pediatric mucinous neoplasm of the appendix presenting as a mucocele a case report and review of the literature

Glicka a Division of Pediatric Surgery, Hofstra Northwell School of Medicine, Steven and Alexandra Cohen Children's Medical Center of New York, Northwell Health, New Hyde Park, NY 11040,

Pediatric mucinous neoplasm of the appendix presenting as a

mucocele: A case report and review of the literature

Barrie S Richa,*, Sudarshana Roychoudhuryb, Alex K Williamsonb, Richard D Glicka

a Division of Pediatric Surgery, Hofstra Northwell School of Medicine, Steven and Alexandra Cohen Children's Medical Center of New York, Northwell Health,

New Hyde Park, NY 11040, USA

b Department of Pathology, Hofstra Northwell School of Medicine, Steven and Alexandra Cohen Children's Medical Center of New York, Northwell Health,

New Hyde Park, NY 11040, USA

a r t i c l e i n f o

Article history:

Received 27 October 2016

Accepted 27 November 2016

Available online 27 November 2016

Keywords:

Mucocele

Mucinous neoplasm of the appendix

LAMN

Pediatric

a b s t r a c t

Mucocele of the appendix is a rare entity in pediatrics, with few case reports in the literature We present

a case of a 17-year-old male with right lower quadrant pain who was found to have an appendiceal mucocele while being evaluated for appendicitis Laparoscopic-assisted resection was performed, with pathology confirming a low-grade mucinous neoplasm of the appendix, a tumor scarcely described in the pediatric population He underwent complete resection with negative margins, rendering him cured without the need for any further resection or treatment We review the literature on this topic

© 2016 The Authors Published by Elsevier Inc This is an open access article under the CC BY-NC-ND

license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

1 Introduction

Laparoscopic appendectomy remains one of the most frequently

performed procedures by pediatric surgeons, with acute

appendi-citis being the most common pathology identified Unexpected

pathologyfindings after appendectomy in children are present in

approximately 2% of specimens, and include pinworm, granulomas,

eosinophilic infiltrates and neoplasms[1] Tumors of the appendix

are rare in the pediatric population, found in less than 0.5% of

pa-thology specimens in this age group, with neuroendocrine tumors

representing the most common tumor-type[1] Mucoceles due to

appendiceal mucinous neoplasms are exceedingly rare in this

population We describe a case of a 17-year-old boy with right

lower quadrant pain found to have a mucocele secondary to a

mucinous neoplasm of the appendix, successfully treated by

lapa-roscopic assisted resection

2 Case report

A 17-year-old boy, with no significant medical history, presented

to the emergency department with one day of abdominal pain The

pain was initially diffuse, and subsequently localized to the right lower quadrant The pain was described as sharp and constant It was associated with emesis, but no fevers, diarrhea, or urinary symptoms The remainder of review of systems was within normal limits He had no family history of malignancy

On physical exam, he was well-appearing and afebrile with normal vital signs His abdomen was soft and tender in the right lower quadrant with localized rebound tenderness His laboratory values were normal, including a white blood cell count of 7.6 K/mL with an Auto Neutrophil % of 53.3% An ultrasound of his abdomen demonstrated a blind-ending tubular structure measuring upwards

of 2.5 cm This structure was seen to extend from the cecum, but did not demonstrate any wall thickening or increased vascularity The luminal contents appeared hypoechoic The impression by the pe-diatric radiologist was appendicitis versus a mucocele of the ap-pendix (Fig 1) Given thesefindings, the patient was taken to the operating room for laparoscopic appendectomy using a standard three-port technique The appendix was easily identified in the right lower quadrant It was significantly dilated and tense (Fig 2a and b) There was no evidence of any freefluid or any mucinous deposits throughout the abdomen and pelvis, including the peri-toneal surfaces In order to better examine the appendix and assure adequate resection, the appendix and cecum were carefully mobi-lized bluntly from their attachments to the right lower quadrant and eviscerated out of the umbilical incision using a wound pro-tector/retractor (Fig 2c)

* Corresponding author Division of Pediatric Surgery, 26901 76th Ave, CH158,

New Hyde Park, NY 11040, USA.

E-mail address: brich@northwell.edu (B.S Rich).

Contents lists available atScienceDirect Journal of Pediatric Surgery Case Reports

j o u r n a l h o me p a g e :w w w j p s c a s e r e p o r t s c o m

http://dx.doi.org/10.1016/j.epsc.2016.11.014

2213-5766/© 2016 The Authors Published by Elsevier Inc This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ).

Journal of Pediatric Surgery Case Reports 17 (2017) 11e14

The appendix was diffuselyfirm to the base of the cecum An appendectomy with partial cecectomy was performed using a 3.5 mm Endo GIA stapler, taking care to resect the specimen at an area of normal cecum (Fig 2d, e, f) There was no violation or spillage of the appendiceal contents and the intact specimen was submitted for intraoperative pathologic consultation The frozen section diagnosis was a low-grade appendiceal mucinous neoplasm (LAMN), and after a multidisciplinary intraoperative discussion, the decision was made to conclude the procedure with appendectomy only

The patient did well post-operatively and was discharged home

on post-operative day 2 Gross pathologic examination revealed a dilated, intact appendix measuring 10 3.5  1.0 cm and cecum measuring 3.5 1.5  0.5 cm (Fig 3a) The appendix mucosa was flat and the lumen was filled with tenacious mucin Microscopic pathologic examination revealed a low-grade appendiceal mucinous neoplasm (LAMN), consisting of flat to villiform mucinous epithelium with basal nuclei and abundant apical cyto-plasmic mucin, without nuclear atypia, evidence of invasion, or

Fig 1 Ultrasound of right lower quadrant showing 2.5 cm appendix with hypoechoic

contents.

Fig 2 a Laparoscopic visualization of mucocele in right lower quadrant, b laparoscopic mobilization of appendix and cecum c extracorporealization of appendix and cecum

B.S Rich et al / Journal of Pediatric Surgery Case Reports 17 (2017) 11e14 12

extra-appendiceal mucin The lamina propria showed somefibrosis

and patchy chronic inflammation, and the distal appendiceal tip

was obliterated by benign spindle cell mesenchymal tissue The

cecal margins and one mesenteric lymph node were negative for

neoplasm (Fig 3b and c)

The patient and his family had significant anxiety after learning

of this rare and surprising diagnosis This was associated with intermittent self-limited vague abdominal pain for several months resulting in a CT scan at 5 months postoperatively This study showed no abnormality He is now 6 months postoperative and doing well

3 Discussion Mucocele of the appendix is a general term referring to a cyst-ically dilated appendixfilled with mucin secondary to non-acute appendiceal obstruction The obstruction can be secondary to an appendicolith, endometriosis, extrinsic compression, in flamma-tion, or neoplasm, and therefore surgical resection and pathologic evaluation are recommended Mucoceles are rarely reported in children, with limited case reports documented Two recent case reports describe children with appendiceal mucoceles that were each resected without any underlying neoplasm, one from a 15 year old girl found to have a thickened appendiceal base during lapa-roscopic appendectomy without any other pathology, and the other from an 11-year old boy with phlegmono-gangrenous appendicitis causing obstruction and subsequent mucocele[2,3]

Mucinous neoplasms of the appendix are a heterogeneous collection of appendiceal epithelial neoplasms that can obstruct the lumen of the appendix while secreting excess mucin, and are thought to cause appendiceal mucocele They are rare lesions, found in approximately 0.2e0.7% of pathology specimens following appendectomy[4,5] They can present mimicking acute appendi-citis with right lower quadrant pain, as an abdominal mass, with an intussusception, or incidentally They are often diagnosed during a work-up for abdominal pain by ultrasound or cross sectional im-aging of the abdomen and pelvis for other indications

Appendiceal mucinous neoplasms are seldom seen in the pe-diatric population, as they typically present in the sixth decade of life[6,7] Alemayehu et al reported the incidence of unexpected pathologyfindings after appendectomy in 3602 children over a 16-year period, and none were found to have a mucinous neoplasm[1] Pai et al described 116 cases of appendiceal mucinous neoplasms over approximately 30 years, and only two patients were under 20 years of age[7] Blecha et al reported a case of a ten-year old boy found to have a mucocele of the appendix with a cystadenoma Similarly to our patient, he presented with right lower quadrant pain Unlike our patient, who was diagnosed by ultrasound, the reported child was diagnosed by computed tomographic (CT) scan, and he also underwent surgical resection with appendectomy and partial cecectomy with a 1 cm margin of cecum[8]

Appendiceal mucinous tumors represent a continuum ranging from benign to malignant neoplasms, with numerous proposed classification schemes and subtypes The WHO classification des-ignates three groupings of mucinous neoplasms including mucinous adenoma, LAMN, and appendiceal adenocarcinoma[9] This categorization was corroborated in a recent international consensus for classification of appendiceal neoplasia, with the addition of high-grade appendiceal mucinous neoplasia[10] Mis-darji and colleaguesfirst described LAMN in 2003 in an effort to clarify an intermediate group of tumors [11] They are typically

defined as lesions confined to the appendix or the local peri-appendiceal tissues without evidence of invasion or disseminated peritoneal disease They are further subclassified based on the de-gree of extra-appendiceal spread The best prognosis is seen with LAMN confined to the appendix without any evidence of extra-appendiceal mucin In one report of localized type, there were no recurrences in 27 patients after resection with a median follow up

of six years [11] Similarly, Pai et al describes 16 patients with LAMN confined to the appendix without any post-operative

Fig 3 a Gross image of fixed and opened specimen showing smooth, tan appendiceal

lumen and brown cecal orifice at left b Low-power histologic image of appendix

showing flat to villiform mucosa with mucinous epithelium c High-power histologic

image of appendix showing epithelium with apical mucin, basal nuclei, and

confine-ment to the mucosa, as well as fibrosis and inflammation in the lamina propria.

B.S Rich et al / Journal of Pediatric Surgery Case Reports 17 (2017) 11e14 13

recurrences with a mean follow up of 5.25 years [7] Mucin is

divided into cellular and acellular depending on whether it

con-tains or lacks neoplastic cells, respectively LAMN with acellular

mucin in the right lower quadrant manifests a low risk of

recur-rence or progression to pseudomyxoma peritonei (PMP),

approxi-mately 4e8%[7,12], whereas LAMN with cellular mucin in the right

lower quadrant demonstrates a higher risk of recurring as

disseminated disease, as high as 33e75%[7,11]

Surgical resection is the mainstay of treatment for LAMN When

LAMN is confined to the appendix, complete resection by

appen-dectomy with a negative proximal margin is sufficient for cure If a

large base of the appendix is found, a cecal resection may be

necessary to assure a negative margin for the appendiceal stump If

neoplastic epithelium involves the proximal resection margin,

some authors recommend further resection with cecectomy[7] In

contradistinction, Arnason et al report that LAMN confined to the

appendix with involvement of the appendectomy margin by either

neoplastic epithelium or acellular mucin does not predict

recur-rence of disease without further resection Furthermore, there was

no evidence of neoplasia in any of the re-resected specimens These

authors recommend a more conservative approach with

colonos-copy and radiographic studies for surveillance in the setting of a

positive margin [13] In cases with extra-appendiceal spread,

complete resection of the appendix is necessary along with

resec-tion of any grossly involved surrounding periappendiceal tissue or

implants Cytologic examination of any mucin or ascites in the

peritoneal cavity is obligatory Right hemicolectomy is only

indi-cated for invasive adenocarcinomas without peritoneal disease

[14] Cytoreductive surgery with intraperitoneal chemotherapy is

recommended for disseminated peritoneal disease[15,16]

The use of laparoscopy for LAMN has been reported to be both

safe and feasible provided the appendix is cautiously handled and

dissected without violation or rupture and subsequent dispersion

of mucin[17,18] This is critical as rupture of these tumors can lead

to peritoneal seeding of mucin-producing epithelial cells, or PMP,

and portends a poorer prognosis[7] Misdrahi et al affirms this

increase in mortality with a 45% 10-year survival rate of patients

with LAMN with extra-appendiceal spread[11] Laparoscopy also

allows for careful and complete examination of the peritoneal

surfaces of the abdomen and pelvis to rule out dissemination Our

patient successfully underwent laparoscopic dissection with

extracorporeal resection through a limited umbilical incision with a

wound protector/retractor This technique utilized careful

laparo-scopic tissue handling without rupture or gross spillage of the

ap-pendix, while simultaneously allowing for tactile assistance to

assure negative gross margins This was completed without the

need for an enlarged incision or any subsequent surgical resection

Pathologic examination of our patient's specimen verified a LAMN

confined to the mucosa and a negative cecal margin, corroborating

complete resection and cure

There is no standard recommendation for surveillance of LAMN

after resection, especially in a pediatric patient who would

neces-sitate long-term observation In patients subclassified as low-risk

LAMN, McDonald et al recommended a watch-and-wait policy

with surveillance imaging at 6 months, then annually The authors

promote long-term surveillance and follow-up with a specialist

service[19] For ruptured neoplasms, Murphy et al recommends

baseline tumor markers and a CT scans every year for 5 years, then

every 2 years for 10 years to monitor for any long term recurrence

[20] Our patient has already had cross-sectional imaging at 5

months post-operatively

4 Conclusion Appendiceal mucinous neoplasms are rare tumors in the pedi-atric population but should be considered when a mucocele is identified pre-operatively or intra-operatively LAMN is a low-grade neoplasm treated by complete surgical resection when confined to the appendix A laparoscopic-assisted approach with careful handling to prevent rupture is advocated, and an extracor-poreal resection may assist in assuring negative margins and sub-sequent cure Further studies are needed to assess the long-term surveillance and follow-up necessary for pediatric patients with LAMN

References

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[2] Arrington D, Jewett B, Sterner S, Caplan M, Thacker P Incidental mucocele of the appendix in a 15-year-old girl Pediatr Emerg Care 2014;30(8):555e7 [3] Balint IB, Nad M, Kiraly A, Bali O, Rashed A, Vizsy L Giant appendix or an appendiceal mucocele? Case report of an 11-year-old child Interv Med Appl Sci 2014;6(4):187e90

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[7] Pai RK, Beck AH, Norton JA, Longacre TA Appendiceal mucinous neoplasms clinicopathologic study of 116 cases with analysis of factors predicting recurrence Am J Surg Pathol 2009;33(10):1425e39

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