Simultaneous Occurrence of Early Gastric Carcinoma and Mucosa-Associated Lymphoid Tissue Lymphoma of the Omentum
A 55-year-old woman was referred to our hospital with a history of appetite loss, right inguinal pain and weight loss. Endoscopy revealed a type 0-IIc tumor in the forecourt of the pylorus and entire wall thickening in the pylorus. Biopsy showed it to be signet ring cell carcinoma. H. pylori antigen in the urine was positive. Laboratory tests including blood counts, liver and renal function tests, tumor markers such as carcinoembryonic antigen and carbohydrate antigen 19-9 were within normal limits. Upper gastrointestinal series showed the tumor limited in the stomach. Computed tomography showed no lymph node swelling or distant metastasis. Therefore, distal gastrectomy with D2 lymph node resection was performed under the diagnosis of gastric carcinoma T1N0M0 (fig. ). During operation a mass 2.0 × 3.0 cm in size was observed in the omentum near the cecum. The mass was also resected for pathological examination. The postoperative course was uneventful, and the patient was discharged on the 16th postoperative day. Pathological review of the surgical specimen showed three independent early gastric cancer (No. 1: 0-IIc, T1b(sm), sig.; No. 2: 0-IIc, T1b(sm), sig.; No. 3: 0-IIc, T1a(m), sig.) (fig. ). No regional lymph node metastases were seen. Grossly, the peritoneal lesion showed a tumorous growth measuring 2.0 × 3.0 cm (fig. ). Microscopically, the lesion was composed of tumorous proliferation of small lymphocytes (fig. ). The lymphoid cells were composed of centrocytic and monocytic lymphoma. Little atypia was seen. A few mitotic figures were present. No lymphoepithelial lesions were seen because it was a peritoneal lesion. Plasmacytic differentiation was noted. Immunohistochemically, the lymphoid cells were positive for CD20 (+++) (fig. ), CD79a (++), CD138 (++) (fig. ), Ki67 (labeling = 10%) (fig. ), CD45RO (+), l-chain (+++), k-chain (+) and CD15 (+++), and negative for cytokeratin AE1/3, cytokeratin CAM5.2, CD3, CD30 (fig. ), CD10, CD34, CD56 and p53. The stainings of the light chains suggested positive light chain restriction. The diagnosis of primary omental MALT lymphoma was made. Due to the nature of this patient's disease, she was started on medical eradication of H. pylori.