Leiomyoma of the gastric wall

Clinical History

A 64-year-old patient with a three-month history of pyrosis was referred for post-prandial feeling of fullness and intolerance to meat-containing food. He was investigated with upper gastrointestinal tract endoscopy and a gastric lesion was found.

Imaging Findings

Upper gastrointestinal tract endoscopy revealed a fundal mass of about 6 cm in diameter, bleeding and completely covered by fibrinous exudate (Fig. 1).
Biopsies were not performed into the lesion surface because of the high risk of bleeding.
Abdominal computed tomography (CT) showed a mass arising from the posterior wall of the stomach with significant and homogeneous contrast enhancement (diameters 16x21x12 mm) (Fig. 2-3).
Patient underwent laparotomy with wide excision of the mass.
Anatomo-pathological analysis of the surgical specimen resulted in leiomyoma of the gastric wall. Immunohistochemical analysis was: desmin+, smooth muscle actin+, CD117-, CD34-, S-100-, vimentin- (Fig. 4).
Gastric resection margin and sixteen lymph nodes removed resulted normal.

Discussion

Gastric leiomyomas (GLMs) is a rare neoplasm (2.5% of gastric tumours), but the most common gastric benign smooth-muscle tumour (80%); it is composed of connective tissue and smooth-muscle elements which commonly originate from circular and longitudinal muscolar layers, rarely from the muscolaris mucosae.
GLMs most frequently develop in the lower half of the stomach but they might also be found in the fundus; with few exceptions, GLMs are solitary, with regular borders and small dimension (<5cm).
Ulceration of the mucosa overlying the tumour is reported in 50-70% of tumours larger than 2 cm in diameter; endophitic growth is the commonest presentation, even if exophitic GLMs have been reported.
GLMs are usually asymptomatic and occasionally found during investigations for other reason or at autopsy. If symptomatic, meat-meal intolerance, dysphagia and upper abdominal discomfort after meals frequently occur and depend on lesion size and localisation. Upper gastrointestinal bleeding due to mucosal ulceration or pain behind the sternum might be referred.
Double-contrast barium X-ray is required to investigate dyspepsia: endophitic GLMs appear as a filling-defect on gastric walls; ulceration over lesion surface might be demonstrated as barium accumulation over the mass.
Endoscopy is useful to directly see the lesion and to effectuate biopsy; however, exophitic leiomyomas simulating extrinsic tumours are not well demonstrated by barium study or endoscopy, since these techniques are not able to indicate exactly tumour extension outside the gastrointestinal tract.
Endoscopic US (EUS) examination allows to establish exactly gastric walls involvement (mucosal, submucosal and muscolaris).
At CT evaluation, GLMs are depicted as well-delineated rounded or oval masses of variable size, with homogeneous attenuation (equivalent to muscle) and moderate contrast enhancement after contrast administration. Occasionally focal calcification within the mass might be appreciated.
Final diagnosis is based on biopsy: at histological examination GLMs contain characteristic muscular fibres in a whorling pattern which distiguish them from normal muscle [1].
According to nuclear aspect and cellularity, GLMs might be classified in bizarre leiomyomas or leiomyoblastomas if extreme hyperchromatic nuclei are demonstrated; furthermore, in case of nuclei similar to epitheliod cells, GLMs are classified as epitheliod leiomyoma.
Negativity of molecular markers as cKIT, CD34, Vimentina and S-100 allows differential diagnosis from GIST (95% positive cKIT and 70% positive CD34) and from gastric lymphoma, carcinoma or submucosal lipoma [2].
Since mitotic activity might vary in different portions of the tumour, it is hard to distinguish leiomyoma from leiomyosarcoma; therefore tumoral malignancy depends mainly on tumour clinical behaviour, tumoral size and grade of infiltration, as well as node involved and metastasis.
Furthermore, since differentiation between leiomyoma and leiomyosarcoma on gross examination is challenging, surgical resection is mandatory.
Laparoscopy resection is the treatment of choice, even if endoscopic resection aided by intraoperative endoscopic ultrasound has been demonstrated as safe technique; a combination of both techniques has resulted to be successful and safe [3].
Robotic-assisted laparoscopic wedge resection with intraoperative ultrasound localisation might be used too [4].
Imaging techniques (in particular CT evaluation) are required to understand lesion precise location and extension, having a fundamental role in follow-up, especially in order to exclude anastomosis dehiscence.

Differential Diagnosis List

Final Diagnosis

Gastric leiomyoma

URL:	https://www.eurorad.org/case/8966
DOI:	10.1594/EURORAD/CASE.8966
ISSN:	1563-4086