Gastric lipoma is a benign mesenchymal tumor originating from the submucosal layer of the gastric wall. It constitutes 1-3% of all gastric tumors and is the third most common benign gastric tumor (after GIST and leiomyoma). Usually located in the antrum region (75%). Most are asymptomatic and incidentally detected; large lesions (>4 cm) may present with obstruction, intussusception, and GI bleeding from ulceration. The pathognomonic finding on CT is a submucosal, homogeneous, well-defined, fat-density (-40 to -120 HU) mass — this density is not seen in any other submucosal tumor and is diagnostic. High signal on T1 MRI and signal loss on fat suppression confirm the diagnosis. The 'pillow sign' on endoscopy — probe indenting into soft tissue when pressed with forceps — is characteristic. Treatment is needed only in symptomatic cases.
Age Range
40-75
Peak Age
60
Gender
Female predominant
Prevalence
Rare
Gastric lipoma results from focal proliferation of adipocytes in the submucosal loose connective tissue. It consists of mature fat tissue surrounded by a thin fibrous capsule — no malignancy potential. Slow tumor growth reflects low mitotic activity and benign biology. Submucosal location indicates the tumor originates from the third layer (submucosa) of the gastric wall — mucosa is stretched over the tumor and may ulcerate in large lesions (ischemic necrosis — mechanical compression of the tumor disrupts mucosal blood flow). The pathognomonic fat density on CT directly reflects the tumor consisting of mature adipose tissue — long carbon chains in triglycerides and low electron density produce negative HU values. Homogeneous density indicates uniform fat composition of the tumor — no heterogeneity seen in sarcoma or other malignant tumors. The 'pillow sign' reflects the soft, compressible nature of the tumor — mature fat tissue easily deforms under mechanical pressure.
Submucosal, homogeneous, well-defined, fat-density (-40 to -120 HU) mass in the gastric wall = gastric lipoma. This density is not seen in any other gastric submucosal tumor and is pathognomonic. No biopsy needed; CT diagnosis is sufficient.
On non-contrast CT, gastric lipoma appears as a homogeneous, well-defined, smooth-contoured, fat-density (-40 to -120 HU) mass in the submucosal layer of the gastric wall. Density is identical to subcutaneous fat — this pathognomonic finding is not seen in any other submucosal gastric tumor. A thin capsule surrounds the lesion. No internal septation, calcification, or solid component (unlike liposarcoma). Erosions may be seen in the overlying mucosa of large lesions (>4 cm).
Report Sentence
A submucosal, homogeneous fat-density (-___ HU), well-defined mass measuring approximately ___ × ___ cm is seen in the gastric antrum region; consistent with gastric lipoma.
In the arterial phase, gastric lipoma shows no enhancement — fat density remains unchanged. This reflects the avascular nature of mature adipose tissue. The thin capsule may show minimal enhancement. If mucosal ulceration is present, increased mucosal enhancement may be seen at the ulcer base. Absence of enhancement is an important finding for distinguishing lipoma from GIST (enhancing) and leiomyoma (enhancing).
Report Sentence
On contrast-enhanced series, the submucosal mass shows no enhancement with unchanged fat density; findings consistent with benign lipoma.
On T1-weighted MR images, gastric lipoma shows high signal (bright) — isointense to subcutaneous fat. Shows marked signal loss on fat-suppressed sequences (STIR, fat-sat) — this finding confirms fat content and is diagnostic. On T2-weighted images, intermediate-to-high hyperintense signal is observed. Chemical shift artifact (signal loss at fat-water interface) may be seen at lesion margins. MRI is particularly useful in equivocal CT cases (small lesion, partial volume effect) and patients where radiation exposure should be avoided.
Report Sentence
On MRI, the submucosal mass shows high signal on T1 with marked signal loss on fat-suppressed sequence; consistent with mature fat tissue confirming the diagnosis of gastric lipoma.
On endoscopic ultrasound (EUS), gastric lipoma appears as a well-defined, hyperechoic, homogeneous mass in the submucosal layer (3rd layer). Muscularis propria (4th layer) is intact and the lesion does not invade this layer. No posterior acoustic shadowing. Hyperechoic appearance reflects the different acoustic impedance of fat tissue from surrounding submucosal loose connective tissue. EUS wall layer analysis confirms the submucosal origin of lipoma and distinguishes from GIST (4th layer, hypoechoic).
Report Sentence
On EUS, a hyperechoic, well-defined, ___ mm mass originating from the 3rd layer (submucosa) is seen in the gastric antrum; 4th layer (muscularis propria) is intact; consistent with lipoma.
Large gastric lipomas (>4 cm) may rarely cause intussusception — gastrogastric or gastroduodenal intussusception. On CT, telescoped gastric wall layers with a fat-density lead point mass at the apex of the intussusceptum are seen. Obstruction findings (gastric distension, fluid) may accompany. This complication is a surgical indication.
Report Sentence
Gastroduodenal intussusception with a fat-density lead point mass in the gastric antrum is seen; consistent with lipoma-induced intussusception.
Criteria
Small (<4 cm), asymptomatic, incidentally detected. Most common type (80%).
Distinct Features
No follow-up or treatment needed. Pathognomonic fat density on CT is diagnostic.
Criteria
Large (>4 cm), symptomatic with obstruction, bleeding, or intussusception.
Distinct Features
Requires surgical or endoscopic resection. GI bleeding risk from ulceration. Intussusception is emergency surgical indication.
Criteria
Lipoma with ulceration in overlying mucosa. May present with GI bleeding.
Distinct Features
Fat-density mass + overlying mucosal defect on CT. May be active bleeding source. Endoscopic or surgical resection.
Distinguishing Feature
GIST soft tissue density (30-50 HU), enhances; lipoma fat density (-40 to -120 HU), no enhancement. GIST from 4th layer, lipoma from 3rd layer.
Distinguishing Feature
Leiomyoma soft tissue density, homogeneously enhancing; lipoma fat density, non-enhancing. Both submucosal but density dramatically different.
Distinguishing Feature
Liposarcoma heterogeneous, contains non-adipose solid components, septation, enhancement; lipoma homogeneous fat, no enhancement. Liposarcoma extremely rare in stomach.
Distinguishing Feature
Schwannoma soft tissue density, homogeneously enhancing; lipoma fat density. Schwannoma S-100 positive.
Urgency
routineManagement
conservativeBiopsy
Not NeededFollow-up
no-follow-upGastric lipoma is a benign tumor and the pathognomonic fat density on CT is diagnostic without biopsy. No treatment or follow-up is needed for asymptomatic lipomas. In symptomatic cases (obstruction, bleeding, intussusception), endoscopic polypectomy (for small lesions) or surgical resection is performed. No malignant transformation risk.
Gastric lipoma is a benign lesion and definitive diagnosis can be made with typical imaging findings. If symptomatic (bleeding, obstruction), endoscopic or surgical resection is performed. Asymptomatic cases require follow-up only.