Contributed by Arivarasan Karunamurthy, MD. and Raymond Felgar, MD, PhD
An 80-year old male with a past medical history of dyslipidemia, hypertension, gout and prostate cancer was evaluated for peripheral blood lymphocytosis.
The complete hemogram (Fig. 1) and peripheral blood smear (Fig. 2) demonstrated absolute lymphocytosis, including many large granular lymphocytes (Fig. 3), some intermediate in size with abnormal nuclear contours. Based on a 100-cell lymphocyte count, 66% of all lymphocytes were large granular lymphocytes. Absolute large granular lymphocyte count = 6,461 per microliter.
A bone marrow aspirate showed hypercellular marrow with a normal differential (Figs. 4 and 5) on biopsy and touch imprints (Fig. 6) showed an increased number of large granular lymphocytes.
Bone marrow biopsy (Fig. 7) and particle preparation (Fig. 8) showed 30-40% cellularity with a diffuse increase in small lymphocytes that focally form small, ill-defined aggregates, with a normal M:E ratio, complete maturation in all lineages and adequate megakaryocytes
Immunohistochemical stains performed on bone marrow biopsy showed an increase in CD3, CD2, CD5, CD7 and CD8 positive T cells forming ill defined aggregates and also a few scattered CD56, CD57, TIA1 & Granzyme B positive cells (Figs. 9 and 10)
Flow cytometry studies (Fig. 11) performed on the bone marrow demonstrated 46% bright CD45+ (lymphocyte) events and 3% CD14+ monocytes. T and NK cell marker analysis (Fig. 12) shows a prominent population (26-30% of total) of NK-like T-cells with CD2+, CD3+, CD5+, CD7 (dim+), CD56+, CD16/57+, CD4-, CD8+, T-cell receptor alpha-beta+ immunophenotype (highlighted in blue on Fig.12).
Cytogenetic studies showed a normal male karyotype 46,XY , molecular studies showed that Southern Blot (Fig. 13, positive bands [white arrow] ) and PCR (Fig. 14, positive bands in V1-8 & V9 [rose arrows] ) were positive for clonal β chain and γ chain T-cell receptor gene rearrangements, respectively.