Deciding to Remove or Leave a Peritoneal Loose Body: A Case Report and Review of Literature

Background

Peritoneal loose bodies (PLBs), also known as “peritoneal mice”, are uncommon small lesions found incidentally during exploration or autopsy with few cases reported in the literature. The presentation can be very nonspecific and can present a diagnostic dilemma requiring sophisticated radiological investigations; even then, it is often diagnosed intra-operatively. It is interesting to note that of all cases in the literature, only 1 case was diagnosed preoperatively [1]. Commonly, they present with mild or no symptoms; however, there are reports of serious presentations such as bowel obstruction or perfo-ration. Earlier cases were treated by laparotomy, but with the introduction of minimally invasive surgery, a number of cases have been managed laparoscopically. We report a case of a giant peritoneal loose body presenting with urinary symptoms and abdominal pain.

Case Report

A 58-year-old man known to have diabetes mellitus type II and hypertension presented to our hospital Emergency Department with complaints of bilateral flank pain and fever of 3-day duration associated with dysuria and hematuria. He had no other relevant gastrointestinal symptoms and no history of trauma or surgery.

On examination, he was vitally stable but febrile with right iliac fossa and bilateral flank tenderness. Blood tests showed raised leukocyte count and a urine dipstick test was positive for blood and leukocytes. An abdominal non-contrast CT was performed, which showed a well-circumscribed lesion with calcification in the right lower quadrant measuring approximately 4.9×4.1 cm (Figure 1). Multiple areas of calcification were noted in the liver and tiny gravel was noted in the right kidney. There was no evidence of hydronephrosis or mass lesion of the kidneys.

For further characterization of the lesion, the patient underwent a CT abdomen and pelvis with contrast, showing that the lesion was now located on the left side of the pelvis, with some impression on the left posterior superolateral wall of the urinary bladder (Figure 2), and it also revealed multiple areas of very high density in the liver and spleen.

Given the possibility of a mobile intra-abdominal mass, informed consent for exploratory laparoscopy was obtained and the patient underwent laparoscopy. On diagnostic laparoscopy, we found a hard, oval-shaped mass freely mobile in the pelvic cavity (Figure 3) and 2 small, calcified lesions also were seen in the falciform and ileocecal junction. The lesion was laparoscopically retrieved and sent for histopathology. The patient had an uneventful postoperative course with complete resolution of his symptoms.

Macroscopically, the mass was oval in shape and firm, measuring 6×4.8×4.2 cm, with a smooth, white surface (Figure 4). Cut surfaces reveal tan-yellow, firm material with a focally calcified center (Figure 5). Histologically, the mass consisted of hyalinized and calcified tissue with fat necrosis, most likely representing an infarcted appendix epiploicae.

The patient had an uneventful postoperative course with complete resolution of his symptoms. He was discharged from the hospital on the following day.

Discussion

CLINICAL PRESENTATIONS:

In most cases, peritoneal loose bodies are asymptomatic, but giant bodies can present with various symptoms secondary to compression, as in intestinal obstruction, urinary retention, or urinary tract infection (UTI) [3,4]. Interestingly, our patient presented with urinary tract symptoms, including macroscopic hematuria, which was not reported before in the literature. Common causes of hematuria include urinary tract calculi and UTI, as well as urinary tract malignancies, which are typically painless [9]. In our case, we hypothesized that chronic irritation by PLB led to urinary tract infection and hematuria. However, as the symptoms were acute and totally resolved after surgery, he was referred to urology, so we cannot trace the patient for further investigations and, hence, the hematuria may or may not be related to PLB.

Peritoneal loose bodies can present a diagnostic dilemma to the surgeon and are rarely diagnosed preoperatively, but it was suggested that additional scanning of the patient in the prone position or a follow-up imaging study can demonstrate mobility of a loose body and can help in the diagnosis [10].

RADIOLOGICAL FEATURES:

On ultrasound, PLB manifests as a mobile, hypoechoic, round mass with wide lateral shadowing [11]. CT, however, shows a round or oval-shaped, well-defined mass with central calcification, surrounded by peripheral soft tissue [12]. It also shows no fluorodeoxyglucose (FDG) uptake on positron emission tomography (PET) scan and no enhancement with contrast, which can be helpful in differentiating PLBs from leiomyomas and calcifying fibrous pseudotumors [10,13].On T1- and T2-weighted magnetic resonance imaging, PLB appears as a low-intensity mass comparable to muscle tissue or collagen fiber, with a central high-intensity on T1-weighted images [14].

Conclusions

Loose peritoneal bodies can present a challenging diagnostic problem to the surgeon, with confusing findings that can point towards malignancy. It often requires a number of investigations, but even with these investigations, operative exploration, either open or laparoscopic, can be the ultimate diagnostic and therapeutic modality. The mobility of these calcified lesions may give a preoperative clue to the etiology. It is important to distinguish peritoneal loose bodies from neoplastic or metastatic lesions and to consider it in the differential diagnosis of a calcified mobile pelvic mass. Laparoscopic surgery is a safe and effective modality in the retrieval of symptomatic peritoneal loose bodies.