Among non-Hodgkin lymphomas, which is the most common site of extranodal involvement?
A. Bone marrow
B. Central nervous system
C. Gastrointestinal tract
D. Liver
Explanation
Extranodal NHL: Most Common Sites
Key Point
The gastrointestinal (GI) tract is the most common site of extranodal involvement in non-Hodgkin lymphomas, accounting for 5–20% of all NHL presentations and up to 40% of extranodal NHLs.
Frequency of Extranodal Sites
Table
Site
Frequency
Notable Type
Gastrointestinal tract
5–20% of all NHLs; 40% of extranodal
MALT lymphoma (stomach), EATL
Bone marrow
~25% at diagnosis (often occult)
SLL/CLL, follicular lymphoma
Liver
5–10%
Hepatosplenic T-cell lymphoma
CNS
2–5% (higher in immunocompromised)
PCNSL, lymphoblastic
Bone
2–5%
Primary bone lymphoma (rare)
Testis
1–2%
Primary testicular lymphoma
High-YieldNEET PG
GI involvement is most clinically apparent because:
Presents with abdominal pain, obstruction, bleeding, or perforation
Often requires endoscopy and biopsy for diagnosis
MALT lymphoma of stomach is strongly associated with H. pylori infection
Clinical Pearl: Bone Marrow Involvement
Warning
Bone marrow involvement is actually present in ~25% of NHL cases at diagnosis but is often occult (found only on staging marrow biopsy). However, GI tract is the most clinically significant and most frequently diagnosed extranodal site because it causes symptoms and is accessible to endoscopy.
GI Lymphomas: Subtypes
1.
MALT lymphoma (stomach) — associated with H. pylori; may regress with eradication
2.
Enteropathy-associated T-cell lymphoma (EATL) — associated with celiac disease
3.
Burkitt lymphoma — can present with bowel obstruction or perforation
4.
DLBCL — can involve any GI segment
Mnemonic: "GI is the Gateway" — Gastrointestinal tract is the gateway for extranodal NHL.
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