Secondary mucosa-associated lymphoid tissue (MALT) lymphoma of the colon
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- Shaheen, S. & Guddati, A.K. Med Oncol (2013) 30: 502. doi:10.1007/s12032-013-0502-2
Mucosa-associated lymphoid tissue (MALT)-type lymphomas most commonly occur in the stomach and have been associated with Helicobacter pylori infection. However, MALT-type lymphoma of the colon is a rare entity. It commonly manifests with symptoms of weight loss, low-grade fever, constipation, melena, and hematochezia. Unlike gastric lymphoma, it is difficult to detect MALT-type lymphoma of the colon by imaging. Colonoscopy may reveal lesions whose biopsy most commonly shows abundant B lymphocytes. There is no universal immunohistochemistry profile for MALT-type lymphoma but CD 20 staining is commonly seen. Trisomies and translocations have been described and their presence has been correlated with treatment response. Due to the rarity of colonic MALT-type lymphoma, no standard guidelines are available for its management. It often occurs individually and rarely occurs simultaneously with concurrent colon adenocarcinoma. This case report describes the presentation and clinical course of a secondary MALT-type lymphoma in a patient who underwent colectomy for a prior colon adenocarcinoma.
Mucosa-associated lymphoid tissue is found in the gastrointestinal tract and is involved in immune surveillance . It occurs as isolated lymphoid follicles composed of mostly B lymphocytes. Tissues with similar function have been observed in the bronchial tree [bronchial-associated lymphoid tissue (BALT)], nose [nose-associated lymphoid tissue (NALT)], and vagina [vulvo-vaginal-associated lymphoid tissue (VALT)]. Specialized cells called M cells in the mucosal epithelium absorb, process, and present antigens to the subepithelial lymphocytes. These lymphocytes consisting of B cells, T cells, and dendritic follicular cells are collectively responsible for the effector mechanisms involving IgA and IgM immunoglobulins . Mucosa-associated lymphoid tissue lymphoma (MALT) was first described by Isaacson and Wright as a distinct type of lymphoma . The most common sites of occurrence of MALT-type lymphomas are the stomach, small intestine, and the colon . Notably, more than 90 % of MALT-type lymphomas of the stomach are associated with Helicobacter pylori infections . Autoimmune diseases like Sjogren’s syndrome and celiac disease have been proposed to play an etiological role in the development of MALT-type lymphoma. The clinical presentation is varied and may mimic symptoms of peptic ulcer disease. It may also present with generalized symptoms of weight loss, chronic fatigue, nausea, and anemia. The prognosis, especially for gastric MALT-type lymphomas, is stage dependent. Antibiotic therapy against H. pylori often results in an excellent remission in patients with gastric MALT-type lymphomas but also predisposes them to higher rate of gastric cancer and non-Hodgkin’s lymphoma . The therapeutic modality for MALT-type lymphoma of the colon is dependent on the presentation with surgical intervention being used for solitary lesions and chemotherapy being used for diffuse disease . MALT-type lymphoma of the colon may present as abdominal pain, constipation, melena, and hematochezia. It often occurs individually and has rarely been seen to occur simultaneously with concurrent colon adenocarcinoma. The detection of MALT-type lymphoma in patients with concurrent colon adenocarcinoma has been coincidental and has been a result of careful examination of colectomy specimens. The case described here involves the detection of a secondary MALT-type lymphoma in a patient who underwent colectomy for a prior colon adenocarcinoma.
Adenocarcinoma of the colon is the third most commonly diagnosed malignancy in the world . However, primary large bowel lymphomas constitute approximately 0.2 % of all large bowel malignancies. A male predominance of 1.5: 1 was noted on gastric MALT-type lymphomas but no such predominance was found in colonic MALT-type lymphomas [9, 10]. The etiology of MALT-type lymphoma in the stomach has been attributed to chronic infection, especially by H pylori . Specifically, H pylori strains expressing cytotoxin-associated gene A (CagA) have been shown to promote preneoplasia . However, the correlation between H pylori infection with colonic MALT-type lymphoma has not been proven conclusively. There have been conflicting reports that elimination of H pylori infection leads to resolution , regression of MALT-type lymphoma in spite of persistence of H pylori infection , and spontaneous regression of MALT-type lymphoma . This is especially true for patients with nodal disease who have been observed not to attain complete response with H pylori eradication [15–17]. Genetic abnormalities involving trisomies of chromosomes 3, 12, and 18 and translocations of t[11, 18][q21;q21], t[14, 18][q32;q21], t[1, 14][p22;q32], and t[3, 14][p14;q32] have also been observed. In the context of sustained antigenic stimulation, some of these abnormalities have been shown to activate the nuclear factor B (NF-B) oncogenic pathway .
Histological examination of MALT-type lymphomas often reveals lymphoepithelial lesions with irregular nuclei and hyperchromasia. Similar formations involving reactive lymphoid infiltrates may also appear in benign conditions involving inflammation. Lymphoid cells may expand in the lamina propria and occasionally infiltrate the muscularis mucosa. Infiltration through the muscularis propria may be manifested as mucosal ulcers. The case described here manifested in a similar manner. MALT-type lymphoma is notable for a preponderance of B cells which can be detected by CD 20 staining. These cells are negative for CD10, CD 23, and cyclin D1, and cells with plasmacytic differentiation may stain strongly for kappa and lambda chains . Due to the rarity of colonic MALT-type lymphoma, no standard guidelines are available for its management. Besides surgery and chemotherapy, radiotherapy has also been used to treat MALT-type lymphoma of the colon [20, 21]. Simultaneous occurrence of MALT lymphoma and adenocarcinoma is rare with only a few cases reported so far in the medical literature [22, 23]. The patient described in this case report had right-sided hemicolectomy, and it is possible that the decreased length of the colon may have enhanced the immunologic reaction to an unknown antigen and precipitated MALT-type lymphoma. It is rare to detect a secondary MALT-type lymphoma after successful resection of the primary adenocarcinoma of the colon. This case illustrates the need for heightened awareness of the possibility of development of secondary malignancies, especially MALT-type lymphoma after hemicolectomy.
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