Low-grade appendiceal mucinous neoplasm

Case contributed by Dr Ammar Ashraf

Presentation

Crampy right lower abdominal pain for one month. No history of change in bowel habits, melena, fever, anorexia, or weight loss.

Patient Data

Age: 60 years
Gender: Male

Small, rounded radiopaque shadow in the right iliac fossa; fecolith in the cecum or appendicolith?

Multiple small phleboliths in the pelvis.

No abnormal bowel dilatation, significant air-fluid levels, or pneumoperitoneum is seen.  

Retrocecal appendix measuring approximately 7 mm in diameter showing no abnormal contrast enhancement. A calcified lesion measuring approximately 11 x 12 mm is seen at its tip. No fat stranding, free fluid, or collection is appreciable around the appendix.  No ascites, pneumoperitoneum, or significant abdominopelvic lymphadenopathy is noted.

Lipomatosis of the ileocecal valve.

Focal renal parenchymal thinning/scarring along the posterior aspect of the upper pole of the right kidney, with mild focal dilatation of the adjacent calyces. Small simple exophytic cortical cyst at the upper pole of the left kidney. 

No other significant abnormality is seen.

Based on these radiographic features, imaging differential diagnosis of a low-grade appendicular malignancy low-grade appendiceal mucinous neoplasm (LAMN),  previously known as appendiceal mucinous cystadenoma}, appendiceal carcinoid, or appendiceal mucocele was given.

Laparoscopic appendectomy: mildly dilated and inflamed appendix, with a calcified soft tissue lesion at its tip.

Case Discussion

Laboratory investigations: Mildly high CRP.  Normal WBC, CEA, CA 19.9, and PSA. 

The patient underwent laparoscopic appendectomy.

Histopathology: Appendiceal mucinous neoplasia, low-grade (LAMN) confined to the muscularis propria, stage Tis (in situ) with calcifications and ossifications in the tip. Presence of acellular mucin dissection in the submucosa. Clear surgical margins.

Peritoneal fluid: Negative for malignant cells. 

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Case information

rID: 77390
Published: 14th May 2020
Last edited: 20th Jan 2021
Tag: lamn
Inclusion in quiz mode: Included
Institution: King Abdulaziz Hospital Al Ahsa (MNGHA)

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