Atypical Lymphocytes
March 30th, 2020
Overview
The term atypical lymphocyte is used to refer to any abnormal lymphocyte that does not appear reactive. The presence of such cells in the peripheral blood suggests a neoplastic process, such as a lymphoid leukaemia or the leukaemic phase of lymphoma. These cells may be difficult to distinguish on morphological examination.
Causes of Atypical Lymphocytes
- Mature B cell leukaemias - CLL, B cell prolymphocytic leukaemia, hairy cell leukaemia, hairy cell leukaemia variant
- Leukaemic phase of B cell lymphomas - follicular lymphoma, mantle cell lymphoma, splenic marginal zone lymphoma, diffuse large B cell lymphoma, burkitt lymphoma
- Mature T cell neoplasms - T cell prolymphocytic leukaemia, T cell large granular lymphocytic leukaemia, adult T cell leukaemia / lymphoma, Sezary syndrome, anaplastic large cell lymphoma
Interpretation
- Chronic lymphocytic leukaemia - large numbers of small mature lymphocyes with smudge cells
- Hairy cell leukaemia - medium-sized cells with 'hairy' projections
- Follicular lymphoma - small cells with deeply clefted nuclei
- Splenic marginal zone lymphoma - 'polar' projections from two ends of the cell
- Diffuse large B cell lymphoma - large cells with cytoplasmic vacuoles
- Burkitt lymphoma - deeply basophilic cytoplasm with vacuoles
- T large granular lymphocytic leukaemia - medium-sized cells with the nucleus to one side of the cell, and azurophilic granules
- Sezary syndrome - 'cerebriform' nucleus (looks like a brain)
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