[1383] Multiple & Persistent Atypical NK-Cell Lymphoproliferative Lesions in Gastro-Intestinal (GI) Mucosa Mimicking NK-Cell Lymphoma. Clinico-Pathological Features & Follow-Up in a Unique Case Series

A Mansoor, S Pittaluga, I Auer, ES Jaffe. University of Calgary/Calgary Lab. Services (CLS), Calgary, AB, Canada; National Cancer Institute/NIH, Bethesda, MD

Background: Nasal NK/T cell lymphoma is an aggressive, EBV associated neoplasm with frequent GI involvement and is treated with high dose chemotherapy. In small biopsies morphological diagnosis can be challenging. We previously reported a patient (pt), with multiple, persistent, atypical NK cell lymphoproliferative lesions in the GI tract mimicking NK cell lymphoma. We now describe an expanded series of five very similar pts, in whom atypical NK-cell proliferative lesions were mis-diagnosed as NK cell lymphoma, resulting in invasive investigations and/or aggressive therapy.
Design: Pts were identified and clinical / laboratory data was obtained from institutional files (2006-2009). H&E stained FFPE tissue sections were reviewed. A standardized protocol for IHC staining was used. In situ hybridization for EBV (Novocastra) was performed on FFPE sections. TCR gene rearrangement was examined by PCR. Follow-up data was obtained.
Results: Pts were young (27-53 yrs; median 37 yrs; M:F 1:1.3). All pts presented with vague GI symptoms without evidence of celiac disease or IBD and only 1/5 had anti-gliadin antibodies. 2/5 pts had single site of involvement [stomach (1); colon (1)] while 3/5 pts had lesions at multiple sites (stomach /small intestine/ colon). Endoscopy showed tiny superficial, discrete, multiple, hemorrhagic lesions or small (1cm) patchy superficial ulcers. Histologic sections revealed diffuse but relatively superficial mucosal infiltration by atypical medium-sized lymphoid cells with finely clumped chromatin and focal destruction of mucosal glands. Phenotype was CD56+, TIA / Granzyme B +, CD3+ ; EBV studies were negative and TCR gene was germ line. Initial impression of NK/T-cell lymphoma was reported in all, resulting in invasive investigations including BM biopsy (2/5 pts). One pt received chemotherapy / BMT. Follow-up endoscopy/ biopsy showed persistent but non-progressive lesions in 3/5 pts. All pts are alive with median follow-up of 22 months.
Conclusions: We report, a unique entity characterized by persistent & multiple foci of NK-cell infiltration in GI mucosa, affecting young pts, with an indolent clinical course, and mimicking aggressive NK cell lymphoma on endoscopic biopsies. Recognition is crucial to avoid erroneous diagnosis, which may lead to inappropriate chemotherapy.
Category: Hematopathology

Monday, March 22, 2010 1:00 PM

Poster Session II # 141, Monday Afternoon


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