Introduction

Symptomatic isolated submucosal intestinal lipomatosis is a rare entity [1,2]. Lipomatosis is characterized by an increased infiltration of well-differentiated fat within the submucosal layer of the bowel. Unlike lipomas, lipomatosis lacks a defining capsule [3]. It is commonly observed in the cecum, ascending colon, sigmoid colon, transverse colon, rectum, and descending colon with decreasing frequency [3]. The presence of lipomatosis in the appendix is quite rare. The exact etiology of this condition remains unknown.

Case Report

A 72-year-old female presented to the emergency department with symptoms indicative of an acute abdomen. She was conscious, coherent, and cooperative, with stable vital signs. Physical examination revealed tenderness in the right iliac fossa. Suspecting acute appendicitis, a computed tomography (CT) scan was performed for further evaluation. The computed tomography (CT) scan of the abdomen and pelvis revealed the appendix in a pelvic position, exhibiting a uniformly hypodense thickened wall.

The maximum wall-to-wall diameter measures approximately 89 mm, with the submucosa showing fat density ranging from -30 to -90 HU. No other signs of inflammation like peri appendiceal fat stranding, fluid accumulation, or lymphadenopathy were noted. A diagnosis of isolated submucosal lipomatosis of the appendix was made. Consequently, the patient was discharged the following day after her symptoms had resolved.

Figure 1: Non-contrast Enhanced Computed Tomography Axial plane

The pathogenesis of appendiceal lipomatosis remains unclear, with potential etiological factors including embryonic displacement of adipose tissue, degenerative changes affecting fat metabolism, post-chemotherapy fat deposition, chronic irritation, low-grade infection, and hamartomata’s syndromes [4].

Lipomatosis can present with a range of non-specific symptoms, including abdominal pain, diarrhoea, constipation, sub ileus or ileus, and bleeding. In some cases, it may manifest as acute appendicitis. The presumed cause is a mechanical obstruction of stool discharge from the appendix due to lipomatosis [5].

On radiological imaging techniques, thickening of the appendiceal wall which is in favour of fatty tissue without peri appendiceal inflammation, fluid accumulation, or lymphadenopathy is suspicious for the diagnosis. Hypodense homogeneous thickening between -80 to -120 HU on CT, high intensity in T1 and T2 weighted sequences on MRI and decreasing intensity in fat suppression sequence support fatty tissue infiltration. Despite its rarity, appendiceal lipomatosis should be considered in the differential diagnosis of acute appendicitis when clinical findings are uncertain.

Conclusion

Gastrointestinal lipomatosis is a rare occurrence, with isolated submucosal lipomatosis being exceptionally uncommon. Symptoms are only present in a small number of patients. Physicians need to be mindful of this condition to avoid unnecessary surgical procedures, especially when both clinical and laboratory results appear stable.

Despite their rarity, this condition should be considered in the differential diagnosis of suspected cases of acute appendicitis where clinical uncertainty exists, a CT scan is a reliable diagnostic tool. A definitive diagnosis necessitates a histopathological examination.

References