Gastric mucosa-associated lymphoid tissue: The need for prompt histologic diagnosis

Gastric mucosa-associated lymphoid tissue has a well established pathophysiologic link with Helicobacter pylori infection. Mucosa-associated lymphoid tissue (MALT) is acquired through chronic inflammation/antigenic stimulation in organs which are normally devoid of lymphoid tissue. We report a case of a 65 years old man with a two year history of dyspeptic symptoms associated with gradual weight loss and an epigastric mass. With poor response to anti-ulcer regimens in a peripheral hospital, he was offered a gastrectomy. The histologic report of the mass showed atypical lymphoid cells infiltration of the gastric mucosa up to the muscularis propria. He was promptly commenced on a standard chemotherapeutic regimen for Non Hodgkin’s lymphoma, but demised before the second course of chemotherapy. This case highlights the need for prompt endoscopy with biopsy and histologic diagnosis of specimen to shorten delays in diagnosis and improve outcome of patients with gastric mucosa-associated lymphoid tissue.

Keywords: Gastritis, Helicobacter pylori, Mucosa-associated Lymphoid Tissue

Gastric MALT lymphoma is a low-grade extranodal B-cell tumor which is caused by Helicobacter pylori infection. This malignancy may occur in patients with vague symptoms of dyspepsia (such as you have in peptic ulcer disease) and some studies in our environment have shown that 75 to 95% of patients with dyspepsia have H. pylori infection of the gastric mucosa. Thus, H. pylori infection is regarded as a public health concern. Antibiotic eradication of this organism from the stomach can prevent this fatal sequel of H. pylori infection or cause regression of the tumor in the early stages. Thus, endoscopic evaluation plays a major role in early diagnosis and staging of this disease. We report one of such cases which was managed blindly as a case of peptic ulcer disease in a peripheral health center and valuable time was lost in his management.

A 65-year-old diabetic patient was referred to the Haematology Out-patients’ Clinic of University of Port Harcourt Teaching Hospital (UPTH) with complaints of fever, weakness, and right neck swelling. He gave a 2-year history of dyspeptic symptoms, 1 year of gradual unintentional weight loss, and 1-month history of swelling in the neck. He used to have epigastric pains which worsened by feeding and a bit milder when he had not eaten. About 1 year prior to presentation, he noticed that he had a small swelling in the epigastrium. There was also a feeling of a dragging movement in his stomach associated with the pains, no history of melena stools however. He had a partial gastrectomy in the same Private clinic 9 months before presenting to our center.

A histological examination of the polypoid mass resected from the stomach was done and it was found that the covering gastric mucosa was infiltrated by atypical lymphoid cells which extended to the muscularis propria. A diagnosis of MALT was made.

On examination at UPTH, he was chronically ill looking, with mild weight loss, he was neither pale nor in obvious painful distress. He had significant lymphadenopathy in the cervical, axillary, epitrochlear, and inguinal regions; the smallest being 3 cm and the largest about 6 cm. They were rubbery in consistency and some were matted together. The spleen was 4 cm below the left coastal margins and liver span was 14 cm. Other systemic examinations were essentially normal.

Abdominal USS showed matted enlarged pre-aortic and para-aortic lymph nodes with widening of the aortomesenteric angle. There were no paravertebral masses. A diagnosis of Disseminated Gastric MALT Lymphoma Stage IV _E (Ann Arbor – Musshoff modification) was made.

Management consisted of initial commencement of H. pylori eradication treatment with antibiotics and proton pump inhibitors and then followed with specific chemotherapy using the cyclophosphamide, vincristine, and prednisolone combination. Patient however died before the second cycle.

The gastrointestinal tract is the most common site where MALT lymphoma occurs, but it can also be found in the thyroid, orbit, salivary glands, etc. ^[1] Studies in Nigeria have shown that up to 75 to 95% of patients with dyspepsia have H. pylori infection of the gastric mucosa. ^[2],[3] The prevalence of H. pylori infection worldwide is approximately 50%; as high as 80 to 90% in developing countries. ^[4] H. pylori is responsible for 63% of stomach cancer worldwide and increases risk by between 5- and 6-fold. 5.6% of the global cancer is caused by H. pylori.^[5]

Many of the people infected may remain asymptomatic for a long time or may have vague symptoms similar to PUD, as in the index patient. Symptoms such as abdominal pain and vomiting are more likely to be associated with MALT lymphomas than with secondary nodal lymphoma. ^[6] Other symptoms indicating more advanced disease overlap with those of gastric carcinoma, including anemia, weight loss, and gastrointestinal bleeding. When patients present with such symptoms as these, physicians should consider the possibility of a gastric MALT lymphoma and offer them diagnostic endoscopy, biopsy, and histology.

There are different staging systems of gastric MALT, all the systems aim at describing the extent of infiltration of the malignant lymphoid cells into the stomach wall, surrounding lymph node involvement, and extra-organ infiltration. Low-grade MALT lymphoma is initially confined to the gastric mucosa; therefore, it responds favorably to H. pylori eradication therapy. However, when the lymphoma invades the deep layers of the gastric wall and disseminates to local lymph nodes and distal sites, the tumor is no longer sensitive to H. pylori eradication therapy.

Of cancer-resembling lesions on endoscopy, 28.8% had MALT on histology in a study in Ife, Nigeria. H. pylori prevalence was approximately 95% among these cases, ^[7] another report from Maiduguri, Nigeria, showed about 85% H. pylori prevalence in gastric cancer patients, but the incidence of MALT was low. ^[3]

The index case however presented to us about 9 months after he had gastric surgery in a private clinic. He had palpable peripheral lymphadenopathy and abdominal ultrasound scan revealed enlarged para-aortic nodes. We deduced from this presentation that the disease was already disseminated before he had a surgical resection of the gastric tumor. Some workers, however, have demonstrated that up to 25 to 42.7% of cases of MALT may present with disseminated disease ^[8],[9] and as such, H. pylori eradication treatment may not cause regression of the tumor in such cases; this makes it necessary that each patient be vigorously investigated.

The index patient would have benefitted from an early endoscopy, biopsy, and histology of the specimen. Earlier initiation of combination chemotherapy would have given him a longer time of survival after diagnosis.

We wish to acknowledge the immense help of Prof. SO Nwosu of the Anatomical Pathology Department of University of Port Harcourt Teaching Hospital for diligently reviewing the histology slides of this patient and assisting in making the diagnosis.

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/1755-6783.85764