Multiple myeloma is a disease of the plasma cells of the bone marrow, resulting in the proliferation and release of the monoclonal protein, which further causes end-organ damage. We report an unusual presentation of multiple myeloma, thereby insisting on the need for the treating physician to be aware of the various presentations that can be encountered in regular practice. It is often difficult to diagnose, and the diagnosis is usually made at a late stage of the disease. Even though uncurable, with recent advances, a proper regimen, newer chemotherapeutic agents, and stem cell transplantation, the disease can be brought into remission.

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AL amyloidosis (AL) is a systemic disorder due to extracellular tissue deposition of amyloid fibrils, composed of immunoglobulin light chains. Since the description of AL involving temporal arteries in 1986, this disorder has been known as one of the differential diagnoses of giant cell arteritis (GCA). We encountered a case of an elderly female presenting with headache and tender and enlarged temporal arteries, that was pathologically diagnosed with temporal artery involvement of AL due to Bence-Jones-type MM. To our knowledge, this was the first case of AL with temporal artery involvement in Japan, that presented with GCA-like features. Literature review of AL cases with temporal artery involvement showed close similarity between these disorders, but suggested that vasculature involvement (extremity claudication, kidney or heart), macroglossia, carpal tunnel syndrome and normal or low (<0.5 mg/dL) CRP levels may predict AL rather than GCA. Physicians should keep in mind that AL involving temporal arteries can be a pitfall in the diagnosis of GCA, as seen in our and previous cases.

A 77-year-old Japanese woman with a 21-year history of seropositive, erosive rheumatoid arthritis (RA) and a 10-year history of methotrexate (MTX) therapy was admitted with malaise and mild consciousness disturbance. Laboratory data showed hypercalcemia, acute kidney injury, normocytic anaemia, and thrombocytopenia. As we first assumed drug-induced toxicity by MTX and eldecalcitol, both were discontinued and leucovorin rescue therapy and calcitonin were administered. However, her condition continued to worsen. Serum protein electrophoresis showed only a small M-peak, immunoelectrophoresis of both the serum and urine demonstrated Bence-Jones kappa (κ) type monoclonal protein without immunoglobulin heavy chain, and bone marrow examination revealed proliferation of plasma cells. We diagnosed her with Bence-Jones κ type multiple myeloma (MM) and transferred her to the department of haematology of a higher order medical institution. Conclusively, the diagnosis of immunoglobulin (Ig) D-κ type MM, a rare variant of this disorder, was determined in accordance with serum immunofixation. Several previous studies have suggested that pre-existing RA is a risk factor for MM. Although IgD MM is characterised by its clinical severity and poor prognosis compared to other subtypes, it is often misdiagnosed or mistaken as light chain type MM, as in the present case, because of the low level of IgD M-protein, resulting in delayed diagnosis. Physicians must take MM into consideration as a differential diagnosis when inactive RA patients present with inexplicable elevated calcium, renal failure, anaemia, and bone lesion symptoms and should be aware of IgD MM to establish the correct diagnosis promptly.

BACKGROUND: This case highlights the importance of getting a thorough workup for acute kidney injury before assigning a diagnosis.
METHODS: A 68-year-old male was referred to our clinic after a recent outside hospitalization for septic knee arthritis and acute kidney injury requiring hemodialysis. He had chronic kidney disease presumed secondary to diabetes with baseline GFR 50 mL/min. He complained of fatigue and weight loss. Vital signs were within normal limits. Exam was notable for trace ankle edema, healed right knee scar, and right internal jugular hemodialysis catheter. Medications included amlodipine, aspirin, atorvastatin, furosemide, sevelamer, and cephalexin. Calculated creatinine clearance was 6 mL/min with urine output 2 L/day. Urinalysis showed 1+ protein, 2+ glucose, and fine granular casts. Clinical impression was ischemic acute tubular necrosis in recovery phase. However, when he did not improve and continued requiring dialysis, further workup showed elevated serum κ free light chains and urine Bence-Jones protein. Renal biopsy showed κ light chain crystalline tubulopathy, interstitial inflammation, and extensive fibrosis. Subsequent bone marrow biopsy showed 15% κ-restricted plasma cells. Multiple myeloma was diagnosed, and chemotherapy initiated. With decrease in κ light chain burden, kidney function improved, and patient was able to come off dialysis.
CONCLUSIONS: This case describes a rare presentation of κ light chain crystalline tubulopathy and illustrates the value of a comprehensive evaluation for acute kidney injury to enable prompt diagnosis and therapy.
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A 60-year-old man, who had been treated for chronic kidney disease and chronic hepatitis B infection, was referred to our hospital following presentation with thoracic bone pain and exacerbation of proteinuria and hematu- ria. On admission, laboratory test results showed evidence of hypophosphatemia, glucosuria and elevated levels of both urinary NAG and 62MG.The patient was diagnosed with Fanconi syndrome based on findings indicating the presence of pan-aminoaciduria, elevated urinary excretion of uric acid and an increased phosphorus reabsorption rate. Furthermore, bone scintigraphy showed increased multiple symmetric uptake of radiotracer in both sides of the ribs, leading to the diagnosis\"of hypoposphatemia-related osteomalacia with renal Fanconi syndrome. Urinary immunoelectrophoresis indicated the presence of K Bence Jones\' protein (BJP). A bone marrow biopsy examina- tion showed that the plasma-to-cell ratio was less than 10%. However, the patient had over lg/day of proteinuria and suppression of serum IgM (18mg/dL) and was, therefore, diagnosed with multiple myeloma based on SWOG criteria. Light microscopic examination showed evidence of glomerulosclerosis, intimal thickness of interlobular arteries and acidophilic granular deposits in the cytoplasm of the proximal epithelial tubular cells. Immunofluores- cence indicated positive anti-K staining in these regions. Electron microscopic examination of the proximal tubular epithelial cells revealed the presence of numerous diamond-shaped and oval crystals, thought to be the K light chain of BJP. In general, cast nephropathy, light chain deposition disease (LCDD) and AL amyloidosis are recog- nized renal injuries caused by myeloma. However, there have been few clinical reports of Fanconi syndrome with multiple myeloma, such as the case study we have described here. In addition, histological examination of a biopsy sample provided further evidence of K BJP in the proximal epithelial tubular cells.

Multiple myeloma (MM) is characterized, in about 80% of cases, by the production of monoclonal intact immunoglobulin and more than 95% of them have elevated concentrations of involved (i.e. of the same class of intact immunoglobulin) free light chain (FLC). The introduction of novel therapeutic strategies has changed the natural history of the disease, leading to new manifestations of relapse. Light chain escape (LCE) is a pattern of relapse in which the FLC increase is not accompanied by a concomitant raise of the original monoclonal component (MC). Here we present a case of a 55-year-old man with an IgG kappa MM stage III diagnosed in September 2007. At presentation an IgG kappa MC and urine Bence Jones protein (BJP) kappa were present. Bone marrow biopsy (BMB) showed the presence of 80% monotypic kappa plasma cells (PCs). The patient received bortezomib, thalidomide, dexamethasone before undergoing a double autologous stem cell transplantation (ASCT) in October 2008 and April 2009. In May 2011 he relapsed showing the same pattern of presentation and treatment with lenalidomide and dexamethasone was started. ln May 2013 serum and urine immunofixation and FLC became negative. In September 2014, an increase of kappa FLC was observed, while serum and urine immunofixations remained negative until January 2015, when urine immunofixation became positive. Eventually, in February 2015, serum immunofixation revealed the presence of a free kappa MC. After a new BMB showing 80% of monotypic kappa PCs, a LCE relapse was diagnosed and the patient started the treatment with bendamustine, bortezomib and dexamethasone. In the present case, the increase of kappa FLC has indicated relapse 4 and 5 months earlier than urine and serum IFE, respectively. Our observation confirms that it is advisable to routinely perform FLC or BJP during follow up of MM patients undergoing ASCT and/or treatment with biological drugs to ensure that LCE is not missed.

A 39-year-old female patient was admitted to explore chronic renal failure. Clinical history included silicone breast implants. Clinical examination was normal. Urinalysis revealed tubular proteinuria with Bence-Jones κ protein. Monoclonal immunoglobulin G κ and free monoclonal κ-light chains (LCs) were revealed by serum protein immunoelectrophoresis. Bone marrow aspiration with karyotype analysis and skeletal radiologic survey were normal. Kidney biopsy revealed a peculiar pattern of proximal tubular cells with hypertrophy and clarification initially diagnosed as an osmotic nephrosis. Immunofluorescence study, including immunoglobulin LCs conjugates was normal. Immunoelectron microscopy finally revealed a crystalline LC proximal tubulopathy κ. Our case presents some peculiarities: the absence of hematologic malignancy sign and the young patient\'s age. The silicone breast implants have been reported to be involved in the generation of monoclonal gammopathy.

This study reports a 59-year-old man who suffered from multiple skeletal muscle amyloidomas and showed a rapidly fatal course. He noticed left inguinal pain and gait disturbance due to muscle weakness of the left leg. Protein in urine (3.3 g/d) and Bence-Jones protein of the κ type (2.3 g/d) were detected. Bone marrow aspiration showed 11.6% monoclonal plasma cells in nucleated cells. A core needle-biopsied and resected left inguinal tumor showed the deposition of eosinophilic amorphous materials positive for Congo red stain and the κ-light chain. He was diagnosed with plasma cell myeloma with AL (amyloid light chain) amyloidosis. Multiple soft-part tumors developed, grew rapidly, and he died 3 months after admission. At autopsy, 3 large amyloidomas were observed in the skeletal muscles, and prominent amyloid deposits were also seen in the diaphragm, intercostal muscle, iliopsoas muscle, and cervical skeletal muscles examined. Massive amyloid materials deposited diffusely in the propria muscularis of the gastrointestinal tract: the tongue to the rectum.

A 69-year-old man was referred to our hospital for severe anemia. The atypical lymphocyte count, including granular lymphocytes, was 2,750/μL. Lymphocyte surface marker analysis showed CD3+, CD5+, CD16+, and CD56+ cells. Mixed T cell- and natural killer cell-type granular lymphocyte proliferative disorder (GLPD) was diagnosed. Because his serum creatinine levels deteriorated rapidly over the next 3 months, from 0.96 to 3.27 mg/dL, he was admitted to our hospital. The serum levels of immunoglobulins (Ig) other than IgD had decreased, and monoclonal protein was detected in the gamma-globulin region. Immunoelectrophoresis revealed IgD and lambda (λ) proteins in the serum and λ-type Bence-Jones protein in the urine. Renal biopsy examination revealed widespread tubular atrophy and interstitial fibrosis, and cast formation with λ protein deposits in tubular lumens, indicating cast nephropathy. These results indicated that the rapid renal damage was caused by IgD λ-type multiple myeloma accompanied by GLPD. The clinical course of GLPD is not usually aggressive and the findings of physical examinations are not significant. GLPD is usually associated with cytopenia (neutropenia or anemia), viral infections, collagen diseases, neoplasms such as malignant lymphoma, or chronic infections. To date, there are only 2 case reports of GLPD accompanied by multiple myeloma but without renal function or renal histological findings. When the clinical course of GLPD is aggressive and is accompanied with rapid renal damage, multiple myeloma should be considered as a complication.