Lipomas are benign soft tissue tumors that are composed of mature lipocytes and circumscribed by a fibrous capsule. Macroscopically, lipomas are formed by yellowish fat tissue of various sizes [4, 5]. Even though the etiology remains unknown, studies suggest that lipomas might be related to an embryological sequester of adipocytes or even be due to the natural process of aging [4, 5].
In 1955, Weinberg and Feldman  reported 135 cases of lipoma in the gastrointestinal tract through a meta-analysis of 60,000 autopsies . In 1963, a study of 4000 surgical resections of benign tumors of the gastrointestinal tract by Mayo et al. revealed that the incidence of lipoma was about 4%, which was distributed as follows: the esophagus (1.6%), followed by the stomach (3.2%), duodenum/small intestine (31.2%), and, most frequently, the colon (64%) .
Gastric lipomas prevail between the fifth and seventh decades of life, are found mainly in women, and usually are small and asymptomatic and are detected incidentally [3, 4, 10]. They are rarely large, intramuscular, or poorly circumscribed but rather are usually smooth, mobile, and painless masses [1, 4, 5, 10]. Turkington , in 1965, reviewed 157 cases in the literature and demonstrated that lipomas may arise from every part of the stomach but less frequently from the cardia and pylorus.
The occurrence of symptoms depends on the size and location of the tumor. Lesions of less than 2.0cm are usually asymptomatic. In patients with larger lesions, the most common symptoms are hemorrhage, abdominal pain, pyloric obstruction, and dyspepsia. Additional symptoms may include diarrhea, constipation, and intussusception [1, 4, 10, 11]. Gastrointestinal bleeding is typically chronic and minimal and is able to cause anemia . Thus, it is noteworthy that, in spite of the volume and extension of the mass, our patient was oligosymptomatic, presented no bleeding or anemia, and reported only upper abdominal discomfort and fullness.
Lately, new imaging techniques such as conventional endoscopy and endoscopic sonography have become important tools for investigating gastric lipomas. Conventional endoscopy reveals lipomas as smooth, oval or round, yellowish, solitary, protruding masses that are covered by mucosa and that may present ulcerated areas. Classic endoscopic features are highly suggestive, such as the “tenting sign” (overlying mucosa may be observed), the “cushion sign” (the smooth consistency of the lesion may be flattened and restored), and the “naked fat sign” (fat extrusion is detected after biopsy) [4, 10–13].
Biopsy through conventional endoscopy reveals only a typical mucosa and thus is not able to confirm diagnostic suspicions [12, 13]. In the case described, only conventional endoscopy was available. Therefore, the biopsy fragments from the ulcers could not securely indicate whether the underlying submucosal mass was benign, an indication that could have led to a less aggressive treatment choice. Recent literature points out the possibility of performing methods other than the lift-and-cut biopsy technique for submucosal sampling, such as echo-guided punction and diathermal loop biopsy .
The use of endoscopic sonography is useful for identifying the tumor’s primary layer, which is best for describing the lesion’s morphology, and reveals possible invasion of the lymph nodes and peripheral layers. Typically, lipomas are visualized as hyperechoic homogeneous lesions that have regular margins and that arise from the third layer [12–14]. The isolated use of such technology has a low accuracy in diagnosing subepithelial lesions and must be complemented by endoluminal resection technologies for histological confirmation . Because endoscopic sonography was not available for resolving the reported case, the primary suggested diagnosis was a possible malignant tumor.
The best noninvasive exam for large gastrointestinal lipomas is abdominal computed tomography, which is sufficient yet not definitive for diagnosis . Imaging findings include a well-delimited homogeneous gastric mass with a density of between −70 and −120 Hounsfield units. Other characteristics are ulceration of the mucosa correlated with the presence of a fibrovascular septum and linear margin with soft tissue density. Such aspects exclude the malignant hypothesis of liposarcoma, thus discarding the need for a biopsy [5, 10, 11]. In this case, because computed tomography was inconclusive and the biopsies from the conventional endoscopy were unhelpful, the hypothesis of malignancy could not be excluded. Therefore, the team decided to perform a gastrectomy, which would be unnecessary in other circumstances.
Incidental lipomas should not be treated, as there are no reports of malignant degeneration [1, 12, 13]. Lesions of less than 6.0cm in diameter or with endoluminal or extraluminal protrusion should undergo laparoscopic resection [11, 13]. Surgical excision is indicated because of symptoms, imminent life-threatening risk, and the impossibility of excluding malignancy [11–13]. Endoscopic resection has become important since frequent uneventful surgical and post-operative reports were published [3, 13]. The most important differential diagnosis for gastric lipoma aside from liposarcoma is a gastrointestinal tract soft tissue tumor such as a gastrointestinal stromal tumor, leiomyoma, fibroma, and their malignant variables. Occasionally, gastric lipomas may also have to be distinguished from other types of intramural tumors, such as the neurilemoma, adenomyoma, Brunner’s gland adenoma, and heterotopic pancreas .