Rare presentation of low-grade appendiceal mucinous neoplasms (LAMN) as an appendicular lump: A case report

The prevalence of appendiceal mucinous neoplasms (AMN) is about 0.2%-0.3% in the specimens of the appendix. The LAMN may appear unremarkable or can present as mucin-filled, crystally dilated tissues. The diagnosis of early-stage AMN is mostly incidental. It is of vital importance to know the features of LAMN for a timely diagnosis.

A 46-year-old male came with the complaint of right iliac fossa swelling along with severe intensity pain and a single episode of vomiting. A 4 × 4cm tender, soft, cystic, mobile swelling was found upon the examination. Contrast-enhanced Computerized tomography (CT) scan of the abdomen revealed the appendix diameter of 10mm well-circumscribed cystic measuring 2.1 × 2 cm. Therefore, an open resection surgery was performed. The histopathological report revealed an intraepithelial lesion composed of flat mucinous epithelial cells having eosinophilic cytoplasm and low-grade nuclear atypia.

The AMNs are very rare neoplasms. The imaging modalities that can be diagnostic methods are abdominal and transvaginal ultrasonography (US), and abdominal computed tomography (CT). The low-grade features of the appendiceal mucinous neoplasms have the possibility of recurrence. The CT-scan findings of appendiceal lump>1.3cm along with cystic dilation and the calcification of the wall are the suggestive features of AMN. There is a high chance of dissemination and port site seeding in case of pneumoperitoneum.

This rare case suggests the significance of adding AMNs as a differential diagnosis in patients with abdominal pain and choosing the right approach to treat such patients to avoid complications.