9,10) It is thought that the clonal IELs seen in RCD may represent a low-grade lesion or EATL in-situ that may progress to outright EATL.
Type II EATL (monomorphic variant) represents approximately 10% to 20% of all EATL.
The 2 variants of EATL do show some overlap in terms of their molecular genetic findings.
Patients with both types of EATL frequently present with small intestinal perforation or bowel obstruction, abdominal pain, weight loss, and diarrhea.
The classic variant of EATL shows a wide range of tumor cell cytology.
A diagnostic approach that combines an expectation of common entities, such as reactive lymphoid aggregates, DLBCL, and MALT lymphoma, with maintenance of a "weather eye" for more unusual entities or appearances, such as double-hit lymphomas, EATL
, and complete plasmacytic differentiation, is crucial to successful navigation of the sea of lymphoid infiltrates arising in the gastrointestinal tract.
38,78) The type II form of EATL usually expresses CD8 and CD56 in contrast to expression of CD8 in only 20% and CD56 in fewer than 10% of cases of the more classic form of EATL.
In Northern Europe, EATL generally is regarded as a complication of celiac disease, but in some patients no history of malabsorption exists and villous atrophy and crypt hyperplasia are discovered only at the time of lymphoma resection.
The differential diagnosis of EATL includes not only large B-cell lymphoma of intestine, but also other forms of T-cell lymphoma including peripheral T-cell lymphoma NOS, anaplastic large cell lymphoma, and extranodal NK/ T-cell lymphoma, nasal type.
One caveat is that EATL and extranodal NK/T-cell lymphoma must be distinguished from 2 similar, if not identical, newly described entities, "K-cell enteropathy" or "ymphomatoid gastropathy," especially in small endoscopic biopsy specimens.
Classification of Gastrointestinal Lymphomasa B Cell Extranodal marginal zone, MALT type IPSID (heavy chain disease) Others (lymph node equivalents) Mantle cell (lymphomatous polyposis) Follicular Large B cell, NOS (~40% extranodal) Burkitt T Cell Enteropathy associated (EATL) Classic and type II Others (non-enteropathy associated) NK/T, nasal type [gamma][delta] ALCL Abbreviations: ALCL, anaplastic large cell lymphoma; EATL, enteropathy-associated T-cell lymphoma; IPSID, immunoproliferative small intestinal disease; MALT, mucosa-associated lymphoid tissue; NK, natural killer; NOS, not otherwise specified.