Crystal-storing histiocytosis involving the kidney in a low-grade B-cell lymphoproliferative disorder

Monoclonal immunoglobulin crystalline nephropathies

Monoclonal Ig crystalline nephropathies are rare lesions resulting from precipitation of monoclonal Igs in the kidney as crystalline inclusions. They can be categorized into lesions with predominant intracellular crystals (light chain [LC] proximal tubulopathy, LC crystal-storing histiocytosis, and LC crystalline podocytopathy) and lesions with predominant extracellular crystals (crystalglobulin-induced nephropathy and crystalline variant of LC cast nephropathy). The majority of these lesions are associated with low tumor burden lymphoproliferative disorders, with the exception of crystalline variant of LC cast nephropathy. Extrarenal involvement (e.g., skin and cornea) is frequent. Kidney biopsy is the cornerstone for diagnosis, which often requires electron microscopy and antigen retrieval. A thorough hematologic workup and evaluation of extrarenal involvement is mandatory for management. Treatment of these lesions is with clone-directed therapy, with the goal of achieving hematologic very good partial response or complete response, which preserves or improves kidney function. In vitro and in vivo studies, animal models, and novel sequencing techniques have been invaluable tools to understand the pathogenesis of LC proximal tubulopathy and can be used to increase our limited knowledge of the pathogenesis of the other monoclonal Ig crystalline nephropathies. This review provides an update on the pathology, renal and hematologic characteristics, extrarenal manifestations, prognosis, treatment, and pathogenesis of monoclonal Ig crystalline nephropathies.

Combined crystal-storing histiocytosis, light chain proximal tubulopathy, and light chain crystalline podocytopathy in a patient with multiple myeloma: a case report and literature review

BACKGROUND

Crystal-storing histiocytosis (CSH), light chain proximal tubulopathy (LCPT), and light chain crystalline podocytopathy (LCCP) are rare complications of multiple myeloma (MM) or monoclonal gammopathy of renal significance, and their diagnoses are challenging.

CASE PRESENTATION

In this case, a 69-year-old Chinese woman presented with suspicious Fanconi syndrome with renal insufficiency. Immunofixation electrophoresis of both serum and urine revealed elevated immunoglobulin G kappa (IgGkappa) and kappa light chain. Bone marrow aspirate revealed 15% plasma cells with considerable cytoplasmic granular inclusions and needle-shaped crystals. Renal biopsy confirmed the final pathologic diagnosis of kappa-restricted CSH, combined LCPT and LCCP by immunoelectron microscopy. A number of special casts were present which could easily be misdiagnosed as light chain cast nephropathy. Immunofluorescence on frozen tissue presented false negative for kappa light chain, as ultimately proven by paraffin-embedded tissue after pronase digestion. MM and CSH were diagnosed, and two cycles of chemotherapy were given. The patient subsequently refused further chemotherapy, and her renal function remained relatively stable during a 2.5-year follow-up period.

CONCLUSIONS

In conclusion, we report a rare case of generalized kappa-restricted CSH involving bone marrow and kidney, combined with LCPT and LCCP, provide a comprehensive summary of renal CSH, and propose a new nomenclature of monoclonal immunoglobulin-induced crystalline nephrology. The presentation of monoclonal immunoglobulin and Fanconi syndrome should suggest the presence of monoclonal immunoglobulin-induced crystalline nephrology. Use of paraffin-embedded tissue after pronase digestion and immunoelectron microscopy is beneficial to improve the sensitivity of diagnosis.

Crystal-Storing Histiocytosis: The Iceberg of More Serious Conditions

Crystal-storing histiocytosis is a rare condition that is histologically characterized by intracellular cytoplasmic crystalline inclusions. It usually presents monoclonal immunoglobulins that deposit within histiocytes, which accumulate and affect different organs of the human body and are commonly associated with lymphoproliferative conditions, especially those with plasmacytic differentiation. The prognosis of this condition is variable and related to the underlying clinical disease. In this review article, we aim to describe and discuss the clinical and pathological characteristics of crystal-storing histiocytosis based on the available literature and to provide a thorough differential diagnosis.

Combined renal proximal tubulopathy and crystal storing histiocytosis in a patient with κ light chain multiple myeloma

Multiple myeloma accounts for 10-15% of all hematologic malignancies, and 20% of deaths related to cancers of the blood and bone marrow. Diagnosis is defined by the presence of a serum monoclonal spike (M-spike) of more than 3 g/dL or more than 10% clonal plasma cells in the bone marrow and at least one myeloma-defining event, such as hypercalcemia, anemia, bone lesions, or renal impairment. The kidney is a major target organ, and renal impairment is frequently the first manifestation of the disease. Renal damage occurs in up to 40% of patients and 10-20% will require dialysis. Monoclonal immunoglobulin light chains are the major causes of renal complications in multiple myeloma. Glomerular disease, with the deposition of monoclonal immunoglobulins or their components, includes monoclonal immunoglobulin deposition disease, AL or AH amyloidosis, type I cryoglobulinemia, proliferative glomerulonephritis with monoclonal IgG deposits, immunotactoid glomerulopathy, and fibrillary glomerulonephritis. In addition, tubulointerstitial diseases with the deposition of monoclonal immunoglobulins or their components, are constituted by light chain cast nephropathy, light chain proximal tubulopathy, and crystal-storing histiocytosis.

We report the case of a 66-year-old woman who presented with albumin-predominant moderate proteinuria and renal failure. Serum and urine immunofixation electrophoresis showed monoclonal κ light chain in both. Renal biopsy confirmed κ-restricted crystal-storing renal disease involving proximal tubular epithelial cells and crystal storing histiocytosis. Multiple myeloma with crystal storing histiocytosis was discovered in bone marrow biopsy. Thus, we present an unusual case of a myeloma patient presenting light chain proximal tubulopathy and crystal-storing histiocytosis both in the kidney and in the bone marrow.

Immunoglobulin-Storing Histiocytosis: A Case Based Systemic Review

Crystal-storing histiocytosis (CSH) is a rare event in disorders associated with monoclonal gammopathy and is mostly associated with the accumulation of immunoglobulins (Igs) in the cytoplasm of histiocytes. In this article, we present a case of a 75-year-old female with IgG kappa monoclonal gammopathy of undetermined significance (MGUS) and signs of a non-crystallized version of immunoglobulin-storing histiocytosis (IgSH) in a vertebra corpus. Furthermore, we performed a literature review based on all cases of storing histiocytosis identified by literature search between 1987 and 2020 and identified 140 cases in total. The median age at diagnosis was 60 years (range 18–91), with an equal sex distribution (51% men). The majority of the patients had an underlying neoplastic B-cell disorder, most often multiple myeloma (MM), MGUS, or lymphoplasmacytic lymphoma (LPL). The main affected organ systems or tissue sites were bone (n = 52), followed by head and neck (n = 31), kidney (n = 23), lung (n = 20), and gastrointestinal (GI)-tract (n = 18). IgG was the main immunoglobulin class involved, and most cases were associated with kappa light chain expression. We conclude that IgSH is a rare disease entity but should be considered with unusual findings in several organ systems associated with monoclonal gammopathy, especially with kappa light chain expression.

Crystalglobulin-associated nephropathy presenting as MGRS in a case of monoclonal B-cell lymphocytosis: a case report

BACKGROUND

Crystalglobulin-associated nephropathy (CAN), a rare subtype of monoclonal gammopathy, usually associated with multiple myeloma and occasionally monoclonal gammopathy of uncertain significance (MGUS), is characterized by occluding monoclonal pseudothrombi within renal glomerular capillaries and/or interstitial arterioles. Ultrastructurally, these pseudothrombi are unique for having a crystalline substructure. We describe a case of an adult patient with monoclonal B-cell lymphocytosis (MBL) and acute renal failure whose kidney biopsy revealed a rare diagnosis of CAN.

CASE PRESENTATION

A 63-year old male presented with a 2-month history of edema, arthralgia and malaise. He had acute kidney injury with hematoproteinuria on urine analysis. Serum and urine protein electrophoresis were both negative. A renal biopsy however revealed features of CAN. Organomegaly, bone pain and lymphadenopathy were absent. A repeat serum electrophoresis was positive for IgA kappa and a free light chain assay showed elevated free kappa light chains. Flow cytometry done subsequently revealed a diagnosis of MBL, chronic lymphocytic leukemia (CLL) type.

CONCLUSION

CAN in association with MBL/CLL has not been previously described in literature, and our case highlights yet another instance of monoclonal gammopathy of renal significance (MGRS) where a small B-cell clone resulted in extensive renal pathology without systemic manifestations.

Renal crystal-storing histiocytosis involving glomeruli - A comprehensive clinicopathologic analysis

Crystal-storing histiocytosis (CSH) is a rare manifestation of monoclonal gammopathy in which histiocytes containing monoclonal proteins in their cytoplasm are found in various organs of the body including the kidney. Within the kidney, these monoclonal crystal-laden histiocytes have been described to occur in the interstitium (most commonly) or in the glomerular mesangium. CSH within glomerular capillary loops has rarely been reported. We describe three cases of CSH primarily affecting the glomerular capillaries and review the literature of CSH in general. Twenty cases of CSH involving the kidney are present in the literature; three describe CSH in glomeruli, only one of which showed histiocytes predominantly in glomerular capillary loops, while 15 had predominantly or solely interstitial CSH. Most cases involve IgG kappa crystals with only one case involving lambda light chain. Patients with CSH predominantly involving the glomerular capillaries showed a trend toward lower serum creatinine and proteinuria at presentation, and several patients with CSH lacked a definitive diagnosis of a monoclonal gammopathy at the time of diagnosis, emphasizing the role that kidney biopsy and particularly electron microscopy play in diagnosis of this entity.

Massive generalized crystal-storing histiocytosis associated with extracellular crystalline nephropathy: clinical, immunohistochemical, and ultrastructural studies of a unique disorder and review of the literature

Crystal-storing histiocytosis (CSH) is a rare disorder characterized by the accumulation of nonneoplastic histiocytes containing intracytoplasmic crystallized immunoglobulins. In most cases, there is an associated underlying lymphoplasmacytic neoplasm expressing Ig kappa light chain. About 131 cases of CSH have been identified. There is a localized and a generalized form of CSH and it can involve several sites including bone marrow, lungs, lymph nodes, liver, spleen, gastrointestinal tract, and kidney. Generalized CSH is less frequent and involves multiple organs and tends to have a worst prognosis than localized CSH. Around 20 cases of renal involvement in CSH have been reported so far. Paraprotein-induced crystalline nephropathy can be divided into two categories based on whether the crystals in the kidney are intracellular (including light chain proximal tubulopathy with crystals and CSH) or extracellular (including the crystalline variant of myeloma cast nephropathy and crystalglobulin-induced nephropathy). The former tends to present with slowly worsening kidney dysfunction and generally has a good prognosis, whereas the latter usually presents with rapidly progressive renal failure and is associated with poor renal outcome. We present a case of generalized CSH associated with extracellular crystalline nephropathy with a fulminant and fatal clinical course. Kappa light-chain crystals were found exclusively extracellularly within the tubular lumen, not within the tubular epithelial cells nor the histiocytes, and the massive presence of those precipitates led to the acute renal failure. Consequently, we review the renal involvement in CSH in the literature and discuss the unique mechanism of renal injury in this case.

Monoclonal light chain crystalline podocytopathy and tubulopathy associated with monoclonal gammopathy of renal significance: a case report and literature review

Background

Monoclonal gammopathy of renal significance (MGRS) is a recently defined group of renal diseases caused by monoclonal immunoglobulin secreted by nonmalignant proliferative B cell or plasma cell. Monoclonal immunoglobulin can form different types of structures deposited in renal tissue, including fibrils, granules, microtubules, crystals and casts, and has mostly been reported in multiple myeloma patients. Here we report a rare case with κ light chain crystals in both podocytes and tubular epithelial cells associated with MGRS, which adds more information to the spectrum of MGRS-related renal diseases.

Case presentation

A 53-year old woman presented with albumin–predominant moderate proteinuria and renal failure. She had monoclonal IgGκ in the serum and monoclonal IgGκ plus free κ in the urine. Multiple myeloma and lymphoproliferative disorders were excluded. Renal biopsy confirmed κ-restricted crystal-storing renal disease involving the podocytes and proximal tubular epithelial cells. The patient was treated with bortezomib followed by lenalidomide-based chemotherapy, and renal function was stable after 1 year of follow-up.

Conclusions

This is a rare case of combined crystalline podocytopathy and tubulopathy associated with MGRS, in which diagnosis was dependent on electron and immuno-electron microscopy.

The Complexity and Heterogeneity of Monoclonal Immunoglobulin-Associated Renal Diseases

Monoclonal gammopathies are characterized by the overproduction of monoclonal Ig (MIg) detectable in the serum or urine resulting from a clonal proliferation of plasma cells or B lymphocytes. The underlying hematologic conditions range from malignant neoplasms of plasma cells or B lymphocytes, including multiple myeloma and B-cell lymphoproliferative disorders, to nonmalignant small clonal proliferations. The term MGUS implies presence of an MIg in the setting of a "benign" hematologic condition without renal or other end organ damage. The term MGRS was recently introduced to indicate monoclonal gammopathy with MIg-associated renal disease in the absence of hematologic malignancy. Most MIg-associated renal diseases result from the direct deposition of nephrotoxic MIg or its light- or heavy-chain fragments in various renal tissue compartments. Immunofluorescence microscopy is essential to identify the offending MIg and define its tissue distribution. Mass spectrometry is helpful in difficult cases. Conditions caused by direct tissue deposition of MIg include common disorders, such as cast nephropathy, amyloidosis, and MIg deposition diseases, as well as uncommon disorders, such as immunotactoid glomerulopathy, proliferative GN with MIg deposits, light-chain proximal tubulopathy, and the rare entities of crystal-storing histiocytosis and crystalglobulinemia. Indirect mechanisms of MIg-induced renal disease can cause C3 glomerulopathy or thrombotic microangiopathy without tissue MIg deposits. Treatment of MIg-associated renal disease is aimed at eliminating the clonal plasma cell or B-cell population as appropriate. Both the renal and the underlying hematologic disorders influence the management and prognosis of MIg-associated renal diseases.

Combined proximal tubulopathy, crystal-storing histiocytosis, and cast nephropathy in a patient with light chain multiple myeloma

Background

The diagnosis of myeloma, a plasma dyscrasia, often results from the workup of unexplained renal disease. Persistent renal failure in myeloma is commonly caused by tubular nephropathy due to circulating immunoglobulins and free light chains. Myeloma cast nephropathy is characterized by crystalline precipitates of monoclonal light chains within distal tubules. Immunoglobulin crystallization rarely occurs intracellularly, within proximal tubular cells (light chain proximal tubulopathy) and interstitial histiocytes (crystal-storing histiocytosis). We present a case report of a rare simultaneous occurrence of light chain proximal tubulopathy, crystal-storing histiocytosis, and myeloma cast nephropathy in a patient with κ light chain multiple myeloma.

Case presentation

A 48-years-old man presented with uremia and anemia. Laboratory examination revealed low levels of serum IgG, IgA, and IgM. Serum and urine immunofixation electrophoresis showed a free κ monoclonal band. Bone marrow aspiration and biopsy revealed hypercellularity with marked plasmacytosis. Light microscopy revealed eosinophilic cuboid- and rhomboid-shaped crystals in the cytoplasm of proximal tubular epithelial cells, diffuse large mononuclear and multinuclear cells in the interstitium, and obstructed distal tubules with cast and giant cell reaction. Immunohistochemical examination indicated intense staining for κ light chains within casts, histiocytes, and tubular epithelial cells. Electron microscopy revealed electro-dense cuboid-, rhomboid-, or needle-shaped crystalline inclusions in proximal tubular epithelial cells and interstitial histiocytes. According to these results, we confirmed that this patient with myeloma exhibited simultaneous light chain proximal tubulopathy, crystal-storing histiocytosis, and myeloma cast nephropathy, which were attributed to monoclonal κ light chains. In addition to dialysis, the patient received induction chemotherapy with a combination of bortezomib, cyclophosphamide, and dexamethasone, followed by maintenance therapy with thalidomide. However, the patient did not regain renal function even when less than 5% plasma cells were detected in the bone marrow.

Conclusion

To the best of our knowledge, this is the first report of simultaneous light chain proximal tubulopathy, crystal-storing histiocytosis, and myeloma cast nephropathy in κ light chain multiple myeloma.

Spectrum of manifestations of monoclonal gammopathy-associated renal lesions

PURPOSE OF REVIEW

Monoclonal gammopathies result from an overt malignant process, such as multiple myeloma, or a premalignant process, such as monoclonal gammopathy of undetermined significance. The kidney is often affected in the setting of a monoclonal gammopathy. The term 'monoclonal gammopathy of renal significance (MGRS)' was recently introduced to draw attention to renal diseases related to the monoclonal gammopathy. In this review, we define the pathology of these monoclonal gammopathy-associated kidney diseases.

RECENT FINDINGS

Renal disease can be caused by deposition of the monoclonal immunoglobulin (direct mechanism) or by activation of the alternative pathway of complement by the monoclonal immunoglobulin (indirect mechanism). The deposition of monoclonal immunoglobulin can affect the glomeruli, tubules, and the interstitium and vessels. The glomerular diseases include proliferative glomerulonephritis with monoclonal immunoglobulin deposits, immunotactoid glomerulopathy, and, less commonly, fibrillary glomerulonephritis. Tubular lesions associated with monoclonal immunoglobulin include cast nephropathy and light-chain proximal tubulopathy. Lesions involving the glomeruli, tubules, interstitium or vessels include amyloidosis and monoclonal immunoglobulin deposition diseases. Rarely, monoclonal immunoglobulin may also cause C3 glomerulopathy or atypical hemolytic uremic syndrome by interfering with the regulation of the alternative pathway of complement.

SUMMARY

Monoclonal gammopathy are associated with a variety of kidney diseases. The monoclonal gammopathy-associated renal diseases are distinct in their pathogenesis, kidney biopsy findings, clinical presentation, progression, prognosis, and treatment. The term monoclonal gammopathy of renal significance helps highlight patients who have renal disease secondary to monoclonal immunoglobulin secreted by a premalignant or malignant clone, but is not a disease or diagnosis in itself.

Unique Renal Manifestation of Type I Cryoglobulinemia, With Massive Crystalloid Deposits in Glomerular Histiocytes, Podocytes, and Endothelial Cells

OBJECTIVES

We describe a 62-year-old woman with a 15-year history of a plasma cell dyscrasia (monoclonal IgGκ), manifested by type I cryoglobulinemia and dermal vasculitis.

METHODS

In addition to the clinical examinations, light microscopy with immunohistochemistry, sequential multicolor immunohistochemistry, and electron microscopy were used to characterize the crystalline deposits.

RESULTS

At initial presentation and for a later flare, she was treated with cyclophosphamide and prednisolone with good clinical response. She had renal function decline, microscopic hematuria, and proteinuria. A renal biopsy specimen revealed the presence of glomerular macrophages and duplication of the capillary walls with cellular interposition. Glomerular cells contained abundant needle-shaped eosinophilic crystalline inclusions positive for κ light chain. Electron microscopy confirmed the presence of intracytoplasmatic crystalline structures in endothelial cells, podocytes, and macrophages but not in the tubular epithelium. Rituximab treatment was started. At follow-up (now up to 6 months), renal function remained stable.

CONCLUSIONS

This patient displays a unique renal manifestation of type I cryoglobulinemia related to a plasma cell dyscrasia.

Histiocytic and Nonhistiocytic Glomerular Lesions: Foam Cells and Their Mimickers

Numerous histiocytes are sometimes noted in glomeruli, giving rise to a foamy-appearing glomerulus. Foamy-appearing glomeruli may also be noted in conditions that do not contain numerous histiocytes. These disease entities are rare, have different underlying causes and pathophysiology, and can cause a diagnostic dilemma. We have observed this histiocytic/foamy glomerular change on the kidney biopsy specimen in 5 different disease entities: crystal-storing histiocytosis, histiocytic glomerulopathy associated with macrophage-activating syndrome, thrombotic microangiopathy, lecithin-cholesterol acyltransferase deficiency, and lipoprotein glomerulopathy. We describe and compare the kidney biopsy findings of these histiocytic and foamy-appearing entities. It is important to recognize the kidney biopsy findings of these rare conditions to correctly evaluate and identify the cause and manage these patients.

Pseudo-Peritoneal Carcinomatosis Presentation of a Crystal-Storing Histiocytosis With an Unmutated Monoclonal κ Light Chain

Crystal-storing histiocytosis (CSH) is a rare complication of monoclonal gammopathies caused by accumulation of crystalline material inside macrophages, and it may result in a variety of clinical manifestations depending on the involved organs. Although immunoglobulin κ light chains (LCs) seem to be the most frequent pathogenic component, very few molecular data are currently available.A 69-year-old man presented with a very poor performance status. Remarkable features were mesenteric lymph node enlargement and proteinuria, including a monoclonal κ LC. Light and electron microscopy studies revealed the presence of crystals within macrophages in the lymph nodes, bone marrow, and kidney, leading to the diagnosis of CSH. The pathogenic κ LC variable domain sequence was identical to the germline Vk3-2001/Jk201 gene segments, without any somatic mutation, suggesting an extra-follicular B cell proliferation.The patient was successfully treated with 4 cycles of bortezomib and dexamethasone. After a 12-month follow-up, he remains in hematological and renal remission.CSH may present as pseudo-peritoneal carcinomatosis and relate to a monoclonal κ LC encoded by an unmutated gene. Bortezomib-based therapy proved efficacious in this case.

A case of endocapillary proliferative glomerulonephritis with macrophages phagocytosing monoclonal immunoglobulin lambda light chain

Multiple myeloma (MM) is a plasma-cell neoplasm that can cause renal disorders. Renal lesions in MM can present with a very rare pathological manifestation involving a specific monoclonal immunoglobulin (Ig). We report the case of a 33-year-old woman who had edema, fatigue, elevated serum creatinine levels, hypoalbuminemia, and hypercholesterolemia. She had persistent hematuria and proteinuria lasting 3 years. Serum protein electrophoresis showed an M-spike, and serum immunofixation demonstrated the presence of monoclonal IgG λ. She had proteinuria in the nephrotic range, and a monoclonal λ fragment was present on urine immunofixation. Renal biopsy showed proliferative glomerulonephritis with λ light chain and C3c deposition and inflammatory cell infiltration with CD68. Macrophage lysosomes contained λ light chains, suggesting their partial phagocytosis. She was diagnosed with symptomatic MM and was treated with bortezomib and dexamethasone and an autologous peripheral stem cell transplant conditioned with intravenous melphalan. She achieved a partial response with decreased serum monoclonal protein and improved renal function. This case may be categorized as a monoclonal gammopathy-associated proliferative glomerulonephritis. The biopsy finding of partially phagocytosed Ig λ light chains by macrophages is very rare; this pathological condition is similar to crystal-storing histiocytosis.

Crystal-Storing Histiocytosis Complicating Primary Pulmonary Marginal Zone Lymphoma of Mucosa-Associated Lymphoid Tissue

Crystal-storing histiocytosis is an uncommon form of nonneoplastic histiocytic proliferation that in most patients complicates an underlying lymphoproliferative or plasma cell disorder. Lung is a common site of involvement in patients with localized disease. We present an illustrative example from a 54-year-old woman with an asymptomatic solitary lung nodule. The tumor was characterized by sheets of histiocytes with abundant cytoplasm expanded by distinctive eosinophilic inclusions. Focal necrosis was present. Aggregates of monocytoid lymphocytes and clusters of peribronchiolar plasma cells were overshadowed by the histiocytic infiltrate. Immunohistochemical stains showed CD68 staining in nonneoplastic histiocytes and CD20 staining in monocytoid lymphocytes. In situ hybridization studies showed κ light-chain restriction in plasma cells. These results, combined with the histologic findings, supported the diagnosis of crystal-storing histiocytosis complicating marginal zone lymphoma of mucosa-associated lymphoid tissue. We review the literature pertaining to pulmonary crystal-storing histiocytosis, highlighting the differential diagnosis for this rare phenomenon.

Crystal-storing histiocytosis: report of a case, review of the literature (80 cases) and a proposed classification

We report a case of crystal storing histiocytosis (CSH) of the upper lip and cheek in a 51-year-old woman and review the clinicopathologic features of 80 cases in the literature. These occurred in 41 men and 39 women with a respective mean age of 59 and 61 years (range 17-81 years). Forty-six patients (58%) had localized CSH, and, of these, 16 (35%) occurred in the head and neck, with the most common site being the eye/orbit. The remaining 34 patients (42%) had generalized CSH primarily involving bone marrow, liver, lymph nodes, spleen and/or kidney. Regardless of whether the CSH was localized or generalized, the vast majority of patients (90%) had an underlying lymphoproliferative or plasma cell disorder, especially multiple myeloma, lymphoplasmacytic lymphoma, or monoclonal gammopathy of undetermined significance. In 7 cases (8.8%), the CSH was associated with a variety of benign disorders, often with an inflammatory background, and no evidence of a clonal lymphoproliferative or plasma cell disorder. Treatment and prognosis varied according to the underlying disease. A classification of CSH based on etiology and/or associated disease and chemical composition of the crystal is proposed, rare non-immunoglobulin variants of CSH are discussed, and a differential diagnosis of other potentially confusing lesions is provided.

Crystal-storing histiocytosis as a cause of symptomatic cardiac mass

Crystal-storing histiocytosis is a rare disorder that is typically associated with low-grade B-cell lymphomas and monoclonal gammopathy. We present a 64-year-old man with a prior history of weakness and weight loss and hematologic evaluation that had revealed immunoglobulin G kappa monoclonal light chains in the serum and negative bone marrow biopsy. He presented with supraventricular tachyarrhythmia and a right atrial mass seen on echocardiogram and excised surgically. Histologically, the tumor was composed of sheets of macrophages infiltrating the atrial myocardium. The histiocytes were filled with multiple needle-shaped, periodic acid-Schiff-negative crystals. These cells and associated plasma cells failed to show clonal light chain restriction by in situ hybridization or immunohistochemistry, and there was no area of lymphoma in the tumor. Ultrastructural examination showed numerous stick-like, trapezoidal, or polygonal dense crystals in the cytoplasm of histiocytes corroborating the diagnosis of crystal-storing histiocytosis. Although rare, crystal-storing histiocytosis should be included in the differential diagnosis of heart masses in patients with hematologic conditions associated with monoclonal gammopathy.

Crystal-storing histiocytosis associated with only one of two consecutive, but genetically unrelated B-cell lymphomas

A localized crystal-storing histiocytosis (CSH) making the underlying marginal zone lymphoma (MZL) hardly discernible microscopically is described. Image analysis of the hyper electron dense crystals localized light microscopically in swollen histiocytic cells exhibited a major equatorial periodicity of 6.6 nm. Rarely, crystals of this type were detected within plasma cells, but were always surrounded by smooth membrane in contrast to Russell bodies. IgM/lambda restriction and VH3-21*02, DH4-17*01, JH4*02 gene usage were detected behind the lesion. Within 26 months, a genetically unrelated lymphoma of CD5-CD20-CD23-positive phenotype with a different VH1-24*01, DH2-21*02, JH2*01 heavy chain rearrangement, but with the same light chain gene usage, was identified without CSH. This might indicate that the unique condition responsible for the crystal formation is likely to rely on the sequence of the first clonally rearranged heavy chain exhibiting much higher CDRIII pI value (6.0) than the average.

Crystal-storing Histiocytosis due to Massive Accumulation of Charcot-Leyden Crystals: A Unique Association Producing Colonic Polyposis in a 78-year-old Woman With Eosinophilic Colitis

Crystal-storing histiocytosis is a rare diagnosis that to date has only been associated with 2 conditions: intracytoplasmic accumulation of crystallized immunoglobulins in patients with lymphoproliferative disorders or plasma cell dyscrasias, and histiocytic accumulations of phagocytosed clofazimine, a drug used to treat lepromatous leprosy. We describe a 78-year-old woman with a past medical history of dermatologic mastocytosis and peripheral eosinophilia who presented with diarrhea and weight loss, and was found at colonoscopy to have polyposis limited to the right and transverse colon. She eventually underwent subtotal colectomy to remove the segment of polyposis. At gross examination, the colonic mucosa contained numerous polyps ranging from 1 to 7 mm which on histologic evaluation proved to represent mucosal and submucosal collections of histiocytes whose cytoplasm was distended by numerous brightly eosinophilic crystals. An intense eosinophilic infiltrate surrounded the histiocyte collections and also mildly involved the intervening colonic mucosa and superficial submucosa. Electron microscopy confirmed the presence of intracytoplasmic material identical to Charcot-Leyden crystals within histiocytes, representing the breakdown products of degranulated eosinophils. This is the first reported case of crystal-storing histiocytosis produced by massive accumulation of Charcot-Leyden crystals in eosinophilic colitis.

Clinical and molecular characteristics of patients with non-amyloid light chain deposition disorders, and outcome following treatment with high-dose melphalan and autologous stem cell transplantation

Light chain deposition disease (LCDD) is caused by a clonal plasma cell disorder in which fragments of monoclonal immunoglobulin light chains form non-fibrillary deposits in various tissues resulting in organ dysfunction. Crystal storing histiocytosis (CSH) is another light chain deposition disorder in which monoclonal light chains form intracytoplasmic crystals. Both are uncommon diseases for which there is limited treatment experience. Between 2003 and 2005, five patients with LCDD and one with CSH were treated at Boston University Medical Center with high-dose melphalan and autologous peripheral blood stem cell transplantation (HDM/SCT). Five of the six patients had predominantly renal involvement, and one patient with LCDD had biopsy-proven deposits in the myocardium. Molecular characterization revealed that the pathologic light chains were kappa in four of the six patients, and sequence analysis revealed unusual germline donor genes and high rates of amino-acid substitutions. One light chain sequence encoded a new potential N-linked glycosylation site, and another showed evidence of antigen selection. All patients are alive and five of the six patients are in complete hematologic remission at a median follow-up of 12 months (range 4-29 months) after HDM/SCT. In our experience, HDM/SCT is a feasible and effective treatment approach for these disorders.

Pulmonary extranodal marginal zone lymphoma with massive crystal storing histiocytosis

We present an incidentally discovered, unusual case of pulmonary bronchial mucosa-associated lymphoid tissue lymphoma associated with massive crystal storing histiocytosis in a 69-year-old woman. The neoplastic process was masked by large numbers of epithelioid and spindled histiocytes containing crystalline material. Histochemical stains showed intracytoplasmic crystals and immunoperoxidase staining confirmed the histiocytic nature of the swollen cells. Electron microscopy demonstrated the characteristic appearance of immunoglobulin crystals. Lymphoepithelial lesions were identified on immunohistochemical staining, compounding suspicions of an underlying lymphoid neoplasm. Molecular studies later revealed a monoclonal B-cell population. The patient had no systemic evidence of a paraproteinemia. Crystal storing histiocytosis is a rare phenomenon in which macrophages accumulate light chain or immunoglobulin crystalline inclusions. The disease may be systemic, or localized as in this case. It is usually associated with the excess production of a monoclonal immunoglobulin, although there have been many case reports without this feature. An overview of crystal storing histiocytosis is given.

A proliferative glomerulonephritis secondary to a monoclonal IgA

A distinct entity mimicking immune-complex-mediated glomerulonephritis characterized by a proliferative glomerulonephritis with monoclonal immunoglobulin G (IgG) deposits recently was described. We now report a case of a 35-year-old woman who presented with sudden onset of edema, proteinuria, hematuria, and hypertension. Renal biopsy showed diffuse endocapillary proliferation, mesangial cellularity, and amorphous material in the mesangium. Immunofluorescence examination showed mesangial and capillary wall staining for IgA (2+), C3 (2+), fibrinogen (2+), and lambda (2+). Congo red stain was negative. Electron microscopy showed mesangial and subendothelial deposits with a paracrystalline lattice-like substructure forming parallel linear arrays. Extensive laboratory evaluation showed a small population of monoclonal plasma cells with lambda restriction. The present case suggests that monoclonal IgA deposits also can cause proliferative glomerulonephritis. However, the presence of paracrystalline deposits in association with monoclonal IgA deposits has not been described previously.

Crystalloid deposits in the kidney. Case Report

Light chain-producing lymphoproliferative disorders such as multiple myeloma are frequently complicated by renal impairment. Typically, the renal biopsy of a patient with renal failure caused by multiple myeloma shows cast nephropathy, but occasionally crystals may be seen. We describe the case of a patient with acute renal failure caused by multiple myeloma in which, on renal and bone marrow biopsy, there were widespread crystalloid deposits. Crystalloid nephropathy is a very rare condition associated with multiple myeloma and other light chain-secreting disorders. An underlying lymphoproliferative disorder should be considered in the differential diagnosis if crystalloid deposits are seen on a renal or other tissue biopsy.

Histiocytes containing immunoglobulin crystals in the urine of a patient with IgA kappa plasmacytoma of the bladder

Exfoliative cytology specimens from patients with plasma cell dyscrasias are rarely diagnostic, though there are reports of neoplastic plasma cells observed in pleural fluid and urine. Immunoglobulin concretions or crystals associated with neoplastic plasma cell populations have been well described. These crystals may be found within plasma cell nuclei or cytoplasm, extracellularly, or within cells of histiocytic lineage where they are presumably derived by phagocytosis. To the best of our knowledge, this is the first report of immunoglobulin crystals within histiocytes in the urine of a patient with plasmacytoma. A 61-year-old male underwent routine cystoscopy and urine collection to evaluate hematuria. The bladder biopsy demonstrated IgA kappa-producing plasmacytoma. Urine cytopsin preparations did not contain plasma cells, but there were histiocytic cells with degenerative nuclei and eccentrically located cytoplasmic spherical refractile hyaline crystals thought to be immunoglobulin crystals. This was supported by immunocytochemical staining.

Proliferative glomerulonephritis with monoclonal IgG deposits: a distinct entity mimicking immune-complex glomerulonephritis

BACKGROUND

Renal disease related to the deposition of monoclonal immunoglobulins containing both heavy and light chains can occur in type 1 cryoglobulinemia, Randall type light and heavy chain deposition disease (LHCDD), and immunotactoid glomerulonephritis. We report a novel phenotype of glomerular injury that does not conform to any of the previously described patterns of glomerular involvement by monoclonal gammopathy.

METHODS

Ten cases of unclassifiable proliferative glomerulonephritis manifesting glomerular monoclonal immunoglobulin G (IgG) deposits were identified retrospectively from the archives of the Renal Pathology Laboratory of Columbia University over the past 3 years (biopsy incidence 0.21%).

RESULTS

The monoclonal immunoglobulins formed granular electron dense deposits in mesangial, subendothelial, and subepithelial sites, mimicking ordinary immune complex-mediated glomerulonephritis and producing a diffuse endocapillary proliferative or membranoproliferative glomerulonephritis. However, by immunofluorescence, the deposits were monoclonal, staining for a single light chain isotype and a single gamma subclass (including two IgG1kappa, one IgG1lambda, one IgG2lambda, four IgG3kappa, and one IgG3lambda). All cases stained for the three constant domains of the gamma heavy chain (CH1, CH2, and CH3), suggesting deposition of a nondeleted immunoglobulin molecule. Tissue fixation of complement was observed in 90% of cases, and 40% of patients had hypocomplementemia. Clinical presentations included renal insufficiency in 80% (mean serum creatinine 2.8 mg/dL, range 0.9 to 8.0), proteinuria in 100% (mean urine protein 5.8 g/day; range 1.9 to 13.0), nephrotic syndrome in 44%, and microhematuria in 60%. A monoclonal serum protein with the same heavy and light chain isotype as that of the glomerular deposits was identified in 50% of cases (including three IgGkappa and two IgGlambda); however, no patient had clinical or laboratory features of type 1 cryoglobulinemia. No patient had overt myeloma or lymphoma at presentation or over the course of follow-up (mean 12 months).

CONCLUSION

Glomerular deposition of monoclonal IgG can produce a proliferative glomerulonephritis that mimics immune-complex glomerulonephritis by light and electron microscopy. Proper recognition of this entity requires confirmation of monoclonality by staining for the gamma heavy chain subclasses.

Metachronous Development of Nonamyloidogenic λ Light Chain Deposition Disease and IgG Heavy Chain Amyloidosis in the Same Patient

We report a highly unusual case of monoclonal immunoglobulin deposition disease-associated nephrotic syndrome in which a patient developed both lambda light chain deposition disease and 6 years afterward IgG-heavy chain amyloidosis. The patient initially underwent autologous peripheral blood stem cell transplantation as treatment of the underlying plasma cell dyscrasia causing the light chain deposition disease-related nephrotic syndrome. After 6 years of clinical remission, recurrence of the nephrotic syndrome led to a renal biopsy demonstrating IgG-heavy chain amyloidosis. Interestingly, much of the characteristic nodular glomerular sclerosis seen in light chain deposition disease regressed between the time of the first biopsy and the second. Given the length of time between the development of the two diseases and the apparent success of stem cell transplantation in treating the first, we think that the patient produced two distinctly different abnormal plasma cell clones. To our knowledge, this is the first report of two different monoclonal immunoglobulin deposition diseases occurring in the same patient.

Pulmonary crystal-storing histiocytosis and extranodal marginal zone B-cell lymphoma associated with a fibroleiomyomatous hamartoma

Crystal-storing histiocytosis (CSH) is a rare disorder occurring in patients with lymphoproliferative diseases, predominantly in cases of multiple myeloma and low-grade B-cell lymphoma. To the best of our knowledge, only three cases of pulmonary CSH have been reported in the English literature and one of them was associated with a low-grade B-cell lymphoma (immunocytoma). We document a case of a 59-year-old man with bilateral lung masses in which a right middle lobe pulmonary lobectomy specimen showed CSH associated with an extranodal marginal-zone B-cell lymphoma. A single nodule showing features of fibroleiomyomatous hamartoma was present in a wedge biopsy specimen from the left lung. Two nodules within the right middle lobe were composed of sheets of histiocytic cells with abundant eosinophilic cytoplasm resembling striated muscle cells. In addition, there were nodular aggregates and a more diffuse infiltrate of small slightly atypical centrocyte-like lymphocytes, as well as bronchial lymphoepithelial lesions. Immunohistochemistry performed on paraffin-embedded sections demonstrated that the histiocytic cells were immunoreactive with the KP-1 (CD68) antibody while the lymphocytic infiltrate was CD20 positive, co-expressed for CD43, and was negative for CD3, CD5, and CD10. Genotypic analysis demonstrated the presence of an immunoglobulin heavy-chain gene rearrangement, indicating the presence of a monoclonal B-cell population. These features were consistent with pulmonary CSH associated with extranodal marginal-zone lymphoma of baltoma type.