A 75-year-old man was referred to our hospital for the evaluation of dysphagia for 9 months.
He had associated symptoms of nausea and vomiting but denied hematemesis, hematochezia, lethargy, and dyspnea.
He was an active smoker and consumed alcohol for 30 years.
Physical examination revealed no peripheral lymphadenopathy, thyromegaly, ascites, or mass in the abdomen.
Laboratory data were normal: HBs-Ag negative, HIV negative, and syphilis negative.
Test for serum antibody against Helicobacter pylori was negative.
Chest computed tomography (CT) was notable for a huge well-circumscribed and homogeneous cylindrical mesenchymal neoplasm measuring 15.5×5.9×4.0 cm in lower and middle esophagus with mild contrast enhancement (Fig.1A).
CT revealed no abnormalities in the lungs, heart, ribs, or mediastinum.
Endoscopic examination showed a submucosal lesion in the esophagus starting at 20 cm from the incisor teeth extending up to the cardia (Fig.1B).
Endoscopic ultrasonography (EUS) revealed hypoechoic lesion with a clear boundary located in the 4th layer.
The mass appeared as a benign tumor and was preoperatively diagnosed as esophageal leiomyoma based on chest CT, endoscopic examination, and EUS findings.
Endoscopic mucosal resection or endoscopic submucosal resection was not possible because of large size.
Hence, surgical resection was planned and informed written consent was taken.
The patient underwent thoracoscopic-assisted resection of the mass with gastroesophageal anastomosis, thoracic duct ligation, and jejunostomy.
Postoperative course was uneventful.
Grossly, a spindle shaped lump measuring 14 × 3.5 × 2.5 cm, was observed in the resected esophagus, which grew into the esophageal lumen and blocked most of lumen.
This lump located in the submucosa was covered with intact mucosa, without erosion, ulcer, and hemorrhage.
Its cut surface was homogenously white to grayish-white in color.
Histological examination using hematoxylin and eosin staining revealed that tumor was covered with intact squamous epithelium, arising from the submucosal layer and expanding in to the muscular layer.
The tumor was composed of many nodules of varying sizes separated by collagen fibers.
Numerous cytoplasm-rich cells were observed in the collagenous septations with invasive growth pattern (Fig.2A–C).
The nodules were mainly composed of small to mid-sized centrocyte-like or monocyte-like cells arranged in diffuse pattern.
These atypical lymphocytes possessed clear boundary, pale cytoplasm, irregular nucleus, and occasional nucleolus (Fig.2D).
Mitosis was rare.
No lymphoepithelial lesion was recognized in the lesion.
On immunohistochemical staining, epithelium was diffusely positive for cytokeratin (Fig.3A), and the tumor cells were diffusely positive for cluster of differentiation (CD)20, paired box 5 (Fig.3B), and B-cell lymphoma (Bcl)-2 (Fig.3D).
Small deposits of tumor cells, which were distributed mainly in the collagen fibers, were positive for multiple myeloma oncogene 1, CD138, and CD43.
Several tumor cells were also positive for CD30.
Small lymphocytes were positive for CD3 and CD5.
Follicular dendritic cells were positive for CD21 and CD23 (Fig.3C).
All cells were negative for CyclinD1, CD10, Bcl-6, and B lymphocyte specific activation of OCT binding protein 1.
These follicular dendritic cells were arranged in nodules in which the tumor cells were relatively evenly distributed.
This pattern was suggestive of follicular colonizations seen in MALT lymphoma.
In this case, gene rearragements and clonality analysis of immunoglobulin heavy chain gene, kappa light chain gene, and lambda light chain gene was performed using the IdentiCloneTM IGH/IGK/IGL Gene Clonality Assay (InVivoScribe Technologies, CA).
On monoclonal gene rearrangement, 1 band appeared within 150 to 175 base pairs (bp) in heavy chain gene, 2 discrete bands within 225 to 250 bp in kappa light chain gene, and 1 band within 125 to 150 bp in lambda light chain gene (Fig.4).
In addition, no Epstein–Barr virus was observed in this lymphoma on in situ hybridization using the EB virus-encoded small RNA (Fig.3E, F).
Based on the clinical data, pathological, immunohistochemical, and gene rearragements analysis, final diagnosis of primary esophageal MALT lymphoma was made.
After the surgical resection, no additional therapy in the form of chemotherapy or radiotherapy was administered.
Over the 8 months of follow-up, no evidence of recurrence or metastases was found on CT and the patient has been asymptomatic.
Ethical approval for this study was obtained from Medical Ethics Committee of the Third Affiliated Hospital, the Third Military Medical University.
Written informed consent was obtained from the patient for the publication of this case report and the accompanying images.