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 »  Introduction
 »  Case report
 »  Discussion
 »  Conclusion
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Year : 1999  |  Volume : 47  |  Issue : 3  |  Page : 234-7

Solitary plasmacytoma presenting as peripheral neuropathy : a case report.

Department of Neurology, Grant Medical College and J.J. Group of Hospitals, Mumbai, 400008, India.

Correspondence Address:
Department of Neurology, Grant Medical College and J.J. Group of Hospitals, Mumbai, 400008, India.

  »  Abstract

We report a 26 year old woman presenting with a chronic predominantly motor radiculoneuropathy. A biopsy proven solitary lytic plasmacytoma was detected in the left sixth rib. Serum immunoelectrophoresis revealed 'M' band (IgG, l light chain). Excision of the plasmacytoma resulted in gradual but steady recovery. We suggest that all patients with 'cryptogenic' polyneuropathy be investigated for this potentially treatable condition. A high index of suspicion assists the organization of appropriate diagnostic investigations.

How to cite this article:
Mankodi A K, Rao C V, Katrak S M. Solitary plasmacytoma presenting as peripheral neuropathy : a case report. Neurol India 1999;47:234

How to cite this URL:
Mankodi A K, Rao C V, Katrak S M. Solitary plasmacytoma presenting as peripheral neuropathy : a case report. Neurol India [serial online] 1999 [cited 2023 Mar 31];47:234. Available from: https://www.neurologyindia.com/text.asp?1999/47/3/234/1608

   »   Introduction Top

The occurrence of a solitary plasmacytoma and peripheral neuropathy is a rare but intriguing association. A solitary plasmacytoma is usually a localized form of multiple myeloma. The neuropathy presents quite early in the natural history of this malignancy almost a decade or two before the patient becomes symptomatic for myeloma. If not suspected, the diagnosis may be entirely missed, as myeloma can be detected only by performing certain specific investigations. Once the diagnosis is made the patient usually improves with the therapy. Therefore it would be prudent to investigate all patients with `cryptogenic's polyneuropathy for myeloma. A case with solitary plasmacytoma and a peripheral neuropathy is presented to emphasize this point.

   »   Case report Top

A 26-year old woman presented with a progressive four-month history of symmetrical distal limb weakness. The lower limbs were more affected. There were no symptoms suggestive of bulbar, sphincter, sensory or autonomic dysfunction. There was no history of diabetes, exposure to toxins, peripheral neuropathy in family members, joint or bone pains, myalgia, and loss of weight or appetite. Examination revealed an asthenic individual with normal vital parameters. There was no evident pallor, lymphadenopathy, abnormal skin pigmentation, thickened nerves, bone tenderness or visceromegaly. She had symmetrical wasting of small muscles of hands and feet. The motor power was MRC grade 0/5 distally and 3/5 proximally in lower limbs and 4/5 in the upper limbs. There was symmetrical hypoaesthesia for touch, pain, temperature, and position and vibration sense below the level of both knees. All deep tendon reflexes were absent. Plantar response could not be elicited because of motor weakness. Investigations showed normal haemoglobin, erythrocyte sedimentation rate (ESR), fasting and postprandial blood sugar, liver and renal profile. HIV-ELISA was negative. Urine examination for Bence-Jones proteins and immunoelectrophoresis was negative. Serum protein electrophoresis was normal, but a non-quantifiable M band (IgG, l light chain) was seen on immunoelectrophoresis. X-rays of the skull, spine, pelvis and scapula were normal. However, the X-ray chest showed an osteolytic lesion in the left sixth rib [Figure 1]. Cerebrospinal fluid (CSF) examination revealed elevated proteins (120mg%) with normal cell count and glucose content. Bone marrow aspiration and trephine biopsy examination was normal. Electromyography (EMG) showed total deneravation in the muscles of feet and legs and chronic partial denervation with reinnervation in all other muscles tested in the lower and upper limbs. The distal compound muscle action potentials (CMAP) of the right median and ulnar nerves were attenuated. On proximal stimulation, these CMAPs were attenuated and dispersed. The motor conduction velocities were markedly slowed in the forearm segments of both median and ulnar nerves. The F-wave latencies from these nerves were prolonged. The right medial and lateral popliteal nerves could not be stimulated at the knee or ankle. The sural nerve sensory action potentials (SAP) were bilaterally absent. Median and ulnar nerve SAPs were in the low range of normal and the sensory conduction velocities were slow. The H-reflex was abolished on both sides. The left sixth rib was excised and biopsy of the rib lesion revealed palisading atypical plasma cells with altered nuclear:cytoplasmic ratio and mitotic figures suggestive of plasmacytoma [Figure 2]. A steady improvement in symptoms and signs was noted at six months follow up.

   »   Discussion Top

The present case illustrates a rare association between solitary plasmacytoma and peripheral neuropathy. The patient presented with symmetrical predominantly motor neuropathy with a mild sensory component. Pain and dysaesthesia were not present. Electromyography studies were suggestive of a symmetrical motor-sensory, predominantly demyelinating radiculoneuropathy with probable secondary axonal degeneration. This was corroborated by elevated proteins in the CSF. Investigations revealed clinically silent, underlying solitary plasmacytoma.

There are only few case reports in the literature of solitary plasmacytoma and peripheral neuropathy.[1],[2],[3],[4],[5],[6] These patients have distinctive and consistent clinical features when compared to those with neuropathy due to multiple myeloma [Table I]. As neuropathy precedes other clinical manifestations of this malignancy in most patients, diagnosis rests on detection of a monoclonal protein or solitary bone lesion. Therefore immuno-electrophoresis and detailed radiological survey should be done in all patients with predominantly motor neuropathy of undetermined aetiology. Solitary plasmacytoma tends to involve the axial skeleton i.e. ribs, scapula, vertebrae and pelvis and spares the skull and long bones. Radioisotope scans are less sensitive than plain x-rays for the detection of plasmacytoma.

As the lesion is usually localized and solitary, the monoclonal protein peak in these patients is usually small and may be obscured in serum protein electrophoresis, as was noted in our patient. More sensitive tests like immunoelectrophoresis or immunofixation should be done to detect `M' component. The urine immuno-electrophoresis is usually negative. It is interesting to note that majority of patients with solitary plasmacytoma had l light chain. This is in contrast to patients with multiple myeloma where k light chains predominate by 2:1 ratio.[7]

The majority of reported cases have shown some improvement in peripheral neuropathy with either surgical ablation or radiation therapy of the focal lesion. Out of 16 patients reviewed by Read and Warlow,4 ten patients who received local radiation therapy survived for ten years. Peripheral neuropathy had improved in all and progressed in none. Five had good recovery, three had moderate and two were lost to follow up. Addition of steroids or chemotherapy was of no added benefit. Six patients, who did not receive any treatment or received chemotherapy or steroids alone, died within seven to twenty months from the onset of the symptoms. Majority died due to pneumonia (unrelated to plasmacytoma). Kelly et al[5],[6] reviewed six patients of solitary plasmacytoma and peripheral neuropathy. One patient had a rib lesion. He died due to renal failure thirty two months after diagnosis. The postmortem study disclosed residual myeloma only in the rib. The other five had tumoricidal radiation therapy and all of them showed gradual improvement in neuropathy. Davis and Drachman[3] and Gupta and Prabhakar1 also reported similar experiences.

Improvement in neuropathy following treatment of solitary plasmacytoma suggests a probable pathogenic role for monoclonal protein. Detection of `M' protein on myelin sheath, schwann cells and endoneurial space in the nerve biopsy studies of four patients with POEMS syndrome[8] favors this hypothesis and justifies thorough investigations for and active treatment of the plasma cell proliferation. The class of `M' protein present in the nerve corresponded to that detected in the serum in all but one patient in this study.

There are very few reports in the literature depicting the natural history of solitary plasmacytoma. Meyer and Schulz[9] in their review of twelve cases with solitary plasmacytoma showed that most patients eventually develop multiple myeloma but they have protracted course. These patients may live for years without dissemination. This may be due to early detection and treatment coupled with a close follow up, to keep tumor load in control.

   »   Conclusion Top

Solitary plasmacytoma with peripheral neuropathy is rare. The peripheral neuropathy usually precedes the detection of malignancy. As these patients are asymptomatic for myeloma, the diagnosis may be missed. Hence, we recommend that radiological skeletal survey and serum immunoelectrophoresis be performed in all patients with `cryptogenic' polyneuropathy, particularly since response to surgical excision or radiation therapy of the focal lesion is gratifying.


  »   References Top

1.Rushton DI : Peripheral sensori-motor neuropathy associated with localized myeloma. BMJ 1965; 2 : 203-205.   Back to cited text no. 1    
2.Gupta SP, Prabhakar BR : Peripheral neuropathy and solitary plasmacytoma. BMJ 1965; 2 : 1004.  Back to cited text no. 2    
3.Davis LE, Drachman DB : Myeloma neuropathy, successful treatment of two patients and review of cases. Arch Neurol 1972; 27 : 507-511.  Back to cited text no. 3    
4.Read D, Warlow C : Solitary plasmacytoma with peripheral neuropathy. J Neurol Neurosurg Psychiatry 1978; 41 : 177-184.  Back to cited text no. 4    
5.Kelly JJ, Kyle RA, Miles JM et al : The spectrum of peripheral neuropathy in multiple myeloma. Neurology 1981; 31 : 24-31.  Back to cited text no. 5    
6.Kelly JJ, Kyle RA, Miles JM et al : Osteosclerotic myeloma and peripheral neuropathy. Neurology 1983; 33 : 202-210.   Back to cited text no. 6    
7.Kyle RA : Multiple myeloma, review of 869 cases. Mayo Clin Proc 1975; 50 : 29-40.  Back to cited text no. 7    
8.Adams D, Said G : Ultrastructural characterization of the M protein in nerve biopsy of patients with POEMS syndrome. J Neurol Neurosurg Psychiatry 1998; 64 : 809-812.  Back to cited text no. 8    
9.Meyer JE, Schulz MD : Solitary myeloma of bone, a review of twelve cases. Cancer 1974; 34 : 438-440.  Back to cited text no. 9    


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