hairy cell leukemia ( hcl ) is an uncommon , indolent , b - cell leukemia that usually presents with chronic fatigue , right upper quadrant pain , splenomegaly , bleeding , and infections secondary to cytopenias . malignant cells with cytoplasmic projections are seen in the bone marrow , spleen , and at low levels in circulation [ 1 , 2 , 3 ] . there are approximately 1,000 and 1,600 new cases of hcl per year in the us and europe , respectively . the prevalence of the disease is unknown , although it likely exceeds the yearly hcl incidence . hcl is diagnosed based on blood counts including thrombocytopenia , anemia , leukopenia , neutropenia , monocytopenia , and characteristic immunohistologic ( ihc ) and cell - morphologic studies showing cells with cytoplasmic projections , oval or indented nuclei (  bean - shaped ) , and a  fried egg appearance on bone marrow biopsy due to abundant pale blue cytoplasm [ 5 , 6 , 7 ] . a 73-year - old male presented with a diagnosis of acute respiratory and renal failure , a large abdominal mass , ascites , a white blood cell count of 8.09  10/l , a hemoglobin value of 12.5 g / dl , and a hematocrit value of 36.1% . his past medical history included splenectomy , hypertension , and a diagnosis of hcl from 12 years earlier . prior to admission the patient had a 1-month history of positional discomfort , with occasional nausea and vomiting , and a 1-week history of painless jaundice . abdominal axial computed tomography ( ct ) with intravenous and gastrointestinal contrast revealed a large retroperitoneal mass encasing the superior mesenteric artery , displacing the stomach and infiltrating into the liver ( fig . the patient was transferred to the medical intensive care unit for further management and placed on a ventilator . after discussion with the attending physician , the family requested the patient be extubated and pronounced  do not resuscitate. the patient died the following day . autopsy revealed moderate ascites consisting of serosanguineous fluid ( 550 ml ) and 2 retroperitoneal masses . the first mass was 3.5 cm below the xyphoid process and measured 7.7  5.0  3.5 cm . the second mass was immediately below the first and measured 16.0  10.0  9.5 cm . approximately 80% of the larger mass was removed and weighed 825 g. no nodal enlargement was found below the aortic bifurcation . histologic examination of the mass by standard hematoxylin and eosin ( he ) staining revealed extensive hcl cells ( fig . additionally , ihc analysis revealed that the tumor cells were cd20 and tartrate - resistant acid phosphatase ( trap ) positive ( fig . the ihc analysis was performed in the lsu health shreveport pathology histology immunohistochemistry procedures pathology services using antibodies from cell marque ( rocklin , calif . later bouroncle et al .   described it as a distinct clinicopathologic entity , and in 1966 schrek and donnelly gave it its present name . hcl is an indolent , chronic , b - cell , lymphoproliferative disorder involving the bone marrow and spleen , often accompanied by reactive marrow fibrosis and peripheral blood cytopenias , especially monocytopenia [ 2 , 5 , 6 , 7 ] . hcl is an expansion of phenotypically activated mature b cells , expressing cd19 , cd20 , cd22 , cd25 , dba.44 , annexin a1 , cd11c , and cd103 , with clonal immunoglobulin gene rearrangements and monoclonal surface immunoglobulins . the cells are also trap positive , although this test is now less often performed [ 5 , 6 , 7 ] . although generally considered cd10 and cd5 negative , weak cd10 and cd5 expression is seen in approximately 26 and 5% of hcl , respectively . chromosomal abnormalities have been documented in hcl ; however , none are recognized as specific to hcl , although the disease does show the braf - v600e - activating mutation in the majority of cases [ 1 , 5 , 6 , 7 , 8 , 9 ] . while lymphadenopathy occurs in approximately 20% of all individuals with hcl , it is not usually considered clinically significant [ 1 , 5 , 6 , 7 ] . massive retroperitoneal lymphadenopathy in hcl is extremely uncommon , with most examples limited to case reports [ 10 , 11 , 12 ] . the largest study , based on 12 cases , found massive retroperitoneal lymphadenopathy typically followed long - standing disease , with an average appearance 9 years after hcl diagnosis ( range 325 years , 8/12 cases ) , extensive bone marrow involvement ( 12/12 cases ) , with retroperitoneal lymphadenopathy measuring 420 cm , with bulkier disease more likely to involve the hepatic porta , gastric outlet , and pancreas , and little or no nodal enlargement below the aortic bifurcation ( 12/12 cases , 1012 ) . 11/12 patients received chemotherapy prior to retroperitoneal lymphadenopathy development and only 1 patient initially presented with massive retroperitoneal lymphadenopathy . other case reports describe similar findings , one with massive retroperitoneal lymphadenopathy being a terminal event after a long disease course , as in our case [ 10 , 11 , 12 , 13 ] . two of these studies suggested that vasculitis accompanies hcl retroperitoneal lymphadenopathy [ 11 , 13 ] , while the larger study by mercieca et al .   suggested that in some of these patients lymphadenopathy follows a change in the disease as reflected by the resistance to chemotherapy and histologically by the appearance of larger , more primitive cells . the location of the lymphadenopathy , however , is very similar to that given in previous reports [ 10 , 11 , 12 , 13 ] . our findings suggest that hcl with massive lymphadenopathy appears after an unusually long disease course and has a predilection for the retroperitoneum above the aortic bifurcation and below the diaphragm , but it is not necessarily accompanied by vasculitis or a change away from the typical hcl histology .
hairy cell leukemia ( hcl ) is uncommonly associated with lymphadenopathy , while retroperitoneal lymphadenopathy is extremely uncommon . 
 we report on a patient with a 12-year history of hcl who developed painless jaundice and ascites , accompanied by positional discomfort with persistent nausea . 
 computed tomography examination revealed 2 large retroperitoneal masses , which at autopsy consisted of hcl with focally intermixed pancreatic and peripancreatic tissue . 
 lymphadenopathy was not identified above the diaphragm or below the aortic bifurcation . 
 no vasculitis or an unusual hcl histology was identified . as previous reports 
 , our findings suggest that hcl with massive lymphadenopathy has a specific site predilection , but it is not necessarily accompanied by vasculitis or an unusual histology .