for simultaneous diagnosis and treatment. Laparoscopy reduces surgical trauma and provides better cosmesis. Less surgical invasion results in a shorter hospital stay, and reduces the risk of late complications of laparotomy, such as incisional hernia, or intestinal obstruction it caused by adhesions.

In our case, a giant PLB could be removed laparoscopically through a smaller incision; the patient’s hospitalization was short and his urinary frequency resolved immediately after the surgery.

Conclusion

A giant PLB is rare condition and surgical removal is recommended, because serious complications sometimes occur. Laparoscopy is the best choice for treatment; because of diagnostic yields, decreased invasiveness, and better cosmesis.

Conflict of interests

The authors have no conflicts of interest.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Ethical approval

Ethical approval was not required and patient identifying knowledge was not presented in the report.

Consent

Written informed consent has been obtained from the patient for the publication of this case report and any accompanying images.

Authors’ contribution

KM and YT participated in treatment of the patient, collected case details, literature search and draft the manuscript. TN performed the pathological analysis. SI and TU participated in treatment planning of the patient. TI participated in treatment planning of the patient and helped to draft the manuscript. All authors read and approved the final manuscript.

Registration of research studies

This study was performed in accordance with the Declaration of Helsinki.

Guarantor

Yuji Takakura