Rare cases imitating acute appendicitis: Three case reports and a review of literature

Overview

Acute appendicitis with its characteristic clinical course is one of the most common diagnoses that require urgent surgery. The following three case reports present patients with symptoms typical of acute appendicitis which was, however, not confirmed intraoperatively. Preoperative CT or MRI were not requested because symptoms clearly indicated acute appendicitis. The first case describes a male patient with right-sided diverticulitis, the second case report involves a pregnant woman in 33^rd week of gestation with right adnexal torsion due to a dermoid cyst, and in the last report, a case of spontaneous perforation of appendiceal mucinous neoplasm is presented.

Key words:
right-sided diverticulitis – dermoid cyst – adnexal torsion – mucinous neoplasm – pseudomyxoma peritonei – appendicitis

Introduction

Acute appendicitis (AA) is one of the most common causes for urgent surgery.

The lifetime incidence of AA is approximately 7% [1,2]. In recent studies, a decreasing rate in most countries worldwide has been reported [3–6]. The annual incidence varies from 75/100,000 in Ontario (Canada) [4], 94/100,000 in USA [7], 98/100,000 in Finland [5] to 107/100,000 in Taiwan [6].

The first-line treatment for AA is prompt surgical intervention. Therefore, surgery is sometimes performed for presumed appendicitis and a non-appendiceal and less common diagnosis is finally revealed.

Differential diagnosis of right iliac fossa pain includes a wide variety of conditions. Apart from AA, problems of gynaecological or urological origin, mesenteric lymphadenitis, infectious gastroenteritis, inflammatory bowel disease, cecal tumours etc. can be considered.

In differential diagnosis of right lower quadrant pain, we have recently encountered the following infrequent cases at our department: right-sided diverticulitis, adnexal torsion in late pregnancy and spontaneous perforation of an appendiceal mucinous neoplasm.

Right-sided diverticular disease is rare in the Western world with incidence being approximately 1–2% of all cases of colonic diverticulosis. However, the disease is more common in Asia where the incidence varies between 50–70% [8–11]. Preoperative diagnostics of acute right-sided diverticulitis (RSD) is challenging and the success rate is usually as low as 0−23% [12] due to symptoms similar to AA. Most diagnoses of RSD (70−90%) are made during surgery [12,13].

Right adnexal pathology can often mimic symptoms of AA. A clear distinction based on clinical examination or ultrasound is difficult. Moreover, pregnancy, particularly in its later stages, can make differential diagnosis of right iliac fossa pain even more demanding.

Dermoid cysts represent 20−40% of ovarian neoplasms discovered during pregnancies and can cause serious complications such as rupture, torsion, bleeding, infection, malignancy or obstructed labour [14–16]. The highest number of torsions occurs in the first, occasionally in the second and very rarely in the third trimester [16].

Appendiceal tumours are rare and can be found in less than 1% of the performed appendectomies [17,18]. Of these, low-grade appendiceal mucinous neoplasms (LAMN) represent only a minor subgroup [18]. Pseudomyxoma peritonei (PMP) is described as mucinous ascites or intraperitoneal mucin deposits containing variable numbers of neoplastic epithelial cells [19]. PMP mostly arise from appendiceal mucinous neoplasms [19,20].

Case report 1

Right-sided diverticulitis

A 39-year-old man was referred to our outpatient department with a two-day history of right iliac fossa pain without nausea or vomiting. The patient was known to have diabetes mellitus and had undergone left inguinal hernia repair. Clinical examination revealed signs of peritonitis in right lower quadrant and blood tests showed elevated inflammatory markers (CRP: 69 mg/l, WBC count: 12×10⁹/l). An ultrasound scan proved a thickened appendix wall as well as mild inflammatory changes in the caecum and ascending colon. The patient was admitted for a high suspicion of AA and laparoscopy was performed, however, with surprising findings. The appendix showed no inflammatory changes. On the contrary, initial stage of cecal diverticulitis was diagnosed (Fig. 1a, 1b). No severe complications were observed and therefore laparoscopic appendectomy was performed. During hospital stay, antibiotic therapy was administered and CT scans were done (Fig. 2a). The patient was discharged on the 6^th postoperative day with appropriate instructions and scheduled follow-up. Three months later, the patient was readmitted for abdominal pain with a WBC count of 17x10⁹/l and CRP of 250 mg/l. A repeat CT scan showed extensive diverticulitis of the caecum and the ascending colon with a forming abscess (fluid collection) (Fig. 2b). Laparoscopic revision was carried out and pericecal abscess, distant abscess in small pelvis and inflammatory adhesions between terminal ileum and caecum were found. All pus was aspirated, thorough lavage was performed and two drains were placed into the abdominal cavity (pericaecally and into the small pelvis). Parenteral nutrition and intravenous antibiotic therapy was given. The patient was discharged on day 9 after surgery and scheduled for elective right hemicolectomy in 2 months’ time.

Case report 2

Adnexal torsion due to a dermoid cyst in the 3^rd trimester of pregnancy

A 35-year-old woman in the 33^rd week of her second pregnancy suffered from diffuse abdominal pain that lasted for 24 hours and later progressed into the right lower abdomen. The pain was accompanied by nausea and occasional vomiting. The patient was known to have Crohn’s disease affecting terminal ileum, in remission at that point, and a solitary gallbladder stone. Gynaecological examination was unremarkable – normal gestation. Blood tests showed elevated inflammatory markers (CRP: 59 mg/l, WBC count: 11×10⁹/l) and signs of peritoneal irritation were present in the right lower quadrant during physical examination. Abdominal ultrasound study was limited due to patient’s late pregnancy and the appendix was not visualized although indirect signs of AA were reported. There were no signs of acute cholecystitis or active inflammatory changes in the terminal ileum. The patient was admitted for typical signs of AA and, because of her advanced pregnancy, Mc Burney’s laparotomy was performed. Surprisingly, a normal appendix was found together with dermoid cyst 5×3 cm in size causing ovarian torsion on the right side (rotated three times around the axis) (Fig. 3). Detorsion of the ovary and resection of the dermoid cyst was performed. Appendectomy was not indicated due to the absence of inflammatory changes. The patient was discharged 5 days after surgery. She vaginally delivered in the 39^th week of gestation. The weight of the newborn was 2100 g. The diagnosis of dermoid cyst was confirmed by histology (Fig. 4).

Case report 3

Spontaneous perforation of an appendiceal mucinous neoplasm

A 66-year-old woman presented with intermittent pain in the hypogastrium. A CT was done showing only a dilated base of the appendix (Fig. 5a, 5b). The scan was reported as postinflammatory changes. The patient refused any further investigations at that point.

One year later, she was admitted for 2-day history of right hypogastrium pain without vomiting, nausea or dysuria. The patient’s surgical history was significant for hysterectomy performed for uterus prolapse with no other comorbidities reported. Blood test showed altered inflammatory markers. Given the suspicion of AA reported by ultrasound scan together with tenderness in the right lower quadrant, diagnostic laparoscopy was indicated. The procedure was converted to open due to unclear findings in the area of appendix. The appendix was found in the medial-dorsal position, with no inflammatory changes, however, dilated at the base and full of mucinous tissue with signs of spontaneous perforation. Standard appendectomy was performed. The patient’s recovery was uneventful and she was discharged on the 7^th postoperative day. The specimen was reported as a low-grade appendiceal mucinous neoplasm (Fig. 6a, 6b). In accordance with oncologists, no further surgical intervention was indicated and patient will proceed with clinical follow-up including a surveillance CT scan in 6 months’ time and a colonoscopy.

Discussion

Differential diagnosis of right lower quadrant pain remains a challenge surgeons frequently face in their clinical practice. The spectrum of organs and potential conditions to be considered is wide and therefore, it is often difficult to reach the right conclusion. Particular case history and physical examination may not raise suspicion of a certain disease. Moreover, ultrasound study or blood test do not always correlate with the clinical findings and do not necessarily reveal the cause of the pain. Three cases were presented in which the only common lead for the surgeon was right iliac fossa pain. Neither ultrasound nor laboratory tests contributed to the right diagnosis.

The treatment of RSD remains controversial and varies from antibiotic therapy only, through prophylactic appendectomy, diverticulectomy, up to radical resection. Despite the controversies, most authors recommend performing a prophylactic appendectomy followed by antibiotic therapy in non-complicated diverticulitis when diagnosed intraoperatively [10,13,21]. The management of RSD depends on the disease stage and should be treated similarly as left-sided diverticulitis [22]. In complicated diverticulitis (stage Ib or higher according to modified Hinchey classification [23]), surgical intervention should be considered [13,21].

For recurrent disease, elective surgical resection should be preferred [13,21]. The early stage of complicated diverticulitis (stage Ib) can be treated conservatively or with CT-guided percutaneous drainage. In Hinchey stage II, CT-guided drainage should be preferred to urgent radical surgery [24]. Laparoscopic peritoneal lavage and drainage (LLD) are also suitable options at this stage. In case of peritonitis (stage III or IV), laparoscopic Hartman’s procedure (LHP) or LLD is indicated according to Liang et al. [25]. In their study, both methods were reported as safe and effective in management of severe diverticulitis. Liang claims that LLD does not treat completely the source of infection, but avoids stoma and has better short- and long-term outcomes than LHP. Gentile et al. [26] published similar results suggesting that LLD is safe and effective, but only for Hinchey stage III. Open Hartmann’s procedure remains the golden standard in the management of stage IV diverticulitis, however, the surgery is associated with a high morbidity and mortality. LLD should be indicated based on individual, complex patient assessment as well as on the department’s experience [27].

In our case, the first attack of diverticulitis was treated with appendectomy followed by antibiotic therapy. The second attack with pericecal abscess was managed by surgery – abscess evacuation and drainage. Given two subsequent episodes of diverticulitis and the fact the second one was classified as complicated, the decision was made to proceed with elective right hemicolectomy.

The incidence of adnexal torsion is approximately 5 per 10 000 spontaneous pregnancies [28,29] and is more frequent in the first and second trimester [15,16]. The onset peaks between 8^th and 16^th week of gestation when uterus grows faster [15], in contrast to the third trimester when the uterus fills out most of the abdominal cavity and the incidence of torsions is rather sporadic.

Dermoid cysts measuring 5 cm and less with benign ultrasound appearance can be treated conservatively during pregnancy [14,30]. Resection should be performed in the cysts larger than 10 cm because of an increased risk of malignancy, rupture or torsion [14,29,30]. The management of cysts 5−10 cm in size remains controversial. Caspi et al. [31] advocate conservative management of adnexal masses with <6 cm in diameter. Masses of 6−10 cm in size require careful evaluation by ultrasound or MRI imaging. If multilocular, thick-walled, semi-solid cysts or cysts with papillary excrescences are detected, resection is recommended [16,29,30]. Some authors claim that if a dermoid cyst larger than 6 cm in diameter is detected by ultrasound or MRI scan in gravidity, elective resection should be performed to prevent surgical emergency [14,16,30].

If elective surgery is indicated during pregnancy, it should be scheduled between the 16^th and 20^th week when the fetus is securely implanted. Moreover, some types of cysts (e.g. functional cysts) can resolve spontaneously by the 16^th week of gestation [14,29]. Patients who underwent surgery due to adnexal torsion or any laparotomy after 23^rd week of gestation are in a significantly higher risk of adverse pregnancy outcomes compared to patients who had the operation in earlier stages of pregnancy [16,30]. This has been also documented in our case report (newborn hypotrophy – 2100 g).

In the first two trimesters, laparoscopy should be preferred, in contrast to the third trimester where open approach is usually indicated due to uterus size. This decision has also been taken in our patient in the 33^rd week of pregnancy. Most current studies have proven that the laparoscopic approach, when compared to open, has similar risks for the fetus. Laparoscopy in pregnancy is considered to be a safe and feasible procedure and the risks of complications are mostly associated with the underlying disease combined with other maternal factors rather than with the type of surgical approach [14,32].

In our case of LAMN, the appendectomy was radical enough because no infiltration of the surrounding colon or mesocolon was present. Nevertheless, careful follow-up is needed including control CT scan after half a year to rule out intraabdominal relapse as well as colonoscopy because the appendiceal neoplasia can be associated with colorectal cancer [17,33]. Patients with mucin limited to the appendix (without any free mucin on the appendix serosa) are at a very low risk of developing PMP and appendectomy is a sufficiently radical procedure. If mucin occurs in the appendix serosa, the risk of PMP has to be considered. Even though, in our case the risk of relapse and PMP had to be considered due to spontaneous perforation, more extended procedure was not indicated from our point of view. The extra-appendiceal mucin was reported by a pathologist as acellular (no neoplastic epithelial cells present). If cellular mucin (with neoplastic epithelial cells) occurred on the appendiceal serosa, the patient would be at a higher risk of developing PMP [18,19,34].

Some authors claim cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) should be considered in patients with a high risk of PMP [18]. More studies focused on the efficacy of CRS and HIPEC should be conducted before these approaches become the method of choice in high-risk patients as they are very difficult to organize and carried out in a limited number of departments; better data about their benefits, effectiveness and significance in the prevention of disease recurrence should therefore be available.

In consensus with oncologists, it has been taken into account that neoplastic epithelial cells had not been detected in the extra-appendiceal mucin and therefore conservative treatment with clinical follow-up was indicated as mentioned previously.

Conclusion

AA usually has a typical clinical course requiring prompt surgery. In this article, three cases are presented where the diagnosis of AA has not been confirmed intraoperatively, nevertheless, in all cases the surgical intervention was indicated. Less common conditions need to be considered in differential diagnosis of right iliac fossa pain. Despite the availability of modern imaging, the indication for surgery should be based on clinical examination and, if any doubts (for example unclear CT or MRI findings), at least a diagnostic laparoscopy should be performed.

Abbreviations:

AA – acute appendicitis

RSD – right-side diverticulitis

LAMN – low-grade appendiceal mucinous neoplasm

PMP – pseudomyxoma peritonei

LLD – laparoscopic peritoneal lavage and drainage

LHP – laparoscopic Hartman’s procedure

CRS – cytoreductive surgery

HIPEC – hyperthermic intraperitonal chemotherapy

CRP – c-reactive protein

WBC – white blood cells

Conflict of Interests

The authors declare that they have not conflict of interest in connection with the emergence of and that the article was not published in any other journal.

Lumir Kunovsky, M.D.

Department of Surgery, University Hospital Brno Bohunice,

Faculty of Medicine MU

Jihlavska 20

625 00 Brno

e-mail: lumir.kunovsky@gmail.com