Atypical lymphocytes & atypical lymphoid cells [HS0146]

Atypical lymphocytes refer to reactive lymphocytes in viral, parasitic or mycotic infection. They vary in size from near-normal to very large. They may be oval or round with regular outline, or scalloped to assume the contour of juxtaposed erythrocytes. The nucleus may be round, oval, kidney bean-shaped, or lobulated; nucleoli may cause the cells to resembling malignant blast cells. The nuclear chromatin is less densely clumped than that of normal lymphocytes. The cytoplasm is basophilic and may contain vacuoles and scattered, small, pink-staining azurophilic granules. (Reference: J.A. Koepke. Practical Lab. Hematology. Churchill Livingstone. p.80). Atypical lymphocytes should be distinguished from atypical lymphoid cells that are generally used to describe atypical cells of the lymphocytic lineage in lymphomas or malignancies.

Atypical lymphocytes	Atypical lymphoid cells
l            They present as a heterogeneous population. l            Both large and small lymphocytes are present. l            Some lymphocytes contain cytoplasmic basophilia, whereas others do not. l            Some lymphocytes with dense nuclear chromatin and some with open chromatin. l            The cytoplasm of lymphocytes is frequently indented.	l            They are associated with malignancies. l            They are more uniform in size. l            The nuclear chromatin pattern is uniform. l            Cytoplasm features are homogeneous. l            Cleaved or clefted nucleus is frequent.

 

Reference:

Caldwell CW and Lacombe F.  Evaluation of peripheral blood lymphocytosis.  Academic Information System, USA, 2000.