TBA (24W188)

Standing Out from the Crowd; Aberrant and Clonal Variations in RCDII

Author(s)

C Walker, A Hayat, M O’Donnell, V Byrnes

Department(s)/Institutions

Gastroenterology Department, University Hospital Galway, Ireland

Introduction

The presence of an aberrant clonal intraepithelial lymphocytes (IEL) population is the hallmark of RCDII. We have observed patients who have clinical features of RCDII but do not fit the classical immunophenotypic or molecular features of RCDII.

Aims/Background

To describe the profile of RCDII patients who present with classical aberrancy in the absence of clonality or atypical aberrancy +/- clonality.

Method

A retrospective review of flow cytometry and TCR-GR analysis of RCDII patients over a 14-year period.

Results

13 RCDII patients were identified. Median age at RCDII diagnosis was 62 years. 6 patients had classical RCDII, with a median of 80% aberrant IELs(cytoCD3+/sCD3-/sCD8-) and had clonal TCR-GR. Of the remaining 7 patients: o 4 had classical aberrancy(median 52%) without clonality, including: • One who lost the TCR-GR clone 1 year post autologous stem cell transplant but whose aberrancy persisted(43%) 10 years later. • One who subsequently developed clonal TCR-GR on follow up. o 1 patient has a mixed aberrant IEL population(71% cytoCD3+/sCD3-/sCD8+, 19%cytoCD3+/sCD3-/sCD8-) but has clonal TCR-GR. o 2 patients had atypical aberrant IEL population without clonal TCR-GRs, including: • One who developed lymphoma 3 years post RCDII diagnosis • The other remains under surveillance (16% classical aberrancy, 41%NK cells). Mortality rate for the classical RCD II was 66% compared to 14% in variant RCD II.

Conclusions

The heterogeneity of RCDII poses many diagnostic challenges. Newer sequencing technologies will aid the expansion of the diagnostic criteria to Include variant RCDII. While follow up is ongoing, variant RCDII may be associated with a lower mortality.