![A 72-year-old man presented with a persistent lymphocytosis. Physical examination was unremarkable, with no evidence of lymphadenopathy or organomegaly. A marked lymphocytosis (11.4 × 109/L) and slight anemia (12.0 g/dL) were observed. The peripheral blood smear showed 70% atypical lymphocytes of medium size, with a condensed chromatin, often small nucleoli, and a weakly basophilic cytoplasm containing clustered granulations, with a large granular lymphocyte morphology (May-Grünwald-Giemsa stain, original magnification ×1000). Unexpectedly, in immunophenotyping analysis, 71% of lymphocytes were of B origin, expressing CD19, CD20, CD79b (bright), FMC7, CD5 (partial), CD23, and a κ (bright) light chain restriction. Physiologic distributions of TCD4+, TCD8+, and natural killer (NK) lymphocytes (15%, 9%, and 4% of lymphocytes, respectively) were observed, excluding a T or NK origin of the granular lymphocytes observed in the peripheral blood smear. A 46,XY,del(3)(p12),der(5)t(5;?)(p15;?),del(17)(p11)[12]/46,idem,inv(6)(p22q16),del(7)(q21)[2]/46,XY[1] was observed. Fluorescent in situ hybridization analysis demonstrated a TP53 17p13 locus deletion and no IGH/CCND1 rearrangement. CCND1 was not overexpressed by quantitative reverse-transcriptase polymerase chain reaction. All of these features were consistent with a B-cell lymphocytosis of marginal zone type, with atypical morphological features mimicking large granular lymphocytes. The patient remains stable 9 months after the diagnosis. / This case illustrates that cytology can sometimes be misleading, and it highlights the importance of integrating all biological results to establish an accurate diagnosis.](https://ash.silverchair-cdn.com/ash/content_public/journal/blood/131/2/10.1182_blood-2017-09-807933/4/m_blood807933f1.jpeg?Expires=1735601514&Signature=SmarhYcFqF91J-2vhMgyDzYXvlS8QDga8RoHz64QOjQDRZ7wXlHslNbXIlmnA-3GJySQ8SetUleCyYIZFgmG1t~DWYhwkFG4ubRmyouJOklvns-SztR3NFxacmtABMC6aW9CcKgdC9pMUwp5AwWzXHG4wC0hZeQlfKMSpYn4Gqapex8KMtbRGep-g8xYj0G53CPi1nskg3J9gcU03XE2dVRBicAayHgpVkE5N0ObWDh~4uypC1Lif0u5ekjaPuX8nWQ6dE2ll-P2Bg2xrj2K-nsmIT0sq2fnmiE7esJkoAf34KHhuj8waI~ueq8bbzqLAB1udDfi2DWaIFUehuwFGw__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
A 72-year-old man presented with a persistent lymphocytosis. Physical examination was unremarkable, with no evidence of lymphadenopathy or organomegaly. A marked lymphocytosis (11.4 × 109/L) and slight anemia (12.0 g/dL) were observed. The peripheral blood smear showed 70% atypical lymphocytes of medium size, with a condensed chromatin, often small nucleoli, and a weakly basophilic cytoplasm containing clustered granulations, with a large granular lymphocyte morphology (May-Grünwald-Giemsa stain, original magnification ×1000). Unexpectedly, in immunophenotyping analysis, 71% of lymphocytes were of B origin, expressing CD19, CD20, CD79b (bright), FMC7, CD5 (partial), CD23, and a κ (bright) light chain restriction. Physiologic distributions of TCD4+, TCD8+, and natural killer (NK) lymphocytes (15%, 9%, and 4% of lymphocytes, respectively) were observed, excluding a T or NK origin of the granular lymphocytes observed in the peripheral blood smear. A 46,XY,del(3)(p12),der(5)t(5;?)(p15;?),del(17)(p11)[12]/46,idem,inv(6)(p22q16),del(7)(q21)[2]/46,XY[1] was observed. Fluorescent in situ hybridization analysis demonstrated a TP53 17p13 locus deletion and no IGH/CCND1 rearrangement. CCND1 was not overexpressed by quantitative reverse-transcriptase polymerase chain reaction. All of these features were consistent with a B-cell lymphocytosis of marginal zone type, with atypical morphological features mimicking large granular lymphocytes. The patient remains stable 9 months after the diagnosis.
This case illustrates that cytology can sometimes be misleading, and it highlights the importance of integrating all biological results to establish an accurate diagnosis.
A 72-year-old man presented with a persistent lymphocytosis. Physical examination was unremarkable, with no evidence of lymphadenopathy or organomegaly. A marked lymphocytosis (11.4 × 109/L) and slight anemia (12.0 g/dL) were observed. The peripheral blood smear showed 70% atypical lymphocytes of medium size, with a condensed chromatin, often small nucleoli, and a weakly basophilic cytoplasm containing clustered granulations, with a large granular lymphocyte morphology (May-Grünwald-Giemsa stain, original magnification ×1000). Unexpectedly, in immunophenotyping analysis, 71% of lymphocytes were of B origin, expressing CD19, CD20, CD79b (bright), FMC7, CD5 (partial), CD23, and a κ (bright) light chain restriction. Physiologic distributions of TCD4+, TCD8+, and natural killer (NK) lymphocytes (15%, 9%, and 4% of lymphocytes, respectively) were observed, excluding a T or NK origin of the granular lymphocytes observed in the peripheral blood smear. A 46,XY,del(3)(p12),der(5)t(5;?)(p15;?),del(17)(p11)[12]/46,idem,inv(6)(p22q16),del(7)(q21)[2]/46,XY[1] was observed. Fluorescent in situ hybridization analysis demonstrated a TP53 17p13 locus deletion and no IGH/CCND1 rearrangement. CCND1 was not overexpressed by quantitative reverse-transcriptase polymerase chain reaction. All of these features were consistent with a B-cell lymphocytosis of marginal zone type, with atypical morphological features mimicking large granular lymphocytes. The patient remains stable 9 months after the diagnosis.
This case illustrates that cytology can sometimes be misleading, and it highlights the importance of integrating all biological results to establish an accurate diagnosis.
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![A 72-year-old man presented with a persistent lymphocytosis. Physical examination was unremarkable, with no evidence of lymphadenopathy or organomegaly. A marked lymphocytosis (11.4 × 109/L) and slight anemia (12.0 g/dL) were observed. The peripheral blood smear showed 70% atypical lymphocytes of medium size, with a condensed chromatin, often small nucleoli, and a weakly basophilic cytoplasm containing clustered granulations, with a large granular lymphocyte morphology (May-Grünwald-Giemsa stain, original magnification ×1000). Unexpectedly, in immunophenotyping analysis, 71% of lymphocytes were of B origin, expressing CD19, CD20, CD79b (bright), FMC7, CD5 (partial), CD23, and a κ (bright) light chain restriction. Physiologic distributions of TCD4+, TCD8+, and natural killer (NK) lymphocytes (15%, 9%, and 4% of lymphocytes, respectively) were observed, excluding a T or NK origin of the granular lymphocytes observed in the peripheral blood smear. A 46,XY,del(3)(p12),der(5)t(5;?)(p15;?),del(17)(p11)[12]/46,idem,inv(6)(p22q16),del(7)(q21)[2]/46,XY[1] was observed. Fluorescent in situ hybridization analysis demonstrated a TP53 17p13 locus deletion and no IGH/CCND1 rearrangement. CCND1 was not overexpressed by quantitative reverse-transcriptase polymerase chain reaction. All of these features were consistent with a B-cell lymphocytosis of marginal zone type, with atypical morphological features mimicking large granular lymphocytes. The patient remains stable 9 months after the diagnosis. / This case illustrates that cytology can sometimes be misleading, and it highlights the importance of integrating all biological results to establish an accurate diagnosis.](https://ash.silverchair-cdn.com/ash/content_public/journal/blood/131/2/10.1182_blood-2017-09-807933/4/m_blood807933f1.jpeg?Expires=1735601515&Signature=3FEAQGwsEjd5YiA8k-CK7rAAbs2J~f9Rv6vjBd8my5BsssI7HDtYhASgFKkP2TJb5xbBLSsbMK5zSdbJ~ERoCk3cUvHlW6SofhD7SYJO~ABGhY~ADGh8SWYXCZcInFAUM2E2ZMNJx9Ewry5XPMQiRtv-spvwnL5NA8S5f8iGoe9DJ86pRBbeEsbzaCjp3per2WAtS3vxSqulgrH8aIRcqn2oyCe4SFAQSvlhcIHYowGUJBG9gtsTvKUaX0EtysZLFMs3vHc9Zm84rxdf2cixMbWZRc0Hvr7O5Zmopin9AYum6RaKVVbeY4b9GC14NKs~pfHIQdd8JE7JmDpNM5d-eg__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
