Amyloidoma of bone, a plasma cell/plasmacytoid neoplasm. Report of three cases and review of the literature

Amyloid-Forming Corpora Amylacea and Spheroid-Type Amyloid Deposition: Comprehensive Analysis Using Immunohistochemistry, Proteomics, and a Literature Review

This study aimed to elucidate the similarities and differences between amyloid-forming corpora amylacea (CA) in the prostate and lung, examine the nature of CAs in cystic tumors of the atrioventricular node (CTAVN), and clarify the distinctions between amyloid-forming CA and spheroid-type amyloid deposition. We conducted proteomics analyses using liquid chromatography-tandem mass spectrometry with laser microdissection and immunohistochemistry to validate the characteristics of CAs in the lung and prostate. Our findings revealed that the CAs in these organs primarily consisted of common proteins (β2-microglobulin and lysozyme) and locally produced proteins. Moreover, we observed a discrepancy between the histopathological and proteomic analysis results in CTAVN-associated CAs. In addition, while the histopathological appearance of the amyloid-forming CAs and spheroid-type amyloid deposits were nearly identical, the latter deposition lacked β2-microglobulin and lysozyme and exhibited evident destruction of the surrounding tissue. A literature review further supported these findings. These results suggest that amyloid-forming CAs in the lung and prostate are formed through a shared mechanism, serving as waste containers (wasteosomes) and/or storage for excess proteins (functional amyloids). In contrast, we hypothesize that while amyloid-forming CA and spheroid-type amyloid deposits are formed, in part, through common mechanisms, the latter are pathological.

Cranial solitary osseous plasmacytoma and subjacent amyloid deposition in a dog

Solitary osseous plasmacytomas affecting the vertebrae, the zygomatic arch, and ribs occur in dogs. In this report, we describe clinical and imaging features of a solitary osseous plasmacytoma affecting the skull with deposition of amyloid forming a mass-like lesion. To the authors' knowledge, no similar cases have been reported before.

Severe hand pain as an extracardiac manifestation of transthyretin amyloidosis

Transthyretin amyloidosis is a multisystemic disease caused by the aggregation of amyloid fibrils, resulting in high morbidity and mortality in the presence of cardiac involvement. Patients often experience vague symptoms that make amyloidosis difficult to diagnose. Differential diagnosis for hand pain in a patient with systemic amyloidosis is broad. We present a patient with severe hand cramping and inability to perform activities of daily living. This preceded a new diagnosis of familial amyloid cardiomyopathy. The patient was a poor responder to systemic corticosteroids, anti-inflammatories and anticonvulsant therapy. Her unique presentation gives insight into a rare but debilitating disorder and the potential link between amyloidosis and other disease processes.

Tumours and Tumour - Like Lesions of Scapula

A retrospective study of 68 cases of tumours and tumour - like lesions related to the scapula, included in the registry of the Bone Tumour Reference Centre at the Institute of Pathology/University Clinics, Basle, has been carried out. Each case was evaluated for lesion entity, activity and location, age and sex of the patient, and, in 49 files with available radiographic documentation (mostly plain films), for radiologic appearance, with the aim to predict the histologic diagnosis or at least the correct dignity of the lesion. Statistically most frequent were cartilaginous tumours. More than 1/3 of all cases were osteochondromas, which demonstrated mostly a typical appearance. They were encountered predominantly in the first 3 decades in males and were located most often in the body of the scapula. 1/4 of all cases were chondrosarcomas, which were prevailing in the 4th-7th decades, but were occasionally found at a younger age too. Chondrosarcomas were located mainly at the lateral scapular margin over the inferior angle and in the acromion and coracoid process and their appearance ranged from typical to falsely benign. 1/3 of the cases represented a number of other benign and malignant histological entities.

Conditions Simulating Primary Bone Neoplasms

A number of nonneoplastic conditions can mimic tumors of bone. Some of the more common mimics of primary bone tumors include infectious, inflammatory, periosteal, and degenerative joint disease-associated lesions that produce tumorlike bone surface-based or intraosseous lesions. This article considers a spectrum of reactive and nonreactive processes including stress fracture, subchondral cysts, osteonecrosis, heterotopic ossification, osteomyelitis, sarcoidosis, and amyloidoma that can present in such a way that they are mistaken for a tumor arising primary in bone.

Cerebral amyloidoma is characterized by B-cell clonality and a stable clinical course

Amyloidomas are rare amyloid-containing lesions, which may also occur in the central nervous system. Etiology, pathogenesis and clinical course are poorly understood. To gain more insight into the biology of cerebral amyloidoma, they aimed to characterize its histopathological, molecular and clinical features in a retrospective series of seven patients. FFPE tissue specimens were examined using immunohistochemistry, chromogenic in situ hybridization (CISH) for light chains kappa and lambda as well as an IgH gene clonality analysis. Follow-up information was gathered by reviewing patient records and imaging results. Median age of the three males and four females was 50 years (range: 35-53 years). All cerebral amyloidomas were located supratentorially and were classified as lambda light chain amyloidosis (AL-λ; n = 6) and kappa light chain amyloidosis (AL-κ; n = 1) on immunohistochemistry and CISH. B-cell clonality was confirmed by IgH gene clonality assay in all cases examined. After a median follow-up of 21 months, all patients were alive and showed stable disease. No progression to systemic disease was observed. In conclusion, their data suggest that cerebral amyloidoma is a local disease characterized by B-cell clonality and associated with a stable clinical course.

Osteoprotegerin is a significant prognostic factor for overall survival in patients with primary systemic amyloidosis independent of the Mayo staging

Bone metabolism has not been systematically studied in primary (AL) amyloidosis. Thus we prospectively evaluated bone remodeling indices in 102 patients with newly diagnosed AL amyloidosis, 35 healthy controls, 35 newly diagnosed myeloma and 40 monoclonal gammopathy of undetermined significance patients. Bone resorption markers (C-telopeptide of type-1 collagen, N-telopeptide of type-1 collagen) and osteoclast regulators (soluble receptor activator of nuclear factor-κB ligand (sRANKL), osteoprotegerin (OPG)) were increased in AL patients compared with controls (P<0.01), but bone formation was unaffected. Myeloma patients had increased bone resorption and decreased bone formation compared with AL patients, while sRANKL/OPG ratio was markedly decreased in AL, due to elevated OPG in AL (P<0.001). OPG correlated with N-terminal pro-brain natriuretic peptide (P<0.001) and was higher in patients with cardiac involvement (P=0.028) and advanced Mayo stage (P=0.001). OPG levels above the upper value of healthy controls was associated with shorter survival (34 versus 91 months; P=0.026), while AL patients with OPG levels in the top quartile had very short survival (12 versus 58 months; P=0.024). In Mayo stage 1 disease, OPG identified patients with poor survival (12 versus >60 months; P=0.012). We conclude that increased OPG in AL is not only a compensation to osteoclast activation but may also reflect early cardiac damage and may identify patients at increased risk of death within those with earlier Mayo stage.

Calcified amyloid tumor of neck with exuberant giant cell reaction

Amyloidosis is a group of disorders characterized by an extracellular deposition of an abnormal amount of proteins in a variety of organs resulting from abnormal folding of protein. It typically presents as disseminated deposits. Tumor like localized presentation of amyloidosis in the absence of systemic amyloidosis is referred to as amyloidoma or amyloid tumor. Amyloidoma is the least common presentation of tissue amyloid deposition. Amyloidoma of soft tissue is again a very rare entity, especially in the neck region. Calcification and minimum giant cell reaction can occur in amyloidoma. However, extensive calcification and exuberant giant cell reaction in amyloidoma of soft tissue neck make it difficult to diagnose. In this report, we discuss such a rare case with its differential diagnoses.

18F-fluorodeoxyglucose positron emission tomography might be useful for diagnosis of hepatic amyloidosis

We report on a woman with hepatic involvement of primary systemic (immunoglobulin light chain, AL) amyloidosis. Her diagnosis was confirmed by liver biopsy. Clinical symptoms of hepatic amyloidosis are generally mild at its first stage, with most frequent findings being hepatomegaly and alkaline phosphatase elevation. Recent advances in the understanding of the pathophysiology of systemic amyloidosis have made several treatments available. However, its prognosis is occasionally poor. Because liver biopsy is not always safe, other modalities for the diagnosis are needed. Of interest was that fluorodeoxyglucose (FDG) uptake into the liver was observed, compared with that into the spleen, in this patient, indicating that FDG positron emission tomography and computed tomography might be useful for the diagnosis of hepatic amyloidosis with mild liver dysfunction.

Multiple myeloma-associated amyloidoma of the sacrum: case report and review of the literature

Study Design Case report. Objectives With only two previously reported cases, localized amyloidosis of the sacrum is extremely rare. Here we report a 64-year-old woman with a large osteolytic lesion accompanied by weakness and paresthesia of the right leg and difficulties in bladder control. Methods Fine needle biopsy and standard staging procedures revealed a primary solitary amyloidoma that was treated with intralesional resection, lumbopelvic stabilization, and consolidation radiotherapy. Results Clinical follow-up revealed the diagnosis of multiple myeloma 9 months after initial treatment. At 12 months, no local recurrence has occurred, the neurologic symptoms have resolved, and the systemic disease is in remission. Conclusions Intralesional resection with adjuvant radiotherapy of the amyloidoma achieved good local tumor control with limited morbidity.

Intraosseous calcifying epithelial odontogenic tumor in a case with multiple myeloma

Calcifying epithelial odontogenic tumor (CEOT), also known as Pindborg tumor, is a rare benign odontogenic tumor of locally aggressive behavior. It is more common in the posterior part of the mandible of adults, typically in the fourth to fifth decades. Its origin as well as its true malignant potential is not clearly known. It usually starts as a painless swelling and is often concurrent with an impacted tooth. A case of CEOT in a 55-year-old man with multiple myeloma is presented. Clinical, radiological, and pathologic findings are discussed.

Solitary amyloidoma related to THA

Amyloidoma of soft tissues is rare, and no previously published reports describe it in relation to hip prostheses. This article presents the case of a 78-year-old woman with a medical history of myelodysplasia and mild renal failure who underwent a right-sided metal-on-polyethylene total hip arthroplasty in 2003. She presented to the outpatient clinic with a 1-year history of right anterior thigh pain. On examination, a large proximal anteromedial lump was palpable and was nontender, nonpulsatile, and firm. She had a positive Trendelenburg test but good hip range of motion. Plain radiographs showed signs of osteolysis around the hip prosthesis. Serology showed mildly raised liver function and renal function but a normal erythrocyte sedimentation rate and white blood cell count. Magnetic resonance imaging revealed a large mixed-signal soft tissue mass directly opposing the anterior cortex of the right femur, related to the hip prosthesis, measuring 16×10×7 cm. Associated destruction of the underlying cortex existed. Histological staining of a biopsy of the mass confirmed that the mass contained AL-type amyloid seen in primary amyloidosis. Mean patient age at diagnosis for amyloid tumors of soft tissues is 66 years. By definition, they start as solitary lesions. The types are important: AA type is related to infection and AL type is a primary process. Patients with AL amyloidomas have a poorer prognosis because they have a higher chance of malignancies. Early diagnosis can prevent long-term serious consequences of this condition.

Isolated pulmonary amyloidomas: report of 3 cases with histologic and imaging findings

Amyloid tumors presenting as lung masses are rare. We report 3 patients seen over a 2-year period with multiple lung masses, 2 that were suspicious for metastasis, and one in a patient with chest pain. Pathologic evaluation demonstrated amyloid tumor in each case. Two demonstrated a prominent macrophage giant cell reaction; scattered polyclonal plasma cells were present in two of the cases. PET scanning of 2 of the patients revealed an SUV of 1.9 and 4.0, respectively. Short-term follow-up revealed that none of the 3 cases were associated with lymphoproliferative disorders. This small series and a literature review suggest that pulmonary amyloidomas are usually isolated lesions, and that PET may show increased uptake simulating a neoplasm.

Head and neck amyloidosis: clinicopathological features and immunohistochemical analysis of 14 cases

BACKGROUND

Amyloidosis is associated with or caused by amyloid deposition. These fibrillar proteins may be deposited extracellularly causing tissue damage or impairment.

OBJECTIVES

The aim of the study was to retrospectively review pathology archives in two oral diagnostic centers for cases fulfilling criteria of amyloidosis and to differentiate AA and AL types of amyloidosis.

METHODS

The clinicopathological features, alkaline Congo red staining, with and without pretreatment with potassium permanganate, and immunohistochemical (IHC) staining with anti-AA, anti-kappa (κ), and anti-lambda (λ) light chain antibodies were carried out and analyzed.

RESULTS

The search identified 14 cases. Ten patients were women and four were men, with a mean age of 58 years. Eleven patients had systemic involvement by amyloidosis (associated either with multiple myeloma or plasma cell dyscrasia/monoclonal gammopathies), while three presented the localized type, one of them associated with plasmacytoma. All cases showed positivity for κ or λ light chains (AL-amyloid) and presented resistance to the potassium permanganate pretreatment.

CONCLUSIONS

Our results show that the head and neck region is preferentially affected by systemic AL-amyloidosis, usually associated with plasma cell dyscrasia. Interestingly, two cases affected by inflammatory rheumatic diseases presented AL-amyloid deposition. Moreover, even after pretreatment with potassium permanganate, which was helpful in highlighting the presence of AL-amyloid, in agreement with the IHC findings, clinical classifications should be carefully made in systemic amyloidosis.

Fine-needle aspiration diagnosis of an intraosseous amyloidoma

Fine-needle aspiration (FNA) is frequently used as the initial diagnostic procedure for the investigation of bone and soft tissue masses. The majority of the lesions detected will represent metastatic carcinoma. Amyloid is a rare cause of a bone mass, with less than 15 published reports describing amyloid deposition within bone. The majority of reported cases involve the vertebral column. We report the finding of a massive amyloidoma of the iliac wing in a 46-year-old man. FNA smears and cell block preparations demonstrated fragments of waxy acellular material misinterpreted as necrotic debris. Subsequent open biopsy established the diagnosis of amyloid with congo red staining demonstrating apple green birefringence. Subsequent workup disclosed the patient to have anemia, hypogammaglobulinemia and trace monoclonal light chain gammopathy. Bone marrow examination revealed CD138a positive lambda restricted plasma cells consistent with plasma cell dyscrasia. Careful attention to the staining characteristics of amyloid in FNA derived material should allow the diagnosis of amyloidoma.

Multiple bony amyloidomas as an initial presentation of myeloma

Amyloidosis complicating multiple myeloma is an uncommon but well-recognized phenomenon. Multiple bone amyloidomas are rare as the initial presenting feature of myeloma. Solitary bone amyloidomas share common features with those of patients who have solitary plasmacytomas and progression to disseminated myeloma is common. We report a case of an elderly man who presented with extensive amyloid deposition in multiple plasmacytoma sites as well as evidence of amyloid in a fat pad aspirate but with none of the usual organ damage associated with systemic amyloidosis. This presentation is similar to a subset of patients said to have macrofocal myeloma. These patients are typically aged < 40 years, have no bone marrow involvement, and have a good prognosis. This report may represent the first description of macrofocal myeloma associated with amyloid deposition in an older individual.

Fixed digital contractures revealing light-chain amyloidosis

Among the many clinical manifestations of light-chain (AL) amyloidosis, musculoskeletal involvement is rarely reported. We describe the case of a 72-year-old woman who was referred to our rheumatology department for fixed flexion contractures of the fingers that developed concomitantly with a decline in general health. Macroglossia and recent-onset dyspnea were noted. Investigations, which included a tongue biopsy, established the diagnosis of kappa light-chain amyloidosis with soft-tissue, bone and cardiac deposits. Melphalan and dexamethasone therapy was successful in stabilizing the clinical and laboratory abnormalities within 6 months. This case is remarkable in that the musculoskeletal manifestations were at the forefront of the clinical picture and led to the diagnosis.

Extramedullary plasmocytoma associated with a massive deposit of amyloid in the duodenum

We report a rare case of extramedullary plasmocytoma associated with a massive deposit of amyloid in the duodenum. A 72-year-old Japanese man was admitted to our hospital presenting with a 3-mo history of epigastric pain, vomiting and weight loss. On computed tomography (CT) a wall thickening of the fourth part of the duodenum was observed. Multiple biopsies obtained from the lesion showed infiltration of plasma cells and lymphocytes, but they were not conclusive. The patient underwent resection of the lesion and, on histopathological examination, the lesion consisted of a dense and diffuse infiltrate of plasma cells and a few admixed lymphocytes with reactive follicles extending to the muscular propria. An extensive deposition of amyloid was also observed. Immunohistochemical stains revealed that a few plasmacytoid cells showed λ light chain staining, though most were κ light chain positive. These cells also were positive for CD138 and CD56 but negative for CD20 and CD79. The findings were consistent with extramedullary plasmocytoma associated with a massive deposit of amyloid in duodenum. A subsequent workup for multiple myeloma was completely negative. The patient showed no signs of local recurrence or dissemination of the disease after 12 mo follow-up. Because of the association of plasmocytoma and amyloidosis, the patient must be followed up because of the possible systemic involvement of the neoplasm and amyloidosis in future.

Amyloidoma: A Rare Cause of Soft Tissue Swelling in the Thigh

Soft tissue amyloidoma of the extremities is extremely rare and there are only 12 reported cases in the English literature to date. We present a case of soft tissue amyloidoma of the thigh in a 74-year-old lady.

Multiple amyloidomas in an HIV patient presented as inguinal and mediastinal masses: a case report diagnosed by fine-needle aspiration

Systemic amyloidosis can occur rarely as multiple masses with replacement of lymph nodes, causing lymphadenopathy and potentially mimicking neoplasms. We report a case of multiple amyloidomas in the inguinal lymph nodes and mediastinum in a 30-yr-old HIV positive woman with remote history of high grade dysplasia. Abundant amorphous material was obtained on fine-needle aspiration, making metastatic squamous cell carcinoma with abundant keratin a potential differential diagnosis. The prudent use of special stains such as Congo red, crystal violet, and immunohistochemical stains for keratin and kappa and beta light chains can be invaluable in helping to clarify the diagnosis. In patients with chronic inflammation, amyloidomas must be considered in the differential diagnosis of mass lesions so the appropriate work-up can be undertaken to minimize this potential pitfall.

The spectrum of localized amyloidosis: a case series of 20 patients and review of the literature

Localized deposition of amyloid may occur in individual organs, in the absence of systemic involvement. The reason for localized deposition is unknown, but it is hypothesized that deposits result from local synthesis of amyloid protein, rather than the deposition of light chains produced elsewhere. We identified 20 cases of localized amyloidosis at our institution between 1993 and 2003. There were 11 males and nine females in the group. The mean age at the time of diagnosis was 65.5 years. Organs involved included skin, soft tissues, oropharynx, larynx, lung, bladder, colon, conjunctiva, and lymph node. In six of nine patients typed, the amyloid light chain was lambda. In those patients where follow-up was available (mean 7.6 years), none developed systemic disease. Localized amyloidosis occurs in a variety of organ systems. Evolution into systemic amyloidosis was not seen in our series of patients, supporting the hypothesis of local production of amyloid protein in these cases.

Collapse in a 79-year-old: a rare case of amyloid tumour of the pelvis

A 79-year-old man presented to accident and emergency with collapse, unable to bear weight on his left leg. Computed tomography revealed a large isolated lesion (28 x 12 x 8 cm) extending from the pelvis into the abdomen, affecting the left lumbrosacral nerves. Further investigations showed that the mass contained amyloid protein. With no evidence of systemic amyloidosis or malignancy a diagnosis of amyloidoma/amyloid tumour was made. This is the largest amyloid tumour reported in the literature to date. There is limited but conflicting evidence regarding the pathophysiology, management and prognosis of amyloidoma. Clearly amyloidomas are rare, but patients can present acutely and may have a poor prognosis, especially when the tumour is of considerable size.

Primary Isolated Amyloidoma of the Lumbar Spine Causing Neurological Compromise: Case Report and Literature Review

OBJECTIVE AND IMPORTANCE:

We describe a patient with cauda equina compression secondary to amyloidoma to alert other clinicians to this rare cause of a compressive epidural lesion. It is the fourth published report of primary lumbar amyloidoma causing neurological compromise.

CLINICAL PRESENTATION:

A 53-year-old, previously fit salesman presented with several years history of back pain and recent weakness, especially in the left leg. He also had numbness and tingling radiating down the left leg. On examination, the left knee jerk was diminished, and both ankle jerks were absent. Power was reduced to 4/5 in ankle dorsiflexion bilaterally. A magnetic resonance imaging scan of the lumbar spine revealed an extradural mass, compressing the theca at L3–L4. This was enhancing in T1-weighted images and had low signal intensity in T2-weighted images. There was no evidence of systemic amyloidosis or development of multiple myeloma.

INTERVENTION:

L3–L4 laminectomy was performed, with removal of the epidural mass. The patient had complete resolution of sciatica and regained normal power in both lower limbs. There was no evidence of any recurrence at 1-year follow-up.

CONCLUSION:

Lumbar epidural amyloidoma is an extremely rare cause of cauda equina compression. Clinical presentation can be nonspecific, and radiologically, it can be indistinguishable from a tumor. Diagnosis is made at histological examination of a Congo red-stained section under polarized light. Complete resection of the localized epidural amyloid mass is associated with a good prognosis.

Recurrent Amyloidoma of Soft Tissue With Exuberant Giant Cell Reaction

Amyloidoma (localized tumorlike amyloidosis) in the soft tissues is rare. We present an instructive case of recurrent amyloidoma in the soft tissue of the ankle in a 45-year-old man with multiple surgical procedures and chronic osteomyelitis of the underlying bones. The lesion evaded diagnosis because of a florid giant cell reaction that led to various misdiagnoses, including giant cell tumor of tendon sheath, foreign body reaction secondary to surgery, and pseudogout. This case demonstrates the importance of considering the possibility of amyloidoma when a giant cell–rich lesion is encountered in the soft tissues.

Soft tissue amyloidoma with features of plasmacytoma: a case report and review

Soft tissue amyloidoma is rare, and soft tissue amyloidoma associated with plasmacytoma and without evidence of systemic amyloidosis is even more rare. We report a case of soft tissue amyloidoma associated with an apparently localized monoclonal proliferation of plasma cells (plasmacytoma).

Primary amyloidosis presenting as extensor tenosynovitis

Primary amyloidosis is a systemic disease. Amyloid arthropathy is an invalidating and uncommon form of presentation, but tenosynovitis is even rarer as the first sign of the disease. We report herein a case of unilateral amyloid deposit in the synovium of the extensor tendons of the hand, which was the first manifestation of a primary amyloidosis.

Primary amyloid tumor (amyloidoma) of the jejunum with spheroid type of amyloid

The present report documents an incidentally discovered, solitary amyloidoma of the jejunum in a 70 year old man with no predisposing disorder or other sites of deposition of amyloid, as was demonstrated at autopsy. Amyloid tumors of the intestine have been reported only rarely. In those reports the deposits were conventional in type, forming large masses of acellular, eosinophilic, homogeneous material. In the case described here the deposits were in the form of corpora amylacea-like structures, or spheroids. To the best of our knowledge, the corpora amylacea-like structures, or spheroid amyloid, have not been previously described in bowel amyloidoma. This rare form of amyloid deposition should be recognized so as to prevent misdiagnosis.

Intestinal multinodular A lambda-amyloid deposition associated with extramedullary plasmacytoma in three dogs: clinicopathological and immunohistochemical studies

Intestinal extramedullary plasmacytomas (EMPs) are rare tumours in dogs. Three cases of canine intestinal EMP with amyloid deposits are described in this report. These tumours, which were located in the rectal submucosa, had variable numbers of well-differentiated plasma cells and fewer multinucleated giant cells of plasmacytoid and histiocytic morphology, admixed with abundant amyloid. Two cases had metaplastic cartilage and bone within the amyloid deposits. Immunohistochemically, the plasma cells of all three tumours reacted for lambda-light chains of immunoglobulins but not for kappa-chains, indicating monoclonality. Plasma cells of two tumours were also positive to CD79a antiserum. Amyloid deposits were labelled with an A lambda (amyloid of immunoglobulin lambda-light chain origin) antiserum but not with antisera against its precursor protein, the immunoglobulin lambda-light chains, indicating possible conformational changes of amyloidogenic proteins during their transformation into amyloid.

Intestinal extramedullary plasmacytoma associated with amyloid deposition in three dogs: an ultrastructural and immunoelectron microscopic study

Samples from rectal plasmacytoma in three adult dogs that were diagnosed by light microscopy and immunohistochemistry were examined by electron microscopy. The most common cell type had typical plasmacytoid features. A second cell type was a plasmacytoid giant cell with single or multiple eccentric nuclei, irregular nuclear membrane, abundant and dilated rough endoplasmic reticulum, and numerous electron-dense granules. The third cell type was a histiocytic giant cell that intermingled with plasmacytoid cells. All three tumors had abundant amyloid, mainly in the interstitium but also within histiocytic cells and less commonly in plasma cells or plasmacytoid giant cells. Extracellular and intracellular amyloid fibrils and the contents of membrane-bound electron-dense bodies of plasma cells reacted with antibody to lambda-light chain of immunoglobulins by immunogold staining.

Amyloidomas of the nervous system: a monoclonal B-cell disorder with monotypic amyloid light chain lambda amyloid production

BACKGROUND

Amyloidomas or localized tumor-like amyloid deposits rarely affect the nervous system. To the authors' knowledge, no comprehensive studies on central and peripheral nervous system amyloidomas have been published. The amyloid subtype of amyloidomas of the nervous system only recently was characterized and almost invariably was found to be of amyloid light chain (AL) lambda type. The nature of the plasma cell population responsible for AL amyloid production has not been investigated further.

METHODS

The current analysis included the clinical findings, neuroimaging characteristics, and pathology of seven amyloidomas (four cerebral and three involving peripheral nerves). All were subjected to histochemical staining (Congo red, thioflavine S) and to immunohistochemical study using primary antibodies detecting serum amyloid component P, serum amyloid protein A (SAA), transthyretin, beta2 microglobulin (beta2m), and free immunoglobulin (Ig) light chain. For the detection of mRNA of light chain Ig, fluorescein-conjugated kappa and lambda mRNA oligonucleotide probes were used. For the assessment of B-cell clonality, polymerase chain reaction (PCR) was applied on extracted DNA from two cases using VH FRIII and JH primers. Two cases were assessed ultrastructurally.

RESULTS

All amyloidomas were organ restricted and unrelated to systemic amyloidosis. The clinical symptoms of the cerebral lesions were nonspecific, whereas neurologic deficits were noted in the distribution of the involved peripheral nerves. Cerebral deposits, either solitary or multiple, were associated spatially with the choroid plexus and secondarily extended into white matter. All peripheral nerve amyloidomas involved the gasserian ganglion of the trigeminal nerve. Imaging by computed tomography and magnetic resonance imaging scans revealed hyperdense and contrast-enhancing mass lesions unassociated with significant edema. Immunohistochemically, the amyloid was present in the interstitium and within the walls of the intralesional vessels, was invariably of AL lambda subtype, and was negative for free Ig kappa light chains, SAA, transthyretin, and beta2m. Plasma cells along the perivascular sheaths and occasionally squeezed between amyloid masses showed no cytologic atypia. In situ hybridization for Ig light chain mRNA reflected a massive preponderance of lambda-producing cells. PCR revealed monoclonal rearrangement of the heavy chain Ig gene.

CONCLUSIONS

The results of the current study provide strong support for the concept that amyloidomas of the nervous system are neoplasms of an AL lambda-producing B-cell clone capable of terminal differentiation. Nevertheless, all seven patients lacked clinical evidence of an aggressive or systemic lymphoplasmacytic neoplasm. Unlike plasmacytomas, the relatively indolent course of most nervous system amyloidomas is reminiscent of the similarly indolent biologic behavior of extranodal, low grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type.