A 73-year-old man presented to a local hospital with chest pain and pleural effusion.
Thoracentesis revealed a hemorrhagic exudate without malignant cells. Computed tomography
showed a mass 5×5 cm in size at the left diaphragm, extending into the peritoneal
cavity adjacent to the stomach. On gastroscopy, a large mass was detected in the gastric
fundus, with intact overlying mucosa (Figure [1]). The patient was referred to our institution for further work-up. Endoscopic ultrasonography
(EUS) using a curved-array echo endoscope (Pentax FG-34UX) revealed a lobulated hypoechoic
mass compressing the intact gastric wall (Figure [2]). The precise cranial extent of the mass could not be defined. There were no enlarged
perigastric or celiac lymph nodes. EUS-guided transgastric fine-needle aspiration
(FNA) was performed, and cytological examination of the aspirate showed numerous clusters
of large atypical mesothelioma cells. The diagnosis was confirmed by positive immunohistochemistry
staining for keratin (Figure [3]) and negative staining for HEA 125. The patient was deemed to be inoperable; the
tumor progressed despite palliative chemotherapy, and he died six months later.
Figure 1The endoscopic image showing an extrinsic mass compressing the gastric fundus. The
overlying gastric mucosa appears intact
Figure 2Endosonographic image of the lobulated hypoechoic lesion (T) adjacent to the gastric
fundus
Figure 3Fine-needle aspirate, with numerous clusters of large mesothelioma cells with a low
nucleocytoplasmic ratio, anisonucleosis, and occasional prominent nucleoli. The mesothelioma
cells show a typical staining pattern, with strongly positive staining for keratin
(mAb KL1) (left) and calretinin (right) (DAB, original magnification × 400)
Endosonography is a well-established method for distinguishing between submucosal
gastric tumors and extraluminal compression [1]. Transgastric FNA allows accurate tissue diagnosis in most cases of extraluminal
masses, with somewhat lower accuracy rates reported for submucosal masses [2]. Large EUS series for patients with “submucosal” gastric tumors have not reported
mesotheliomas in the differential diagnosis [1]
[3]
. As was the case in the patient reported here, intra-abdominal growth of pleural
mesotheliomas may occur, and this represents an advanced stage of disease (T4). EUS-guided
FNA provides a low-risk approach for diagnosing such lesions.
