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

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.

Histiocytic Glomerulopathy With Noncrystalline Inclusion Associated With IgG-Kappa Plasma Cell Dyscrasia

The kidney pathology of monoclonal gammopathy of renal significance varies greatly. In this report, we present a woman in her 20s with nephrotic syndrome and monoclonal immunoglobulin G kappa (serum and urine) without diabetes. She had a family history of nephrotic syndrome as well as hematologic and connective tissue disorders. A kidney biopsy showed nodular glomerulosclerosis, with the glomerular capillary full of histiocytes, which were strongly positive for kappa, not lambda. Immunoelectron microscopy revealed that histiocytes had infiltrated the glomerular subendothelial space, and enlarged lysosomes of histiocytes contained kappa light chains, without apparent crystalline formation. Bone marrow examination was negative for malignancy; thus, we diagnosed this case as histiocytic glomerulopathy with noncrystalline inclusion associated with immunoglobulin G-kappa plasma cell dyscrasia. Hematologic treatment with bortezomib and daratumumab decreased her level of serum kappa chain and proteinuria. Two years after diagnosis, her kidney function remained normal, urinary protein level decreased to 1 g/d, and free light-chain ratio decreased to 3.1.

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.

Monoclonal Gammopathy-Related Kidney Diseases

Monoclonal gammopathies occur secondary to a broad range of clonal B lymphocyte or plasma cell disorders, producing either whole or truncated monoclonal immunoglobulins. The kidneys are often affected by these monoclonal proteins, and, although not mutually exclusive, can involve the glomeruli, tubules, interstitium, and vasculature. The nephrotoxic potential of these monoclonal proteins is dependent on a variety of physicochemical characteristics that are responsible for the diverse clinicopathologic manifestations, including glomerular diseases with organized deposits, glomerular diseases with granular deposits, and other lesions, such as C3 glomerulopathy and thrombotic microangiopathy with unique pathophysiologic features. The diseases that involve primarily the tubulointerstitial and vascular compartments are light chain cast nephropathy, light chain proximal tubulopathy, crystal-storing histiocytosis, and crystalglobulin-induced nephropathy with distinct acute and chronic clinicopathologic features. The diagnosis of a monoclonal gammopathy-related kidney disease is established by identification of an underlying active or more commonly, low-grade hematologic malignancy, serologic evidence of a monoclonal gammopathy when detectable, and most importantly, monoclonal protein-induced pathologic lesions seen in a kidney biopsy, confirming the association with the monoclonal protein. Establishing a diagnosis may be challenging at times, particularly in the absence of an overt hematologic malignancy, with or without monoclonal gammopathy, such as proliferative glomerulonephritis with monoclonal immunoglobulin deposits. Overall, the treatment is directed against the underlying hematologic disorder and the potential source of the monoclonal protein.

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.

Combined light chain crystalline tubulopathy, podocytopathy, and histiocytosis associated with Bence-Jones κ protein diagnosed via immuno-electron microscopy

We herein report a case of a combined crystalline light chain tubulopathy, podocytopathy, histiocytosis, and cast nephropathy in a patient with monoclonal gammopathy of renal significance (MGRS). A 66-year-old female with impaired renal function was referred to our department. Despite intravenous fluid resuscitation, the kidney function worsened progressively; thus, a kidney biopsy was performed. The kidney biopsy revealed light chain proximal tubulopathy (LCPT) with crystals, light chain crystal podocytopathy (LCCP), crystal-storing histiocytosis (CSH), and light chain cast nephropathy (LCCN). Of note, LCCP and CSH were diagnosed via electron microscopy. Serum and urine immunoelectrophoresis (IEP) revealed the presence of monoclonal Bence-Jones protein and free κ light chains. Bone marrow aspiration showed < 10% plasma cell proliferation. Thus, we had encountered a rare case in which a variety of kidney lesions were combined with MGRS. Most of the LCPT, LCCP, and CSH cases show monoclonal IgG κ, while our case showed Bence-Jones protein κ.

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.