Teaching Case

A 75-year-old woman presented with increasing stomach pain, bloating and nausea during the past two months. No fever, night sweats or weight loss was observed. At clinical presentation, a 6-7 cm mass was palpated in the right upper abdomen. No evidence of suspicious lymph nodes at clinical examination.

Figures 1, 2 and 3: Diffuse and homogeneous gastric wall thickening in the distal part of the stomach. The surrounding fat plane is preserved. Infiltration of adjacent organs is not seen.
Figure 4: Mainly resolved gastric wall thickening after chemotherapy.

Background: The most common site of gastrointestinal lymphoma is the stomach. However, lymphoma accounts for only 5% of all gastric malignancies [1]. Lymphoma of mucosa-associated tissue (MALT) is a distinct entity within the group of extranodal lymphomas and is associated with helicobacter pylori infection and chronic gastritis [2]. Radiologically, lymphoma can be classified as infiltrative, ulcerative, polypoid, nodular or combined.

Imaging Perspective: The following imaging features aid in the differentiation from other malignancies. Gastric wall thickening is typically more diffuse and homogeneous than in adenocarcinoma. The fat plane around the stomach is also more likely to be preserved, as it was in our case. Rarely lymphoma leads to luminal narrowing and obstruction. The distal half of the stomach is more often involved. Moreover, in contrast to adenocarcinoma, lymphoma often affects more than one site of the stomach. Involvement of the caudal retroperitoneal lymph nodes suggests lymphoma rather than adenocarcinoma [3].
Gastrointestinal stromal tumour (GIST) of the stomach is commonly characterised as a well-circumscribed heterogeneous enhancing, round, exophytic tumour, manifesting as an extrinsic mass to the wall of the stomach. Neuroendocrine tumours tend to be submucosal, well-defined and enhancing [3]. The stomach is an unusual site for metastases. The most common primary tumours involved are malignant melanoma, breast and lung carcinoma [4].

Outcome: As in our case, treatment of MALT lymphoma consists of chemotherapy. Our patient had a partial remission after having received 6 cycles of R-CHOP (see Figure 4).