Fusion PET-CT imaging of neurolymphomatosis

Primary Central Nervous System Lymphoma With Diffuse Neurolymphomatosis Involving Multiple Cranial and Spinal Nerve Roots

Primary central nervous system lymphoma is an extranodal lymphoma originating in the brain, spinal cord, and leptomeninges, which rarely spreads outside the nervous system. Neurolymphomatosis is the term used to describe lymphomatous involvement of the cranial nerves (except optic nerve) and peripheral nerve roots or plexus. We report a case of a 23-year-old man presented with progressive weakness of all 4 limbs. F-FDG PET/CT revealed FDG-avid thickening along the multiple cranial nerve roots, spinal nerve roots, and brain parenchymal lesion. Core biopsy from the peripheral nerve root demonstrated the lymphomatous involvement.

Peripheral nervous system involvement in lymphomas

The peripheral nervous system may be involved at any stage in the course of lymphoproliferative diseases. The different underlying mechanisms include neurotoxicity secondary to chemotherapy, direct nerve infiltration (neurolymphomatosis), infections, immune-mediated, paraneoplastic or metabolic processes and nutritional deficiencies. Accordingly, the clinical features are heterogeneous and depend on the localization of the damage (ganglia, roots, plexi, and peripheral nerves) and on the involved structures (myelin, axon, and cell body). Some clinical findings, such a focal or diffuse involvement, symmetric or asymmetric pattern, presence of pain may point to the correct diagnosis. Besides a thorough medical history and neurological examination, neurophysiological studies, cerebrospinal fluid analysis, nerve biopsy (in selected patients with suspected lymphomatous infiltration) and neuroimaging techniques (magnetic resonance neurography and nerve ultrasound) may be crucial for a proper diagnostic workup.

Neurolymphomatosis of the Brachial Plexus and its Branches: Case Series and Literature Review

BACKGROUND

Neurolymphomatosis is a process of neoplastic endoneurial invasion, most strongly associated with non-Hodgkin's lymphoma. It must be distinguished from paraneoplastic, metabolic, nutritional and treatment-related causes of neuropathy that are common in this patient population.

METHODS

This brief case series illustrates the protean manifestations of neurolymphomatosis of the brachial plexus, ranging from focal distal mononeuropathy to multifocal brachial plexopathy, either as the index manifestation of lymphoma or as a complication of relapsing disease.

RESULTS

Prominent asymmetry, pain and nodular involvement on neuroimaging may help distinguish neurolymphomatosis from paraneoplastic immune demyelinating radiculoneuropathy. MR neurography criteria for the diagnosis of neurolymphomatosis include hyperintensity on T2 and STIR sequences, focal and diffuse nerve enlargement with fascicular disorganization and gadolinium enhancement. No specific anatomical distribution within the brachial plexus has, however, been found to be characteristic. Fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging is the imaging modality with the highest sensitivity for detection of nodal or extranodal spread in lymphoma.

CONCLUSIONS

Brachial plexus neuropathy in neurolymphomatosis is highly protean in its distribution, semiology and relation to lymphoma staging. Dedicated MRI and PET-CT imaging are leading diagnostic modalities.

Neurolymphomatosis: A Surreal Presentation of Lymphoma

Background:

Neurolymphomatosis is a neurologic complication poorly recognized by neurologists and oncologists and presents usually several months after successful treatment of systemic lymphoma. Other disorders that must be differentiated from these entities include peripheral-nerve or nerve root compression and paraneoplastic neuropathy.

Aim:

To describe the unusual occurrence of neurolymphomatosis in a patient of B-cell lymphoma.

Method:

Diagnosis was made by demonstration of enhancement of nerve roots on Magnetic Resonance Imaging of the brachial, lumbosacral plexus, peripheral nerves or by increased hyper-metabolic activity along the course of affected nerves on fluorodeoxyglucose positron emission tomography (FDG-PET).

Results and Conclusion:

MRI and PET-CT are imaging modalities of choice for evaluation of patients with lymphoma and suspected neural involvement. Treatment of neurolymphomatosis consists of focal radiotherapy and high-dose methotrexate therapy.

FDG PET-CT evaluation in neurolymphomatosis: imaging characteristics and clinical outcomes

Neurolymphomatosis (NL) often represents unidentified non-Hodgkin lymphoma relapses. Considering its severity, early detection and treatment are crucial. We outline one hospital's ¹⁸F-FDG-PET-CT imaging findings of NL, along with the patients' clinical characteristics. Clinical records and imaging findings of 19 NL patients, PET-CT diagnosed, were retrospectively reviewed. Patient data, FDG-PET-CT findings and the presence of coexisting diseases, especially CNS involvement, were documented. Available MRI and clinical data verified the findings. All cases had increased linear FDG uptake along anatomic nerve sites. CTs showed varying degrees of corresponding soft-tissue-thickening. Clinical correlations also contributed to the diagnosis. In 4/19 patients, lymphoma presented with NL, in 15/19 it appeared with disease recurrence/progression. In 9/19, clinical symptoms suggested neural involvement while 10/19 had nonspecific symptoms. Eleven died of lymphoma within 0.9 years of diagnosis despite directed-therapy. Eight, however, survived up to 7.82 years post-diagnosis. Whole-body FDG-PET-CT can assist in early NL diagnosis, possibly enhancing survival.

FDG PET/CT in Pediatric Neurolymphomatosis

An 8-year-old girl presented with back and leg pain and left arm and leg paresis. Lumbar puncture was suggestive of lymphocytic meningitis without identified organism. A second lumbar puncture demonstrated a large number of lymphoid B cells, with positive immunohistochemical staining for CD20 and CD25, proving the diagnosis of neurolymphomatosis. Brain and spine MRI demonstrated involvement of cervical and lumbosacral nerve roots. FDG PET/CT showed multiple bone metastases in addition to nerve involvement. Postchemotherapy FDG PET/CT demonstrated complete metabolic response.

Peripheral Nerve Lymphomatosis

Lymphoma involvement of peripheral nerves is rare and it may mimic benign neurogenic tumors or neuropraxic injury. This study presents three patterns of presentations in four patients with neurolymphomatous involvement of their peripheral nerves. We reviewed the clinical records of four patients who underwent exploratory brachial plexus surgery (n = 1), pronator tunnel decompression (n = 1) and peripheral nerve exploration (n = 2) and subsequently found to have neurolymphomatosis (NL). Histological diagnoses were diffuse large B-cell lymphoma (n = 3) and NK/T-cell lymphoma (n = 1). NL lacks pathognomonic clinical and imaging features that aid clinicians in diagnosis. Apart from a history of lymphoma, and high clinical index of suspicion, PET-CT scans appear to be a helpful adjunct in detecting high metabolic lesions occuring in situ or systemically. Intra-operative frozen section is helpful to detect round blue cells, before final cytological diagnosis.

An Extremely Rare Intersection: Neurolymphomatosis in a Patient with Burkitt Lymphoma Detected by 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography

Neurolymphomatosis (NL) is a rarely seen neurologic involvement of the systematic lymphoma. Its diagnosis is challenging, and requires biopsy. In cases where biopsy is not appropriate, 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) may aid in diagnosis. Here, we present a 54-year old male patient diagnosed with Burkitt lymphoma who underwent FDG-PET/CT in order to evaluate the treatment response after chemotherapy and radiotherapy. On viewing PET/CT images of the patient who complained of pain and weakness in his upper extremities after therapy, linear FDG uptake was observed in bilateral cervical 5 (C5), left cervical 6 (C6), bilateral cervical 7 (C7), and right lumbar 4 (L4) nerve roots. Magnetic resonance imaging (MRI) revealed dilation and thickening of nerve roots consisted with FDG uptake observed on PET/CT images. Since biopsy was not performed, histopathological diagnosis could not be established. However, overlapping of clinical, PET/CT, and MRI findings strongly suggested the presence of NL. As is the case of this patient, in cases with non-Hodgkin lymphoma, a combined evaluation of FDG-PET/CT and MRI modalities aid in the establishment of the diagnosis of NL.

Lymphoma relapse presenting as neurolymphomatosis

Neurolymphomatosis (NL) is a rare neurological manifestation of lymphoma characterized by malignant lymphoma cells infiltrating cranial or peripheral nerve, or their roots. We present the first reported Australian case of a patient whose initial presentation of relapsed mantle cell lymphoma was NL. Our case highlights that clinical and imaging findings of NL often mimic other neuropathies, and hence presents unique challenges that may lead to delayed diagnosis and management. We emphasize the importance of considering NL in the differential diagnosis and combining imaging with other diagnostic modalities such as lumbar puncture (LP) to aid in the diagnosis of NL particularly where there is acute neurological deterioration.

Neuropathies associated with lymphoma†

Neuropathy occurs with various manifestations as a consequence of lymphoma, and an understanding of the etiology is necessary for proper treatment. Advances in medical imaging have improved the detection of peripheral nerve involvement in lymphoma, yet tissue diagnosis is often equally important. The neoplastic involvement of the peripheral nervous system (PNS) in lymphoma can occur within the cerebrospinal fluid (CSF), inside the dura, or outside of the CSF space, affecting nerve root plexuses and peripheral nerves. The infiltration of either cranial or peripheral nerves in lymphoma is termed neurolymphomatosis (NL). These infiltrations can occur as mononeuropathy, multifocal neuropathy, symmetric neuropathies, or plexopathies. In rare cases, intravascular lymphoma (IL) can affect the PNS and an even rarer condition is the combination of NL and IL. Immune-mediated and paraneoplastic neuropathies are important considerations when treating patients with lymphoma. Demyelinating neuropathies, such as Guillain-Barré syndrome and chronic inflammatory demyelinating polyradiculoneuropathy, occur more frequently in non-Hodgkin's lymphoma than in Hodgkin's disease. Paraproteinemic neuropathies can be associated with lymphoma and paraneoplastic neuropathies are rare. While the treatment of lymphomas has improved, a knowledge of neurotoxic, radiotherapy, neoplastic, immune-mediated and paraneoplastic effects are important for patient care.

Secondary neurolymphomatosis detected by whole-body diffusion-weighted magnetic resonance imaging: a case report

Neurolymphomatosis (NL) is a rare clinical entity defined as peripheral nervous system infiltration by lymphoma. The diagnosis is difficult and often elusive. Whole-body diffusion-weighted magnetic resonance imaging (DW MRI) was developed to enhance the detection of vaguely delineated tumors. Here, we describe the case of a 71-year-old male with secondary NL of diffuse large B-cell lymphoma (DLBCL) that was successfully detected by whole-body DW MRI. The patient was diagnosed with DLBCL extending from the ethmoidal sinus to the nasal cavity, orbital cavity, and anterior cranial fossa. Although he was administered R-THP-COP chemotherapy and the tumor remarkably decreased in size, he developed painful paresthesia and weakness in the left upper and bilateral lower extremities during treatment. Because lymphoma cells were detected in his spinal fluid, high-dose methotrexate (MTX) and weekly intrathecal MTX and cytarabine injections were administered. Test results for lymphoma cells in the spinal fluid became negative ; however, the neurological disorders progressed. Whole-body DW MRI was performed as whole-body screening and could localize NL at the left cervical and bilateral lumbar nerve roots. Both cervical spine plain MRI and enhanced computed tomography performed around the same time could not detect the cervical lesion. Our case report suggests that whole-body DW MRI is a useful diagnostic imaging procedure, especially as whole-body screening in facilities where PET/CT is not available.

Bilateral trigeminal nerve recurrence of non-hodgkin lymphoma revealed with FDG PET/CT

Bilateral trigeminal nerve involvement is a rare presentation of Non-Hodgkin lymphoma (NHL). The trigeminal nerve, also called the fifth cranial nerve, leaves the brainstem and exits the base of the skull to supply sensation to the face. In this case, we present a case of a 63-year-old male patient with a history of NHL and a more recent history of headache and trigeminal neuralgia. The patient underwent PET/CT demonstrating bilateral increased FDG uptake in trigeminal nerves.

Four rare extranodal sites seen on FDG PET/CT in a single patient of disseminated lymphoma

Extranodal disease refers to lymphomatous infiltration of anatomic sites other than lymph nodes. With the advent of FDG PET/CT for staging, rare sites of extranodal disease have been documented. We report a case of Non- Hodgkin's lymphoma with four rare extranodal sites, namely adrenal, peripheral nerves, pancreas and prostate, in the same patient, detected on FDG PET/CT imaging.

Malignant cell infiltration in the peripheral nervous system

The peripheral nervous system can be affected by malignancies involving different mechanisms. Neoplastic nerve lesion by compression, invasion, and infiltration is rare and occurs in particular in leukemia (neuroleukemiosis) and lymphoma (neurolymphomatosis). Its occurrence is much rarer in cancer, and even less so in sarcoma. The neoplastic infiltration of peripheral nerves by solid tumors is characterized by specific topographical sites such as the base of the skull, the ear, nose and throat region, and the cervico-brachial plexus as well as the lumbar and sacral plexus. Rarely malignant invasion affects the cranial nerves of the face where it can spread centripetally. Autonomic nerves and ganglia can also be affected. The retrograde spread of cancer in nerves is a bad prognostic sign. The clinical diagnosis is determined by tumor type, the pattern of involvement, and often pain.

Neurolymphomatosis diagnosed by (18)F-FDG PET-CT

Neurolymphomatosis is defined as infiltration of the nervous system by hematological malignancy and is difficult to diagnose. We report a case of a 57-year-old man, treated for small B-cell non-Hodgkin lymphoma, presenting with sensorimotor impairment of the lower limbs, which started 6 years after diagnosis. He was treated with chemotherapy, after which, the symptoms disappeared. After 7 months, he developed sensorimotor impairment of both upper limbs. MRI of the brachial plexus showed no abnormalities. F-FDG PET-CT showed increased uptake at the brachial plexus and nerves, suggesting neurolymphomatosis. Confirmatory biopsy revealed conversion of the malignancy to diffuse large B-cell lymphoma.

F-18 FDG PET/CT for detection of malignant involvement of peripheral nerves: case series and literature review

PURPOSE

To evaluate the role of positron emission tomography plus computed tomography (PET/CT) scans in detecting malignant involvement of the peripheral nerves (PNs).

MATERIAL AND METHODS

We retrospectively reviewed medical records of all PET/CT studies performed at The University of Texas MD Anderson Cancer Center between 2003 and 2009, and selected patients in whom F-18 fluorodeoxyglucose (FDG) PET/CT findings were suspicious for malignant involvement of the PNs. We identified 26 cases of suspected tumorous involvement of the PNs that was subsequently confirmed by either biopsy or clinical follow-up. We evaluated the value of PET/CT in diagnosing malignant involvement of the PNs.

RESULTS

Of the 26 patients, 12 had lymphoma, 10 had breast cancer, 2 had lung cancer, 1 had colon cancer, and 1 had melanoma. In 21 patients, magnetic resonance imaging (MRI) was performed, either for follow-up of the PET/CT finding or to find an explanation for symptoms. MRI confirmed the presence of disease in only 9 patients, was interpreted as normal in 7 patients, and was inconclusive in 5 patients. FDG PET/CT was able to differentiate an active tumor from post-treatment fibrosis and could assess response to therapy with a high degree of confidence.

CONCLUSIONS

Our results indicate that FDG PET/CT is helpful in diagnosing malignant involvement of the PNs, especially when findings from anatomic imaging (MRI or CT) are negative. In cases of known treated malignancy involving the PNs, follow-up by PET/CT has the advantage of high sensitivity for local recurrence.

Neurolymphomatosis: an International Primary CNS Lymphoma Collaborative Group report

Neurolymphomatosis (NL) is a rare clinical entity. The International Primary CNS Lymphoma Collaborative Group retrospectively analyzed 50 patients assembled from 12 centers in 5 countries over a 16-year period. NL was related to non-Hodgkin lymphoma in 90% and to acute leukemia in 10%. It occurred as the initial manifestation of malignancy in 26% of cases. The affected neural structures included peripheral nerves (60%), spinal nerve roots (48%), cranial nerves (46%), and plexus (40%) with multiple site involvement in 58%. Imaging studies often suggested the diagnosis with 77% positive magnetic resonance imaging, and 84% (16 of 19) positive computed tomography-positron emission tomography studies. Cerebrospinal fluid cytology was positive in 40%, and nerve biopsy confirmed the diagnosis in 23 of 26 (88%). Treatment in 47 patients included systemic chemotherapy (70%), intra-cerebrospinal fluid chemotherapy (49%), and radiotherapy (34%). Response to treatment was observed in 46%. The median overall survival was 10 months, with 12- and 36-month survival proportions of 46% and 24%, respectively. NL is a challenging diagnosis, but contemporary imaging techniques frequently detect the relevant neural invasion. An aggressive multimodality therapy can prevent neurologic deterioration and is associated with a prolonged survival in a subset of patients.

[Neurolymphomatosis: diagnosis of extension and assessment of response to treatment with PET-CT]

Neurolymphomatosis is a rare neurological manifestation of non-Hodgkin's lymphoma (NHL) and it may be its first and sole manifestation. Diagnosis is often difficult and nerve biopsy is generally required. However, this it is not always possible to perform or is not conclusive. We present the case of a 66-year-old woman diagnosed with giant B-cell NHL. After 6 cycles of chemotherapy, imaging and molecular biology techniques showed complete remission. At four months after treatment, the patient complained of low back pain of radicular distribution. CT and MRI imaging showed signs of lymphoproliferative activity of L5 and also lesions to thoracic nerve roots. A PET-CT was requested in order to complete the diagnosis and plan the treatment. Imaging confirmed the presence of tumor recurrence with neurolymphomatosis and also indicated lesions on the chest and abdominal level. Thus, it was decided to start a new line of chemotherapy, without performing the histological study through biopsy. This case illustrates the important role played by PET-CT imaging in neurolymphomatosis diagnosis. This technique can help the patient avoid more aggressive procedures, such as a biopsy, and can also be useful in the follow-up and assessment of the treatment response to NHL-diagnosed patients.

Neuroleukemiosis: case report of leukemic nerve infiltration in acute lymphoblastic leukemia

We describe a patient in remission from acute lymphoblastic leukemia who developed a painless common peroneal neuropathy. Magnetic resonance imaging (MRI) revealed nerve thickening and enhancement, while a positron emission tomography (PET) scan demonstrated increased fluorodeoxyglucose uptake in a large segment of the neurovascular bundle, suggesting peripheral nerve infiltration. Both findings resolved following treatment with chemotherapy that crossed the blood-nerve barrier. In selected patients presenting with peripheral neuropathy, MRI and PET scan can be helpful in the diagnosis of peripheral nerve infiltration.

Peripheral nervous system involvement in patients with cancer

Involvement of the peripheral nervous system (PNS) is common in patients with cancer and any part, including motor neurons, sensory ganglia, nerve roots, plexuses, cranial and peripheral nerves, and neuromuscular junctions, can be affected. Different mechanisms can initiate damage associated with cancer-related PNS disorders. These include tumour infiltration, toxicity of treatments, metabolic and nutritional perturbations, cachexia, virus infections, and paraneoplastic neurological syndromes. The type of cancer, lymphoma, or solid tumour is a further determinant of a PNS disorder. In this Review we discuss the different causes and mechanisms of disorders of the PNS in patients with cancer and we will focus on their assessment and diagnosis.

Rare pathological variants and presentations of primary central nervous system lymphomas

Primary central nervous system lymphoma (PCNSL) is a rare form of primary brain neoplasm, accounting for less than 3% of all primary brain tumors. Ninety percent of cases involve a large B-cell lymphoma that presents as a homogeneously enhancing lesion or lesions, typically deep-seated in the brain parenchyma. The authors describe unusual pathological forms of PCNSLs, including low-grade, T-cell, and Burkitt types, and also rare presentations such as neurolymphomatosis and pituitary lymphomas.

Metastases to the peripheral nervous system

Cancer metastasis can affect any part of the nervous system. When the peripheral nervous system is involved, the usual targets are cranial nerves, nerve roots and plexi. However, peripheral nerves and muscles can also be affected by compression or infiltration of neoplastic cells. This review focuses in the diagnosis and treatment of metastatic complications of cancer involving plexi, peripheral nerves and muscles.

Clinical value of combined positron emission tomography/computed tomography imaging in the interpretation of 2-deoxy-2-[F-18]fluoro-D-glucose-positron emission tomography studies in cancer patients

BACKGROUND

Positron emission tomography (PET)/computed tomography (CT) is a new imaging modality that provides exact coregistration of anatomic and metabolic data. We have investigated to what degree this new technique might affect the interpretation of PET images in a nonselected group of consecutive cancer patients, reflecting routine condition in a busy cancer center.

METHODS

Whole-body 2-deoxy-2-[F-18]fluoro-D-glucose (FDG)-PET and PET/CT fusion image sets were compared in 100 consecutive, nonselected patients: 21 with head and neck cancer, 39 with chest malignancies, and 40 with malignancies of the abdomen and pelvis. All studies were performed for primary staging or evaluation of therapy and were interpreted by two nuclear medicine physicians also trained in radiology. Areas of abnormal FDG uptake were identified on PET and graded as likely benign, equivocal, or likely malignant. Positron emission tomography/computed tomography fusion images were then made available, and the initial findings were amended if necessary.

RESULTS

One hundred sixty-six areas with abnormal FDG uptake were identified. Based on PET alone, 51 sites were considered equivocal for malignancy. With PET/CT, the number of equivocal lesions decreased to 24. This difference is more marked in the head and neck as well as the abdomen and pelvis. When the equivocal sites were included in the analysis and grouped with the malignant sites, positive predictive value (PPV) of PET/CT was 89% compared with 75% for PET (p = 0.04).

CONCLUSION

Combined PET/CT results in increased reader confidence and 53% fewer equivocal readings, as well as improved PPV compared with PET alone.

Unusual Variants of Primary Central Nervous System Lymphoma

Rare variants of primary central nervous system lymphoma (PCNSL) include unusual sites of presentation (eg, neurolymphomatosis and primary leptomeningeal lymphoma) and uncommon pathologic entities. Neurolymphomatosis involves peripheral nerves and nerve roots in addition to systemic and central nervous system (CNS) sites. Diagnosis requires a high index of suspicion, and treatment incorporates the principles of therapy for systemic and CNS lymphoma. Primary leptomeningeal lymphoma can present with symptoms of raised intracranial pressure or cranial or spinal polyradiculopathies. Diagnosis can be made by examining cerebrospinal fluid and incorporating immunophenotyping and molecular pathology techniques. Treatment options include irradiation and intrathecal or systemic chemotherapy. The features of PCNSL of T-cell origin and indolent B-cell PCNSL also are discussed.

Assessment of neurolymphomatosis by brachial plexus biopsy and PET/CT. Report of a case

OBJECTIVE

To report a biopsy-proven neurolymphomatosis in a young woman with previous non-Hodgkin's lymphoma (NHL) of uterine cervix.

PATIENT

The patient presented with a painful brachial plexopathy and developed multiple cranial and spinal nerve palsies.

METHODS AND RESULTS

The diagnosis was achieved by an open brachial plexus biopsy. A PET/CT study was used to assess the full extent of the disease and showed involvement of additional cranial nerves and spinal nerve roots. A complete although short lasting clinical and radiological response was achieved by means of systemic high dose methotrexate treatment combined with rituximab and intra-CSF injections of cytarabine.

Lymphoma and peripheral neuropathy: a clinical review

Lymphoma occasionally affects the peripheral nervous system. When it does, the diagnosis can be elusive since many patients present without known lymphoma. Most peripheral nerve complications are due to non-Hodgkin's lymphoma (NHL), which infiltrates nerves causing axonal damage. This disorder can affect nerve roots and cranial nerves, often associated with lymphomatous meningitis. NHL may also infiltrate peripheral nerves and cause plexopathy, mononeuropathy, or generalized neuropathy. These neuropathies may resemble an asymmetric mononeuropathy multiplex or a generalized disorder such as chronic inflammatory demyelinating polyradiculoneuropathy. When NHL infiltrates diffusely, the term neurolymphomatosis is used. Hodgkin's lymphoma (HL), by contrast, rarely infiltrates nerves. More often, HL causes immunological disorders of the peripheral nervous system such as inflammatory plexopathy or Guillain-Barré syndrome. Other rare lymphomas such as intravascular lymphoma and Waldenstrom's macroglobulinemia can also affect peripheral nerves in specific ways. In addition, other malignant and nonmalignant lymphoproliferative disorders enter into the differential diagnosis of lymphomatous neuropathy. This review discusses the multiple peripheral nerve presentations of lymphoma from the clinician's point of view and provides a guide to the evaluation and diagnosis of these uncommon, challenging disorders.

PET-CT imaging of combined brachial and lumbosacral neurolymphomatosis

Neurolymphomatosis is a rare manifestation of progressive non-Hodgkin's lymphoma. A 44-yr-old man with diffuse large B-cell lymphoma presented with unilateral progressive peripheral sensorimotor neuropathy after the 7th cycle of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone) therapy. No pathology in the nervous system was evident by computerized tomography (CT), magnetic resonance imaging (MRI) of the head, spinal axis and plexuses and by repeated analysis of cerebrospinal fluid. However, the hybrid modality of positron emission tomography (PET) of fluorinated deoxyglucose (FDG) combined with CT scan (PET-CT) showed unilateral involvement of both the brachial and lumbosacral nervous plexuses. A complete recovery of neurological manifestations and normalization of PET-CT followed intensive chemotherapy with autologous stem cell transplantation. The diagnosis and localization of neurolymphomatosis may be supported by PET-CT imaging.