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Morphological and immunophenotypical features of hairy cell leukaemia involving lymph nodes and extranodal tissues
Author(s) -
Cortazar Jacqueline M,
DeAngelo Daniel J,
Pinkus Geraldine S,
Morgan Elizabeth A
Publication year - 2017
Publication title -
histopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.626
H-Index - 124
eISSN - 1365-2559
pISSN - 0309-0167
DOI - 10.1111/his.13206
Subject(s) - pathology , lymph , nodal , bone marrow , medicine , b cell , red pulp , differential diagnosis , hairy cell leukemia , neoplasm , spleen , leukemia , antibody , immunology
Aims Hairy cell leukaemia ( HCL ) is a rare B cell neoplasm that mainly affects bone marrow ( BM ), peripheral blood ( PB ) and spleen. Involvement of lymph nodes and extranodal structures is considered infrequent. Herein we describe our institutional experience of nodal ( n = 10) and extranodal ( n = 3) HCL during a 30‐year period. Methods and results Ten patients had prior evidence of HCL within the BM or PB at a median 35.8 months before nodal/extranodal diagnosis (range: <1–175 months), and HCL was diagnosed concurrently within the bone marrow of one additional patient. Nodal involvement showed distinct architectural patterns, including diffuse (62% of cases), sinusoidal (25%) and nodular (13%). Extranodal involvement was characterized as diffuse infiltration through underlying structures in all cases. Morphological features ranged from classic ‘fried‐egg’ cytology to a plasmacytoid appearance. Nodal/extranodal disease showed an overlapping immunophenotypical profile with other small B cell lymphomas, including expression of cyclin D1 (70%), CD 43 (55%), CD 10 (38%) and CD 5 (8%). Rates of both CD 43 and CD 10 reactivity were higher than described previously in leukaemic HCL , suggesting that expression may be enriched in cases with extramedullary extension. Conclusions Although uncommon, HCL should be considered in the differential diagnosis of small B cell neoplasms involving nodal/extranodal sites, given the therapeutic implications. In particular, recent discoveries including detection of the BRAF V600E mutation in nearly all cases of HCL and the availability of an antibody to CD 103 for use in paraffin‐embedded tissues will facilitate the distinction of HCL from other small B cell lymphomas in the nodal/extranodal setting.