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Condition created 2026-08-25 · updated 2026-08-25
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Colorectal Lymphoma

Primary lymphoma arising in the colon or rectum — the wiki's first dedicated treatment of this topic (previously only a brief small-bowel-focused lymphoma passage existed, on Small Bowel Neoplasms, which explicitly flagged the absence of a general/colorectal lymphoma page as an open item; that gap is now closed by this page). Content below is from a textbook reference chapter (ASCRS Ch34 - GIST, Neuroendocrine Tumors, and Lymphoma), not primary literature.

Epidemiology and distribution

Primary extranodal lymphoma accounts for 10–30% of all lymphoma; the GI tract is the most common extranodal site. Colorectal lymphoma is rare within that already-uncommon category — less than 1% of colorectal neoplasms are lymphoma (contrast with the small bowel, where lymphoma is proportionally far more significant — up to 25% of small bowel malignant tumors per Small Bowel Neoplasms). Within the colorectum, the cecum is the most common site, likely reflecting the relatively high concentration of gut-associated lymphoid tissue (GALT) in that region — consistent with the small bowel's own GALT-driven predilection for the terminal ileum noted on Small Bowel Neoplasms.

Clinical presentation

Nonspecific — abdominal pain, change in bowel habits, weight loss, GI bleeding, or a palpable mass; can mimic colorectal adenocarcinoma or inflammatory bowel disease both clinically and endoscopically, making tissue diagnosis essential. Presentation may also be with an acute surgical complication (perforation, obstruction) rather than indolent symptoms.

Histology (WHO classification)

Table 34.5 in the source summarizes the WHO subtype breakdown. The two dominant subtypes each account for roughly 45% of colorectal lymphoma:

  • Extranodal marginal zone lymphoma (MALT-type) — typically indolent, B-cell lineage.
  • Diffuse large B-cell lymphoma (DLBCL) — more aggressive, B-cell lineage.

Less common subtypes, each discussed with subtype-specific notes in the source:

  • Follicular lymphoma — generally indolent, B-cell.
  • Mantle cell lymphoma — historically more aggressive B-cell subtype; the source notes it has a particular tendency toward multifocal GI involvement (lymphomatous polyposis pattern) when it involves the colorectum.
  • T-cell lymphoma — rare in the colorectum; generally more aggressive and less chemosensitive than B-cell subtypes, mirroring the B-cell-vs-T-cell chemosensitivity distinction already described for small bowel lymphoma on Small Bowel Neoplasms (B-cell lymphomas more chemosensitive, higher remission rates; T-cell lymphomas more resistant, more likely to progress to obstruction/ perforation).

Diagnosis and staging

  • Dawson criteria: the classic criteria distinguishing primary GI lymphoma from GI involvement by systemic/nodal lymphoma — requiring absence of peripheral lymphadenopathy at presentation, normal white cell count, predominant bowel lesion with only regional lymph node involvement at laparotomy, and no hepatic/splenic involvement (except by direct extension).
  • Imaging: PET/CT for staging and treatment-response assessment (similar role to its use in nodal lymphoma generally).
  • Bone marrow biopsy is part of the standard staging workup to exclude marrow involvement.
  • Staging system: a modified Ann Arbor staging system (Table 34.6) adapted for GI lymphoma, distinct from the AJCC TNM system used for colorectal adenocarcinoma (see Colorectal Cancer Staging (TNM)) — reflecting lymphoma's fundamentally different staging logic (nodal/extranodal spread pattern rather than depth-of-invasion/nodal-count).

Treatment

  • Localized disease: surgical resection combined with chemotherapy is the standard approach for localized colorectal lymphoma — supported by a South Korean 345-patient retrospective cohort and a smaller 40-patient prospective cohort, both showing benefit from the combined surgery-plus- chemotherapy approach over either modality alone.
  • Chemotherapy regimen: CHOP, with rituximab added for CD20-positive B-cell subtypes (R-CHOP) — standard systemic-lymphoma chemoimmunotherapy, applied here to the GI-lymphoma setting.
  • Radiation is generally avoided for colorectal lymphoma given the risk of significant bowel toxicity, in contrast to radiation's more established role in some other extranodal lymphoma sites.
  • Special scenarios:
  • Perforation at presentation requires emergent surgical management before systemic therapy can proceed.
  • Subacute perforation after chemotherapy initiation is a recognized risk — rapid tumor lysis / response in a large bulky lesion can thin the bowel wall and precipitate delayed perforation even after treatment has started, so patients require close monitoring during early chemotherapy.
  • Subtype-specific notes:
  • MALT lymphoma: often more indolent; may respond to less aggressive management in appropriate cases (consistent with MALT lymphoma's generally indolent behavior at other anatomic sites).
  • Follicular lymphoma: generally indolent course.
  • T-cell lymphoma: more resistant to therapy, worse prognosis — mirrors the small-bowel T-cell-lymphoma framing on Small Bowel Neoplasms.
  • Mantle cell lymphoma: historically more aggressive; multifocal/polyposis-pattern involvement when it affects the colorectum.

Open items / gaps

  • No primary literature yet in the wiki independently appraising the South Korean 345-patient cohort, the 40-patient prospective cohort, or R-CHOP efficacy specifically in colorectal lymphoma — currently only the textbook's narrative summary.
  • Table 34.5 (WHO subtype breakdown) and Table 34.6 (modified Ann Arbor staging) were summarized narratively above rather than fully transcribed — refer back to ASCRS Ch34 - GIST, Neuroendocrine Tumors, and Lymphoma if exact staging criteria or the full subtype percentage breakdown are needed clinically.
  • The small-bowel lymphoma content on Small Bowel Neoplasms and this page's colorectal-lymphoma content are complementary (different primary sites, same general disease biology) rather than duplicative — cross-linked in both directions.