Meningeal involvement in early stage chronic lymphocytic leukemia

Leukemic infiltration of the optic nerve in chronic lymphocytic leukemia: A case report and review of literature

Ophthalmic and neurologic involvement are rare complications of CLL, with few cases reported in the literature. We report a case of CLL with leukemic infiltration of the optic nerve and review of literature focusing on management and outcomes. A patient with heavily pretreated CLL presented to our hospital with progressive eye pain and was found to have infiltrative optic neuritis. CSF analysis confirmed involvement with CLL. After systemic treatment with R-CHOP and high-dose methotrexate, along with intrathecal cytarabine and hydrocortisone, she experienced significant improvement and was discharged home. Given the rarity of ophthalmic involvement in CLL, we reviewed all 15 previously reported cases of CLL with optic neuropathy as the first manifestation of CNS involvement and discussed the range of treatment options used and their respective outcomes.

Optic neuropathy due to chronic lymphocytic leukemia: The first manifestation of the disease

Purpose

Chronic lymphocytic leukemia (CLL) is the most common lymphoproliferative disorder in the western world. The involvement of the central nervous system (CNS) or the optic nerve in CLL, however, is rare. We report a case of a previously untreated patient with CLL whose first manifestation of the disease was a progressive visual loss caused by optic neuropathy.

Observations

Clinical manifestations, optical coherence tomography (OCT), and automated visual fields pointed to the diagnosis of neuropathy. Leukemic involvement of the CNS was confirmed after cells suggestive of CLL were found by cerebrospinal fluid analysis. Optic nerve infiltration is thought to be the cause of this optic neuropathy, and the clinical course and treatment are described herein.

Conclusions

When readily diagnosed, optic nerve infiltration is a rare, yet manageable complication of CLL.

Leptomeningeal Carcinomatosis in Chronic Lymphocytic Leukemia: A Case Report and Review of the Literature

Leptomeningeal disease is a rare complication of chronic lymphocytic leukemia (CLL). We report a case of leptomeningeal disease in CLL with a complete clinical response and clearance of cerebral spinal fluid (CSF) after treatment with ibrutinib and intrathecal rituximab. In a comprehensive review of the published literature since 1976, we found 136 cases of CLL with leptomeningeal spread. We found that leptomeningeal disease in patients with CLL responds favorably to treatment in most cases and is associated with longer overall survival than is expected for other cancers. Clearance of CSF is associated with improved survival. Treatment with rituximab and ibrutinib is more frequently associated with complete response compared with older agents. IMPLICATIONS FOR PRACTICE: The incidence of leptomeningeal CLL is more common than previously described and can be recognized by attention to certain symptoms and signs. This case presentation and literature review reveals that, in many cases, leptomeningeal lymphomatosis is reversible with the use of rituximab and ibrutinib. The authors show a survival benefit associated with treating to cerebral spinal fluid (CSF) clearance by cytology and compare outcomes with various treatment strategies, focusing on novel agents. Now that there is effective therapy for leptomeningeal lymphoma in CLL, the importance for oncologists to recognize this neurologic complication has become clear.

Leptomeningeal involvement in B-cell chronic lymphocytic leukemia: a case report and review of the literature

BACKGROUND

Central nervous system involvement is considered a rare complication of chronic lymphocytic leukemia, and so there is the risk of being overlooked.

CASE PRESENTATION

We report a case of central nervous system involvement in a 75-year-old mulatto woman with chronic lymphocytic leukemia after 5 years of follow-up and a literature review on the subject. The clinical course, treatment and outcome are described. A systematic, meticulous and comprehensive analysis of existing publications regarding chronic lymphocytic leukemia with central nervous system involvement was performed.

CONCLUSION

We concluded that central nervous system involvement of chronic lymphocytic leukemia is probably not associated with any evident risk factors. Diagnostic approach differs by institutions but often includes imaging, morphology and flow cytometry. Resolution of central nervous system symptoms can usually be accomplished with intrathecal chemotherapy or irradiation followed by systemic treatment. The recognition of this entity by clinicians could lead to early detection and treatment, resulting in better outcomes in this rare complication.

Central nervous system involvement of T-cell prolymphocytic leukemia diagnosed with stereotactic brain biopsy: case report

Prolymphocytic leukemia (PLL) is a generalized malignancy of the lymphoid tissue characterized by the accumulation of monoclonal lymphocytes, usually of B cell type. Involvement of the central nervous system (CNS) is an extremely rare complication of T-cell prolymphocytic leukemia (T-PLL). We describe a case of T-PLL presenting with symptomatic infiltration of the brain that was histopathologically proven by stereotactic brain biopsy. We emphasize the importance of rapid diagnosis and immediate treatment for patients presenting with CNS involvement and a history of leukemia or lymphoma.

Extramedullary chronic lymphocytic leukemia: systematic analysis of cases reported between 1975 and 2012

The prognostic significance of extra-medullary chronic lymphocytic leukemia (EM-CLL) is unknown. We conducted a Medline database systematic search analyzing English language articles published between 1975 and 2012 identifying 192 cases. Patients with EM-CLL were more commonly treated than not (p < .001). Skin and central nervous system (CNS) were the most commonly reported sites of organ involvement. Survival after diagnosis of EM-CLL appeared to depend on the site of EM involvement. Prospective evaluation and further studies of EM-CLL are warranted.

Spectrum of neurologic complications in chronic lymphocytic leukemia

Neurologic disease is believed to be an unusual complication during the course of chronic lymphocytic leukemia. Nevertheless, it has already been proven in autopsy series that the incidence of occult nervous system infiltration is much higher than was previously expected. The advent of more potent drugs to treat this lymphoproliferative disorder has brought a new hope for a possible cure in the future. However, an appropriate systemic treatment for central nervous system infiltration of this disease is still lacking. Also, due to the potent immunosuppressive properties of the agents used in the up-front treatment, for example, the purine nucleoside analogues, we have witnessed an increase in the incidence of opportunistic infections, with progressive multifocal leukoencephalopathy being one of the most serious. The goal of this review is to summarize the spectrum of neurologic derangements linked to chronic lymphocytic leukemia and to raise clinicians' awareness to recognize the possibility of such associations.

Chronic lymphocytic leukemia with central nervous system involvement: report of two cases with a comprehensive literature review

Central nervous system (CNS) involvement is a rare complication of chronic lymphocytic leukemia (CLL) with varied outcomes. We contribute two additional cases of CLL with CNS involvement. The clinical course and response to treatment are described. All 78 previously reported cases of CLL with CNS involvement are presented in this comprehensive review of the literature. CNS involvement of CLL is a rare complication that does not seem to correlate with any evident risk factors. Resolution of CNS symptoms can often be accomplished with intrathecal chemotherapy or irradiation. Early detection and treatment may result in better outcomes in this rare complication.

[Follicular dural lymphoma. Case report]

A case of a meningeal B-cell lymphoma is described. A 48-year-old man presented with an episode of grand mal seizure following a brain injury. An initial diagnosis of extradural hematoma was made based on the results of the cerebral computerized tomography scan. Magnetic resonance images demonstrated an enhanced mass with a dural tail attached to the meningeal layer of the temporal bone, suggesting a meningioma "en plaque". The mass was surgically excised. Tumoral removal was subcomplete (Simpson 2). Operative inspection also suggested a meningioma, but histological analysis and electron microscopy revealed a grade IV follicular B-cell lymphoma. Biological studies were normal. An extensive workup found an external iliac adenopathy with several osseous locations on PET. The patient underwent chemotherapy and radiotherapy. Three years after the first symptoms appeared, the patient is alive and free of symptoms. The clinicopathological features and treatments were discussed.

Leukemia and the nervous system

Leukemia affects the central and peripheral nervous system. Neurologic complications are a consequence of direct leukemic infiltration, as occurs with leukemic meningitis, and due to complications of either antileukemic treatment (thrombocytopenic or disseminated intravascular coagulation-related intracranial hemorrhage, steroid myopathy, vinca alkaloid peripheral neuropathy) or immune compromise (Herpes zoster shingles or Aspergillus meningitis).

Leptomeningeal disease in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is the most common lymphoproliferative disorder in the western hemisphere, with an annual incidence of 3:100000. Commonly patients are asymptomatic but not rarely disease progression occurs in the setting of lymphadenopathy and extensive leukemic burden. Leptomeningeal involvement in patients with CLL is infrequent, with presenting symptoms of headache (23%), acute or chronic changes in mental status (28%), cranial nerve abnormalities (54%) including optic neuropathy (28%), weakness of lower extremities (23%) and cerebellar signs (18%). In this report, we discuss a CLL patient with leptomeningeal involvement, who presented with neurological symptoms as the first clinical sign, and a diagnosis of leptomeningeal was made based on CSF cytology and flow cytometry. Treatment consisted of radiation therapy and intrathecal chemotherapy with arabinoside-cytosine and systemic chemotherapy. On the basis of this patient-report together with 37 other previously reported cases, the clinical characteristics together with treatment options and outcome of leptomeningeal involvement in CLL are reviewed. Our case together with data from the literature indicate that a timely diagnosis and intensive treatment of leptomeningeal disease of CLL may lead to longstanding and complete resolution of neurological symptoms.

Low-grade follicular lymphoma in the dura: Rare mimic of meningioma

Lymphomas rarely present as a localized mass within the dura. We report a case of a 72-year-old woman, normally fit and well, who presented with a sudden episode of grand mal seizure. Imaging studies showed an extra-axial mass arising from the dura, with radiologic features characteristic of a meningioma. The mass was surgically excised, and the histologic features were of a grade 1 follicular lymphoma. Analysis using fluorescent in situ hybridization (FISH) demonstrated t(14:18) translocation. A bone marrow aspirate showed focal infiltration of lumbar vertebra by low-grade follicular lymphoma. Intracranial meningeal involvement by non-Hodgkin lymphoma usually occurs in the form of diffuse leptomeningeal spread. It is seen in high-grade lymphomas, often in association with widespread systemic disease. The majority of cases of dural lymphomas reported in the literature have been primary mucosa-associated lymphoid tissue (MALT)-type lymphomas. Most of these presented as localized dural masses mimicking meningiomas. Low-grade follicular lymphoma, either primary or secondarily involving the dura, appears to be an exceedingly rare occurrence.

Excellent response of chemotherapy-resistant B-cell-type chronic lymphocytic leukemia with meningeal involvement to rituximab

A 70-year-old woman was diagnosed with B-cell-type chronic lymphocytic leukemia (B-CLL) in May 2001. Initial white blood cell (WBC) count was 37 x 10(9)/l and most of the cells were mature small lymphocytes. Surface antigen analysis of these lymphocytes revealed positive reactions for CD19, 20, 25, 5, and lambda-light chain. Despite her Rai stage-0 status, various treatments were ineffective, including cyclophosphamide; fludarabine; 6-mercaptopurine; a combination of vincristine, cyclophosphamide, prednisolone, and adriamycin; and etoposide. Her WBC count increased, ranging from 150 to 450 x 10(9)/l, with marked splenomegaly, and symptoms of meningitis, such as headache, ophthalmalgia, hearing disturbance, and abnormal behavior, being manifested. The WBC count in the cerebrospinal fluid was elevated to 134/microl. The surface phenotype of these cells was identical to that of circulating lymphocytes, indicating meningeal involvement of leukemia, a rare complication in B-CLL. At the time of this WBC elevation, 24% of circulating lymphocytes had prominent nucleoli, indicating progression of the disease to CLL/prolymphocytic leukemia. Her symptoms disappeared after repeated intrathecal injections of methotrexate and dexamethazone. After four courses of treatment of the refractory B-CLL with rituximab, an anti-CD20 monoclonal antibody, the WBC count returned to normal levels and the splenomegaly disappeared. She is currently well, with sustained remission, as of April 2004.

Leukemic and lymphomatous meningitis: incidence, prognosis and treatment

Neoplastic meningitis (NM) is a common problem in neuro-oncology occurring in approximately 5% of all patients with cancer. Notwithstanding frequent focal signs and symptoms in NM, NM is a disease affecting the entire neuraxis and therefore staging and treatment need encompass all cerebrospinal fluid (CSF) compartments. Central nervous system (CNS) staging of NM includes contrast enhanced cranial computerized tomography (CE-CT) or magnetic resonance imaging (MR-Gd), contrast enhanced spine magnetic resonance imaging (MR-S) or computerized tomographic myelography (CT-M) and radionuclide CSF flow study (FS). Treatment of NM involves involved-field radiotherapy of bulky or symptomatic disease sites and intra-CSF drug therapy. The inclusion of concomitant systemic therapy may benefit patients with NM and may obviate the need for intra-CSF chemotherapy. At present, intra-CSF drug therapy is confined to three chemotherapeutic agents (i.e. methotrexate, cytosine arabinoside and thio-TEPA) administered by a variety of schedules either by intralumbar or intraventricular drug delivery. Although treatment of NM is palliative with an expected median patient survival of 4 to 6 months, it often affords stabilization and protection from further neurologic deterioration in patients with NM. In patients with leukemia or lymphoma, prophylaxis of the CNS is used (utilizing a combination of high-dose systemic chemotherapy and intra-CSF chemotherapy) for patients at high risk as defined by specific tumor-related laboratory markers. Using such a risk-stratified approach, the late occurrence of CNS relapse has decreased dramatically attesting to the value of CNS prophylaxis.

Sustained visual recovery after treatment with intrathecal methotrexate in a case of optic neuropathy caused by chronic lymphocytic leukemia

A 68-year-old woman with chronic lymphocytic leukemia (CLL) had acute optic neuropathy associated with cerebrospinal fluid evidence of meningeal spread of CLL. There was no evidence of a hematologic relapse. After undergoing four weekly doses of intrathecal methotrexate, vision improved dramatically and spinal fluid became normal. Four years later, she has near normal vision in the affected eye and remains in hematologic remission. This is the first reported case of successful treatment of optic neuropathy in CLL with intrathecal methotrexate alone.

Leukemic leptomeningeal involvement in stage 0 and stage 1 chronic lymphocytic leukemia

Central nervous system (CNS) involvement in early (Rai Stage 0 and Stage 1) chronic lymphocytic leukemia (CLL) is rare, with only five cases reported. We present the sixth reported case, a 77-year-old male with a 4 year history of Stage 0 CLL who presented with sudden onset of diplopia and headache. Workup revealed a leukemic involvement of his CNS and he responded well to treatment with intrathecal (IT) methotrexate. After his third IT treatment, he developed a change in his mental status, consistent with a chemotherapy induced encephalopathy, which was effectively treated with IT hydrocortisone. In addition to the case presentation, we review the previously reported cases in an effort to determine any characteristics common among the Stage 0/1 CLL patients with reported CNS involvement.

Chronic lymphocytic leukaemia presenting with central nervous system involvement

A 68-year-old man presented with hemiparesis, lymphocytosis, and cerebral lesions on MRI. Flow cytometry of blood, bone marrow and cerebrospinal fluid showed B-CLL lymphocytes with bright CD20 expression, sIg, and absence of CD23 antigen. Fluorescence in situ hybridisation showed trisomy 12 in 50% of analysed peripheral mononuclear cells. The patient died 6 months after the diagnosis. Rapidly progressive and fatal course of the disease was consistent with known bad prognostic significance of CD20 bright expression and trisomy 12.

Chronic lymphocytic leukaemia with symptomatic diffuse central nervous system infiltration responding to therapy with systemic fludarabine

B-cell chronic lymphocytic leukaemia is an indolent disease characterized by the insidious accumulation of small mature-appearing lymphocytes in the peripheral blood, bone marrow and lymphoid tissues. Direct symptomatic invasion of the central nervous system is exceedingly rare and, to our knowledge, only three cases histologically confirmed as true chronic lymphocytic leukaemia have been reported in the literature. We describe the first case of early Rai stage B-cell chronic lymphocytic leukaemia presenting with symptomatic infiltration of the brain and spinal cord which could be demonstrated radiographically by magnetic resonance imaging. The diagnosis was confirmed by examination of peripheral blood, cerebrospinal fluid, brain and bone marrow biopsies, both morphologically and immunophenotypically by means of flow cytometric analysis. The patient demonstrated a complete response to therapy with standard-dose systemic fludarabine and remains in complete remission 6 months after completion of therapy.

Leptomeningeal involvement in chronic lymphocytic leukemia

PURPOSE

This review and case report address the rare complication of leptomeningeal involvement in patients with chronic lymphocytic leukemia.

OVERVIEW

Chronic lymphocytic leukemia is the most common form of leukemia, with more than 200,000 cases reported in the past 20 years. An uncommon complication of the disorder is central nervous system invasion. To date, only 21 cases have been reported, and their presenting symptoms have been heterogeneous and often nonspecific, including headache, cranial nerve abnormalities, confusion, ataxia, nausea, vomiting, and fever. The diagnosis is confirmed by the presence of a clonal population of lymphocytes in the cerebrospinal fluid. Treatment is either intrathecal or intraventricular chemotherapy with adjuvant radiation therapy or radiation alone. Prognosis is improved by prompt and aggressive therapy. In this case report, a 61-year-old man developed severe ataxia, vertigo, and occipital headaches 4 weeks after diagnosis with otherwise asymptomatic chronic lymphocytic leukemia. After treatment with both radiation to the head and neck and intrathecal methotrexate the patient achieved complete symptom resolution. Thus far, no additional systemic cytotoxic chemotherapy has been necessary.

CLINICAL IMPLICATIONS

Because central nervous system invasion is uncommon in chronic lymphocytic leukemia, it may go undiagnosed and under-reported. Providers of patients with this disease need to be aware of possible central nervous system invasion when patients present with cranial nerve signs or symptoms and/or nonspecific neurologic manifestations. Early identification and prompt central nervous system-directed chemotherapy can affect morbidity and quality of life positively.

Meningeal metastases: clinical aspects and diagnosis

The authors review the clinical and diagnostic aspects involved in leptomeningeal disease due to solid tumours, leukaemias and lymphomas. The importance of the combination of clinical findings with cerebral spinal fluid (CSF) examination and imaging studies in making an early diagnosis is underlined. The raising prevalence of this complication of systemic cancer deserves specific attention on the part of neurologists involved in consultation liason with general medicine and oncology.

Chronic lymphocytic leukaemia with cerebral infiltration

Central nervous system (CNS) involvement is an extremely rare complication of chronic lymphocytic leukaemia (CLL). This report describes a case of stable, early stage CLL who developed histologically documented cerebral infiltration two years after the diagnosis and responded to cranial radiotherapy.

Leukemic meningitis in B-cell prolymphocytic leukemia. A clinical, pathologic, and ultrastructural case study and a review of the literature

BACKGROUND

Leukemic meningitis is rare in B-chronic lymphocytic leukemia (CLL) and B-prolymphocytic leukemia (PLL); a MEDLINE search for reports published 1960 and after disclosed only nine prior reports. A patient with stable Rai Stage II CLL/PL developed mental status changes. Lumbar puncture revealed a lymphocytic pleocytosis with prolymphocytes containing intracytoplasmic inclusions.

METHODS

The patient's cerebrospinal fluid lymphocyte population was analyzed by immunophenotyping and electron microscopy.

RESULTS

The studies revealed a clonal population of B prolymphocytes, with typical immunophenotypic and ultrastructural characteristics. The patient was treated with intrathecal chemotherapy with eventual resolution of the cerebrospinal fluid pleocytosis and return to his normal neurologic status. Prior studies also have revealed the efficacy of intrathecal chemotherapy.

CONCLUSION

Leukemic meningitis in CLL or PLL is responsive to treatment with intrathecal chemotherapy.

Leukemic meningitis in a patient with splenic lymphoma with villous lymphocytes (SLVL). Meningitis as a possible initial manifestation of SLVL

BACKGROUND

Splenic lymphoma with villous lymphocytes (SLVL) is a low grade, non-Hodgkin's lymphoma with a stable or slowly progressive clinical course. To the authors' knowledge, central nervous system involvement has not been described previously in patients with SLVL.

METHODS

Morphologic, immunocytochemical, and immunohistochemical analyses were conducted to determine the nature of villous lymphocytes in the peripheral blood, spleen, and cerebrospinal fluid (CSF) of a patient with massive splenomegaly.

RESULTS

A diagnosis of SLVL was made, based on tartrate-resistant acid phosphatase-negative peripheral villous lymphocytosis with CD19+, CD20+, HLA-DR+ phenotypes, and the involvement of spleen white pulp with these cells. Mononuclear cells in the CSF showed the same morphologic and immunocytochemical features seen in the villous lymphocytes in the peripheral blood and spleen. Splenectomy and intrathecal chemotherapy were successful in clearing leukemic cells from the CSF.

CONCLUSION

In this patient with SLVL in whom leukemic meningitis developed, meningitis was found to be a possible initial manifestation of SLVL.

Immunophenotyping of cytologic specimens by flow cytometry

Immunophenotyping by flow cytometry is well established as an ancillary technique in the diagnosis of hematopoietic neoplasms. However, flow cytometry is rarely performed on cytologic specimens because most cytologist are more comfortable with direct microscopy and believe that there is inadequate cellularity for analysis. Paradoxically, cytologic material is usually cell suspensions making it ideal for flow cytometry. In order to evaluate the usefulness of immunophenotyping cytologic specimens by flow cytometry, we retrospectively reviewed all cytologic specimens submitted to our flow cytometry unit from 1988 to 1991. Thirty-one cerebrospinal fluid specimens were analyzed. There were inadequate cells for analysis in 15 cases. Five showed a monoclonal proliferation; 11 were nondiagnostic. A range (r) of one to six cell surface markers were performed. Thirty-two body cavity fluids were analyzed: 7 peritoneal, 19 pleural, 2 pericardial, and 4 bronchoalveolar lavage. There were cells to analyze in all cases. Seven had a monoclonal proliferation; 25 were nondiagnostic (r = 4-21 markers performed). One hundred eighteen fine needle aspirates (FNA) were reviewed; 58 FNA were radiologically guided, 60 were superficial lesions. There were inadequate cells for analysis in two cases. Sixty-one demonstrated a monoclonal proliferation; 55 were nondiagnostic (r = 1-22 markers performed). We conclude that immunophenotyping by flow cytometry is of limited value for cerebrospinal fluid analysis and that knowledge of previous immunophenotyping studies is essential for correct analysis; analysis of body cavity fluids is easily performed but less often demonstrates a monoclonal proliferation. Immunophenotyping by flow cytometry is a valuable adjunctive technique for FNA and yields adequate cells for analysis.

Hyperventilation as the initial manifestation of lymphomatous meningitis

We present the case of a 57 year old man who developed a B-cell lymphoma which involved his lymph nodes, liver, spleen, bone marrow, and peripheral blood. Shortly after attaining a complete remission with chemotherapy, the patient developed profound hyperventilation with no apparent cardiac or pulmonary cause. After one month, the patient developed a 7th nerve palsy and a subsequent work-up demonstrated that he had lymphomatous meningitis. The hyperventilation resolved completely with intrathecal chemotherapy, although the patient eventually died of widely disseminated lymphoma.

Longterm meningeal involvement as the only clinical manifestation of low grade malignant non-Hodgkin's lymphoma

We present the case of a 56-year-old man who developed-at the age of 46-paraesthesia and numbness in the perianal region, the feet and lower legs accompanied by the presence of B-lymphocytes in the cerebrospinal fluid (CSF). Despite intensive work-up an explanation was not found until he developed hepato-splenomegaly ten years after the initial symptoms. Haematologic evaluation at that time disclosed a low-grade malignant B-cell lymphoma. Repeated CSF examination revealed 31 leukocytes/mm3, of which were mainly lymphocytes. These proved to be B-lymphocytes of monoclonal origin. These findings suggest that a leptomeningeal localisation of a low-grade malignant lymphoma had been present for ten years before systemic manifestation of the disease.

Flow cytometric surface light chain analysis of lymphocyte-rich effusions. A useful adjunct to cytologic diagnosis

The cytologic diagnoses in 49 body cavity fluids from 46 patients, of whom 30 had a clinical diagnosis of lymphoma or lymphatic leukemia, and 16 patients with benign inflammatory or reactive conditions, were compared to flow cytometric surface immunoglobulin light chain analysis (kappa-lambda analysis [KLA]). The results of both tests were correlated with clinical outcome and all available information from biopsy, autopsy, and additional cell marker studies. When the diagnoses by both cytologic analysis and KLA were in agreement (57.1% of cases), there were no false-negative or false-positive results. Overall, false-positive and false-negative rates were, respectively, 6.1% and 12.2% with cytologic study, and 4.1% and 4.1% with KLA. Sixteen samples were from patients with small lymphocytic lymphoma (CLL) and small cleaved lymphoma, which had a false-negative rate of 37.5% by cytologic study, and only 6.2% by KLA. There was one false-positive result by KLA among the benign effusions. These findings indicate that KLA is a powerful adjunct to the cytologic evaluation of lymphocyte-rich effusions, especially in cases of lymphoproliferative disorders characterized by small lymphocytes, in which the cytologic diagnosis is frequently difficult.