Mucinous Appendiceal Neoplasia: Case Report and Literature Review

Primary appendececal tumors are rare occurrences, found in lessthan 2% of appendectomies [1]. The mucinous appendix neoplasia accounts for 0.2-0.7% of the cases [2]. Diagnosis is usually performed in the sixth decade of life [3]. Clinical manifestations range from absence of symptoms, acute appendicitis, non-spastic abdominal pain and palpable abdominal tumor [2]. The surgical treatment can be performed appendectomy or hemicolectomy, according to the extent of the lesion [4]. The aim of this study is to report a case of acute appendicitisca used by Low Grade Mucinous Neoplasia (LAMN) and to review histopathological classification and treatment in the literature.

75 years-old, female, hypertensive and diabetic. He was admitted in the Hospital, complaint of pain in the right iliac fossa for 15 days, associated with nausea and hyporexia for 1 day. Denyvomiting, diarrhea and urinary symptoms. Physical examination showed (HR: 88bpm, SatO₂: 98%) semi globous abdomen, abdominal auscultation without alterations, with diffuse pain on right hemiabdomepalpation. Hemogramwith 15,200 leukocytes, 4% of rods.

Ultrasonography of total abdomen performed on the day of care without alterations. Computed tomography showed a distended, thickened appendix with adjacent adipose densification, with no associated perforationor collection signs, suggesting a diagnosis of appendicitis (Figure 1). Anexploratory laparotomy was indicated for possible appendectomy.

Figure 1: Computed Tomography (CT) of sagittal incidence evidencing a distended appendix, thickened with adjacent adipose densification.

During the intra operative period, thececal appendix was observed, blocked by the largeomentum. The appendix was enlarged, hyperemic with thick walls and hyperemiccecum with signs of ischemia, suggesting a neoplastic process (Figure 2). Absence of extra vasation of fecal or mucinous contents in the peritoneal cavity, without lymph node enlargementor peritoneal or hepatic implants. Right colect omy was chosen, with primary anastomosis. Patient progressed uneventfully, being discharged on the 10^thpostoperative day. On the 17th postoperative day, here turned to the hospital with a complaint of surgical wound infection, opted for conservative treatment with antibiotic therapy and wound cleaning.

Figure 2: Aspect of the appendix during the intraoperative.

Histopathological analysis of the surgical specimen presentedcecal appendixw ith 5.0x3.0cm. Presence of low grade, well differentiated appendicular mucinous neoplasia with extension in every organ, with tumor free margin and lymph nodes without involvement (Figure 3).

Figure 3: Histopathological analysis of the appendix, H&E stain. Presented dysplastic epithelium, sometimes venous, sometimes tubular, with a presence of mucin in the cytoplasm of the cell.

The classification of appendix tumors is controversial. Mucin-producing tumors have epithelial origin, according to WHO classification of 2010, mucin-producing neoplasms were divided into 3 groups: Adenomas, LAMN and adenocarcinoma of the apêndix [1].

Currently, by the 2016 Modified Delphi Consensus Protocol the mucinous neoplasms are classified as: LAMN, high grade mucinous neoplasia, mucinous adenocarcinoma with or without signet cell [5].

LAMN and high-grade mucinous neoplasia are lesions restricted to the submucosa and are differentiated by the level of cellular atypia, although these lesions are not malignant, they may present extra appendicular implantation. Mucinous adenocarcinoma is a malignant lesion, whichhas its own muscular invasion [6]. It isbelievedthat LAMN is the initial neoplastic process, with an intermediate stage marked by high grade atypia followed by mucinous adenocarcinoma. The presence of ringcells is indicative of a worse prognosis [7].

The main complicationo f LMNA is the rupture of the appendix causing pseudomyxoma peritonei, a clinical condition characterized by peritoneal neoplastic implantation with accumulation of ascites and fatal outcome [1,2,4,7,8].

LMNA treatment is based on removal of the primary lesions ite by appendectomy [7]. Colectomy is indicated when the tumor is largerthan 2cm in size or involvement of the pericecal región or signs of malignancy [4]. In case of pseudomyxoma peritonei, surgical cytoreduction and hyperthermic intraperitoneal chemotherapy are always indicated [4,7,8].

The LMNA of appendixis a raredisease, usually the diagnosis is made in the intraoperative appendectomy. The histopathological classifications are controversial and the treatment varied, so the surgeon and the pathologist must be attentive to the patient's best conduct and follow-up.

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