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Proliferative Glomerulonephritis With Monoclonal IgG1κ Deposits in a Hepatitis C Virus–Positive Patient
Kidney Biopsy Teaching Case Proliferative Glomerulonephritis With Monoclonal IgG1k Deposits in a Hepatitis C Virus–Positive Patient Jessica Hemminger, MD,1,* Madhu Kandarpa, MD,2,* Arthur Tsai, MD,2 and Tibor Nadasdy, MD 1 Hepatitis C virus infection is associated with several glomerular diseases, most commonly cryoglobulinemic glomerulonephritis, which is typically secondary to type II mixed cryoglobulinemia. We present a patient with hepatitis C virus infection and cryoglobulinemic glomerulonephritis secondary to type I (monoclonal) cryoglobulinemia that is likely related to a concurrent hepatitis C virus infection–associated lymphoproliferative disorder. We list the differential diagnosis of cryoglobulinemic glomerulonephritis. Additionally, the case draws attention to the possibility that, rarely, even clinically undetectable “occult” B-cell lymphoproliferative disorders may result in significant kidney disease. Am J Kidney Dis. 67(4):703-708. ª 2016 by the National Kidney Foundation, Inc. INDEX WORDS: Proliferative glomerulonephritis; monoclonal IgG deposits; hepatitis C virus (HCV); cryoglobulinemia; occult B cell lymphoproliferative disorder; kidney biopsy.
INTRODUCTION Hepatitis C virus (HCV) infection is associated with several glomerular diseases, most commonly cryoglobulinemic glomerulonephritis (GN).1-3 Other glomerular diseases, such as membranoproliferativetype GN without cryoglobulin deposits and membranous nephropathy, are less frequent. Cryoglobulinemic GN associated with HCV infection is usually secondary to type II cryoglobulinemia (“mixed” with monoclonal immunoglobulin Mk [IgMk] rheumatoid factor and polyclonal IgG), but HCV can also induce type III cryoglobulinemia (mixed with polyclonal IgM and IgG). HCV infection is not directly associated with type I (monoclonal) cryoglobulinemia. We present an HCV-infected patient who developed symptoms of GN with kidney biopsy findings entirely consistent with cryoglobulinemic GN. However, further workup indicated that the cryoglobulins were type I.
CASE REPORT Clinical History and Initial Laboratory Data The patient is a 48-year-old white woman with a history of mild hypertension, HCV infection diagnosed 8 years prior, normal kidney function, and body mass index of 24.5 kg/m2. She is HIV (human immunodeficiency virus) and hepatitis B virus negative. A liver biopsy showed minimally active chronic hepatitis with mild portal fibrosis, and she was started on weekly subcutaneous pegylated interferon alfa, 100 mg. A year later, she developed nephrotic syndrome, erythematous skin lesions exacerbated by cold exposure, and glomerular filtration rate loss evident by an increased serum creatinine level. See Table 1 for laboratory data. Computed tomography of the pelvis and abdomen showed slightly enlarged hilar, iliac, and inguinal lymph nodes. A kidney biopsy was performed.
Kidney Biopsy Up to 33 glomeruli per section were available for light microscopic examination; only 1 was obsolescent. Glomeruli were Am J Kidney Dis. 2016;67(4):703-708
enlarged with moderate to prominent intracapillary hypercellularity, large glassy wire loop–like glomerular capillary deposits, and occasional intracapillary hyaline thrombi (Fig 1A). Crescents were not seen. There was patchy dense interstitial mononuclear cell infiltrate admixed with plasma cells that was primarily at the corticomedullary junction and focally involved extrarenal fibroadipose tissue (Fig 1B). Immunohistochemical staining for CD3, CD20, and CD68 indicated that the mononuclear cell infiltrate was composed mostly of a mixture of small mature T and B cells with admixed histiocytes, and there were a few small clusters of B cells. The k and l light chain immunohistochemistry demonstrated a k-restricted plasma cell population. There was no coexpression of CD5, BCL1, CD10, or CD43 on B cells. Interstitial fibrosis and tubular atrophy were mild, and arteries contained mild fibrointimal thickening. Frozen sections cut for immunofluorescence contained 6 glomeruli. There was prominent diffuse granular to smudgy mesangial and glomerular capillary staining, including intracapillary globules, for IgG and k light chain (Fig 2). No glomerular staining was noted for IgA, IgM, or l light chain. Direct immunofluorescence with antibodies to the IgG subclasses showed that glomerular deposits stained for IgG1 only. The deposits also stained moderately for C1q and weakly for C3. A focal infiltrate of mononuclear cells at the corticomedullary junction stained for IgG1 and k light chain, but not for l light chain (Fig 3). Ultrastructurally, abundant discrete deposits were identified in the mesangium and along the glomerular capillary loops. Glomerular capillary deposits were mainly subendothelial. A few glomerular intramembranous and subepithelial deposits were also noted. On higher magnification, glomerular deposits showed a distinct
From the 1Department of Pathology, The Ohio State University, Columbus, OH; and 2Kidney Care Specialists, LLC, Kettering, OH. * J.H. and M.K. contributed equally to the manuscript. Received August 15, 2015. Accepted in revised form October 8, 2015. Originally published online November 21, 2015. Address correspondence to Tibor Nadasdy, MD, The Ohio State University, M018 Starling-Loving Hall, 320 W 10th Ave, Columbus, OH 43210. E-mail: [email protected] 2016 by the National Kidney Foundation, Inc. 0272-6386 http://dx.doi.org/10.1053/j.ajkd.2015.08.032 703
Hemminger et al Table 1. Laboratory Data Before Kidney Biopsy
Scr, mg/dL eGFR,a mL/min/1.73 m2 Proteinuria
1.3 46 9 g/24h
Serum albumin, g/dL Urinalysis, RBCs/HPF WBC count, 3103/mL Platelet count, 3103/mL Hemoglobin, g/dL Hematocrit, % C3,c mg/dL C4,c mg/dL HCV load LFTs Rheumatoid factor Serum cryoglobulins ANA SPEP & UPEP
1.7 5-10 1.9-2.7 59-107 9.1 27 40 4 Undetectable Normal
— —
Negative No monoclonal protein
After Kidney Biopsy
0.85 76 3 weeks: 3.2b; 3 months: 0.2b
— —
Reference Reference Reference Reference
— —
Undetectable
—
Negative 2%
—
No monoclonal protein
Note: Conversion factor for Scr in mg/dL to mmol/L, 388.4. Abbreviations: ANA, antinuclear antibody; eGFR, estimated glomerular filtration rate; HCV, hepatitis C virus; LFTs, liver function tests; RBCs/HPF: red blood cells/high-power field; Scr, serum creatinine; SPEP, serum protein electrophoresis; UPEP, urine protein electrophoresis; WBC, white blood cell. a Calculated using the 4-variable MDRD (Modification of Diet in Renal Disease) Study equation. b Spot urine protein-creatinine ratio. c No prior levels for comparison.
substructure consisting of paracrystalline material with fibrillar/ vaguely microtubular structure in a parallel arrangement (Fig 4). The diameter of the microtubules was 12.2 nm. Scattered endothelial tubuloreticular inclusions were noted. Foot-process effacement was widespread. Extraglomerular deposits were not seen. The paraffin block containing the kidney biopsy specimen underwent immunoglobulin heavy chain gene rearrangement studies, which detected a monoclonal B-cell population.
Diagnosis 1. Active diffuse intracapillary proliferative glomerulonephritis with large glomerular capillary IgG1k-positive deposits with
paracrystalline substructure, consistent with type I cryoglobulinemia-associated glomerulonephritis. 2. Focal involvement of kidney parenchyma by a low-grade B-cell lymphoproliferative disorder (BLPD) with plasmacytic differentiation and IgG1k-restricted staining.
Clinical Follow-up The patient was immediately started on 500 mg/d of methylprednisolone followed by 100 mg/d of prednisone. The prednisone dosage was gradually tapered to 10 mg/d and stopped after 6 months. Kidney function normalized, proteinuria decreased, and pancytopenia resolved. A serum cryoglobulin test (cryocrit) indicated low levels (2%) of cryoglobulin. See Table 1 for additional laboratory data. A subsequent bone marrow biopsy did not show evidence of a lymphoproliferative disorder. Flow cytometry was unremarkable. Positron emission tomography (10 days after kidney biopsy) showed scattered mediastinal, pelvic, and inguinal lymph nodes up to 1 cm in diameter and a larger 3.4-cm right external iliac lymph node. Computed tomography performed 3 months later was negative for lymphadenopathy.
DISCUSSION In the case presented, the findings are consistent with cryoglobulinemic GN due to type 1 (IgG1k) cryoglobulinemia. The monoclonal cryoglobulinemia is unlikely to be directly related to HCV infection and is probably secondary to an underlying BLPD, which is supported by focal involvement of kidney parenchyma by a low-grade BLPD with plasmacytic differentiation. The diagnosis and classification of cryoglobulinemic GN is not always straightforward. The glomerular morphology can be variable from almost normal glomeruli to prominent glomerular intracapillary hypercellularity with cryoglobulin precipitates (“hyalin thrombi”).1 Crescents are rarely seen. There is not always obvious staining by immunofluorescence because the glomerular cryoglobulin deposits can be transient and focal in distribution. Table 2 lists the characteristic findings distinguishing types I, II, and III cryoglobulinemia. It is difficult to detect type III cryoglobulins in kidney biopsy specimens because the cryoglobulin is polyclonal and
Figure 1. Light microscopy findings. (A) Hypercellular glomerulus with many thickened glomerular capillary loops and occasional intracapillary hyaline thrombi (arrows). (B) Focal dense mononuclear cell infiltrate at the corticomedullary junction (hematoxylin and eosin stain; original magnifications, A, 3600; B, 3100). 704
Am J Kidney Dis. 2016;67(4):703-708
Glomerulonephritis With Monoclonal Deposits
Figure 2. Strong glomerular mesangial and capillary loop staining was seen for immunoglobulin G (IgG), but not for IgA or IgM. The deposits were k (K) light chain-restricted (direct immunofluorescence; original magnification, 3400). Abbreviation: L, lambda.
the deposits typically do not have a substructure. In type I cryoglobulinemia, there is deposition of monoclonal immunoglobulin, commonly IgG. In our experience, the deposits rarely have the characteristic microtubular substructure seen in type II cryoglobulinemia, but frequently have a crystalline/paracrystalline substructure with parallel arrangement of fibrils or microtubules or a fine periodicity in angularshaped crystalline-type deposits.4-6
Considering the paracrystalline substructure and monoclonal nature of the deposits in the case presented, a diagnosis of immunotactoid GN was considered. Originally, it was proposed that cases with underlying cryoglobulinemia, hematologic disorders, or systemic lupus erythematosus should be excluded as immunotactoid GNs, but cases of fibrillary GN were to be included.7 Fibrillary GN is now considered by most to be a separate entity distinct from
Figure 3. There was a focal dense mononuclear cell infiltrate in the frozen section that demonstrated staining for immunoglobulin G1 (IgG1) and k (K) light chain only (direct immunofluorescence; original magnification, 3200.) Abbreviation: L, lambda. Am J Kidney Dis. 2016;67(4):703-708
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Figure 4. Electron microscopy findings. (A) The mainly subendothelial deposits had distinct fibrillary substructure. Fibrils were localized to the deposits only; randomly arranged fibrillary material was not seen within the glomerular basement membrane or in the mesangial matrix (uranyl acetate–lead citrate; original magnification, 340,000). (B) Higher magnification of fibrils shows vaguely microtubular structure with a mean diameter of 12.2 nm (uranyl acetate–lead citrate; original magnification, 3150,000).
immunotactoid GN, and it is recognized that many cases of immunotactoid GN are associated with a BLPD or monoclonal gammopathy of undetermined significance.4-6 Despite the microtubular substructure of type II cryoglobulin deposits, cryoglobulinemic GN due to type II cryoglobulins is not considered an immunotactoid GN. In type I cryoglobulinemia, the issue is less settled because the cryoglobulinemic properties of monoclonal immunoglobulins may not always be evident clinically. It is likely that many cases diagnosed as immunotactoid GN represent monoclonal immunoglobulin deposits with cryoglobulin properties even if circulating monoclonal immunoglobulins are undetectable. Additional
glomerular diseases considered in the differential diagnosis are listed in Table 3. Laboratory testing for cryoglobulinemia can be useful; however, it can occasionally be misleading if the specimen is handled inappropriately.8 Therefore, a negative cryoglobulin test result should be interpreted with caution if there is strong clinical suspicion for cryoglobulinemia. Of note, it is useful to order both quantitative (cryoglobulin/cryocrit test) and qualitative (immunodiffusion and immunofixation) testing to sufficiently evaluate the amount of cryoglobulins, as well as to identify the cryoglobulin type. Rheumatoid factor (IgMk) is positive in type II cryoglobulinemia. Given that type I cryoglobulinemia is frequently IgG, a
Table 2. Characteristic Findings in Cryoglobulinemic GN Cryoglobulin Type I
Glomerular hypercellularity Glomerular capillary hyalin thrombi, large deposits Vasculitis in the kidney biopsy Distribution of deposits IgG in deposits IgM in deposits Substructure in deposits Rheumatoid factor Monoclonal spike in serum Low serum C3 Low serum C4 HCV infection Other infection, acute inflammation, autoimmune disease, malignancy BLPD
II
III
111 1
111 11
11 1/2
2 Diffuse, global Monoclonal (if IgG) Monoclonal (if IgM) Paracrystalline/crystalline 1/2 (if IgM) 11 1/2 1/2 2 2
1 Can be focal, segmental 111 (polyclonal) 111 (IgMk) Microtubular (20-30 nm) 111 1/2 1/2 111 111 1/2
1/2 Diffuse, global 11 to 111 (polyclonal) 11 to 111 (polyclonal) Usually none 11 2 11 11 1 11
11
2
2
Abbreviations: BLPD, B-cell lymphoproliferative disorder; HCV, hepatitis C virus; IgG, immunoglobulin G; GN, glomerulonephritis. 706
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Glomerulonephritis With Monoclonal Deposits Table 3. Morphologic Differential Diagnosis of Cryoglobulinemic GN
Cryoglobulinemic GN, type I Cryoglobulinemic GN, types II/III
Histologya
IFa
EMa
MPGN pattern with “wire loop” lesions or hyaline thrombi MPGN pattern with “wire loop” lesions or hyaline thrombi
Monoclonal IgG or IgM
Mesangial and subendothelial crystalline/paracrystalline deposits Mesangial and subendothelial electron-dense deposits; type II typically has microtubular substructure (20-30 nm) Mesangial and subendothelial electron-dense deposits with possible substructure; duplication of GBM Mesangial, subendothelial, and/or subepithelial electron-dense deposits; can have fingerprint-like substructure Microtubular or organized paracrystalline deposits in mesangium and along GBM (commonly subendothelial) Randomly arranged fibrils (10-20 nm) in mesangium and along GBM; not microtubular Mostly mesangial and subendothelial with occasional subepithelial electron-dense deposits; no substructure
IgM and IgG with both k and l light chain
MPGN associated with HCV infection
MPGN pattern without “wire loop” lesions or hyaline thrombi
Polyclonal IgG and IgM
Diffuse proliferative lupus nephritis
Endocapillary proliferation and/or “wire loop” lesions or hyaline thrombi
Polyclonal IgG; fullhouse pattern
Immunotactoid GN
Variable: MPGN pattern, mesangial expansion/ hypercellularity
Commonly monoclonal (IgG predominant)
Fibrillary GN
Variable: mesangial expansion, MPGN pattern, membranous pattern MPGN pattern . endocapillary proliferation pattern . membranous pattern
Polyclonal IgG; IgG1 and IgG4
PGNMIGD
Monoclonal IgG (mostly IgG3k)
Clinical Associations
BLPD, MGUS
Infection (HBV and HCV), autoimmune disorder
HCV infection
SLE
BLPD, MGUS, absence of type II and III cryoglobulinemias Rarely malignancy, dysproteinemia, autoimmune disorder, HCV infection23 MGUS in 30% of cases
Abbreviations: BLPD, B-cell lymphoproliferative disorder; EM, electron microscopy; GBM, glomerular basement membrane; GN, glomerulonephritis; HBV, hepatitis B virus; HCV, hepatitis C virus; IF, immunofluorescence; IgG, immunoglobulin G; MGUS, monoclonal gammopathy of undetermined significance; MPGN, membranoproliferative glomerulonephritis; PGNMIGD, proliferative glomerulonephritis with monoclonal IgG deposits; SLE, systemic lupus erythematosus. a Glomerular findings.
positive cryoglobulin test with a negative rheumatoid factor test result is suggestive of type I cryoglobulinemia. In type III cryoglobulinemia, rheumatoid factor, if present, is polyclonal. In our patient, the type I cryoglobulinemia was likely secondary to an underlying low-grade BLPD. It is well established that chronic HCV infection can be associated with atypical lymphoid proliferations, including B-cell lymphomas.9,10 Furthermore, HCV infection–associated BLPDs include monoclonal Bcell populations in peripheral blood, bone marrow, and other tissues without clinical evidence of lymphoma.10 In many cases of HCV infection–associated BLPDs, successful treatment and elimination of the HCV will result in regression of the lymphoma. The mechanism underlying the association between HCV and BLPDs appears to be a multistep and multifactorial process involving both genetic and environmental factors.11-13 Similar to gastric lymphomagenesis associated with Helicobacter pylori infections, chronic stimulation of B cells by HCV likely plays a large role. Additionally, the acquisition of multiple genetic alterations, such as Am J Kidney Dis. 2016;67(4):703-708
t(14;18) (ie, a translocation involving chromosomes 14 and 18) and BCL2 overexpression, favor B-cell survival and proliferation, promoting expansion of abnormal B-cell clones. Of note, HCV can directly infect peripheral-blood mononuclear cells, which could also be a contributing factor in the development of abnormal B-cell populations.14 In our patient, although an overt lymphoma was not detected, the monoclonal B-cell population detected in the biopsy likely represents an HCV infection–associated BLPD. It is possible that the steroid therapy the patient received as treatment for the GN was also effective in eliminating the BLPD. Although there have been recent advances in terms of targeted therapies, steroids remain a component of many frontline treatment regimens for low- and high-grade B-cell lymphomas, as well as plasma cell neoplasms.15-18 It is important to note that monoclonal B-cell populations without overt evidence of lymphoma have also been reported in the absence of HCV infection. Most commonly, monoclonal B-cell populations circulating in peripheral blood without evidence of 707
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lymphoma or meeting the criteria for chronic lymphocytic leukemia, termed monoclonal B-cell lymphocytosis, have been reported in up to 10% of adults older than 60 years using high-sensitivity flow cytometry.19 The vast majority of patients with a monoclonal B-cell lymphocytosis do not progress to clinical disease. Similar monoclonal B-cell populations without overt lymphoma can be detected in bone marrow specimens and rarely, extramedullary tissue biopsy specimens.19-21 Furthermore, indolent lymphomas can be detected incidentally in lymph node dissections performed for other reasons.19 Many incidental lymphomas are not associated with systemic dissemination, show only partial nodal involvement, and/or frequently do not require treatment, suggesting that it is possible to have only minimal/isolated involvement by an indolent lymphoma. Also, rarely, monotypic B-cell expansions can occur in reactive lymphoid proliferations.20 In summary, our case demonstrates that the correct diagnosis and typing of cryoglobulinemic GN can be difficult, even if the cryoglobulinemia appears to be associated with HCV infection. Also, our case draws attention to the possibility that, rarely, clinically undetectable “occult” BLPDs, which frequently lack a monoclonal gammopathy and bone marrow involvement, may result in significant kidney disease, similar to the occurrence of monoclonal immunoglobulin deposition disease or AL amyloidosis in patients without an overt plasma cell neoplasm. Thus, in the setting of an atypical B-cell infiltrate or in kidney diseases that can be associated with lymphoproliferative diseases, B-cell clonality studies should be a consideration. However, even in the setting of a monoclonal B-cell population, overall morphologic and clinical findings should be considered before rendering a diagnosis of lymphoma because there appear to be differences in disease behavior between occult BLPDs and typical B-cell lymphomas.22
ACKNOWLEDGEMENTS Support: None. Financial Disclosure: The authors declare that they have no relevant financial interests. Peer Review: Evaluated by an external peer reviewer, the Pathology Editor, the Education Editor, and the Editor-in-Chief.
REFERENCES 1. D’Amico G. Renal involvement in hepatitis C infection: cryoglobulinemic glomerulonephritis. Kidney Int. 1998;54: 650-671. 2. Fabrizi F, Plaisier E, Saadoun D, Martin P, Messa P, Cacoub P. Hepatitis C virus infection, mixed cryoglobulinemia, and kidney disease. Am J Kidney Dis. 2013;61:623-637. 3. Alpers CE, Smith KD. Cryoglobulinemia and renal disease. Curr Opin Nephrol Hypertens. 2008;17:243-249.
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4. Rosenstock JL, Markowitz GS, Valeri AM, Sacchi G, Appel GB, D’Agati VD. Fibrillary and immunotactoid glomerulonephritis: distinct entities with different clinical and pathologic features. Kidney Int. 2003;63:1450-1461. 5. Herrera GA, Turbat-Herrera EA. Renal diseases with organized deposits: an algorithmic approach to classification and clinicopathologic diagnosis. Arch Pathol Lab Med. 2010;134: 512-531. 6. Nasr SH, Fidler ME, Cornell LD, et al. Immunotactoid glomerulopathy: clinicopathologic and proteomic study. Nephrol Dial Transplant. 2012;27:4137-4146. 7. Schwartz MM, Korbet SM, Lewis EJ. Immunotactoid glomerulopathy. J Am Soc Nephrol. 2002;13:1390-1397. 8. Motyckova G, Murali M. Laboratory testing for cryoglobulins. Am J Hematol. 2011;86:500-502. 9. Paydas S. Hepatitis C virus and lymphoma. Crit Rev Oncol Hematol. 2015;93:246-256. 10. Mollejo M, Menarguez J, Guisado-Vasco P, et al. Hepatitis C virus-related lymphoproliferative disorders encompass a broader clinical and morphological spectrum than previously recognized: a clinicopathological study. Mod Pathol. 2014;27: 281-293. 11. Ferri C, Zignego AL, Pileri SA. Cryoglobulins. J Clin Pathol. 2002;55:4-13. 12. Ferri C, Sebastiani M, Giuggioli D, et al. Hepatitis C virus syndrome: a constellation of organ- and non-organ specific autoimmune disorders, B-cell non-Hodgkin’s lymphoma, and cancer. World J Hepatol. 2015;7:327-343. 13. Forghieri F, Luppi M, Barozzi P, et al. Pathogenetic mechanisms of hepatitis C virus-induced B-cell lymphomagenesis. Clin Dev Immunol. 2012;2012:807351. 14. Zignego AL, Macchia D, Monti M, et al. Infection of peripheral mononuclear blood cells by hepatitis C virus. J Hematol. 1992;15:382-386. 15. Lunning MA, Vose JM. Management of indolent lymphoma: where are we now and where are we going. Blood Rev. 2012;26:279-288. 16. Armitage JO. My treatment approach to patients with diffuse large B-cell lymphoma. Mayo Clinic Proc. 2012;87: 161-171. 17. Rajkumar SV. Multiple myeloma: 2012 update on diagnosis, risk-stratification, and management. Am J Hematol. 2012;87:78-88. 18. McKay LI, Cidlowski JA. Corticosteroids in the treatment of neoplasms. In: Holland-Frei Cancer Medicine. 6th ed. Hamilton, ON, Canada: BC Decker. http://www.ncbi.nlm.nih.gov/ books/NBK13383/. Accessed July 9, 2015. 19. Rawstron AC. Occult B-cell lymphoproliferative disorders. Histopathology. 2011;58:81-89. 20. Kussick SJ, Kalnoski M, Braziel RM, Wood BL. Prominent clonal B-cell populations identified by flow cytometry in histologically reactive lymphoid proliferations. Am J Clin Pathol. 2004;121:464-472. 21. Nelson BP, Abdul-Nabi A, Goolsby C, Winter J, Peterson L. Characterization of tissue findings in bone marrow biopsy specimens with small monoclonal B-cell populations. Am J Clin Pathol. 2014;141:687-696. 22. Kroft SH. Monoclones, monotypes, and neoplasia pitfalls in lymphoma diagnosis. Am J Clin Pathol. 2004;121:457-459. 23. Nasr SH, Valeri AM, Cornell LD, et al. Fibrillary glomerulonephritis: a report of 66 cases from a single institution. Clin J Am Soc Nephrol. 2011;6:775-784.
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INTRODUCTION Hepatitis C virus (HCV) infection is associated with several glomerular diseases, most commonly cryoglobulinemic glomerulonephritis (GN).1-3 Other glomerular diseases, such as membranoproliferativetype GN without cryoglobulin deposits and membranous nephropathy, are less frequent. Cryoglobulinemic GN associated with HCV infection is usually secondary to type II cryoglobulinemia (“mixed” with monoclonal immunoglobulin Mk [IgMk] rheumatoid factor and polyclonal IgG), but HCV can also induce type III cryoglobulinemia (mixed with polyclonal IgM and IgG). HCV infection is not directly associated with type I (monoclonal) cryoglobulinemia. We present an HCV-infected patient who developed symptoms of GN with kidney biopsy findings entirely consistent with cryoglobulinemic GN. However, further workup indicated that the cryoglobulins were type I.
CASE REPORT Clinical History and Initial Laboratory Data The patient is a 48-year-old white woman with a history of mild hypertension, HCV infection diagnosed 8 years prior, normal kidney function, and body mass index of 24.5 kg/m2. She is HIV (human immunodeficiency virus) and hepatitis B virus negative. A liver biopsy showed minimally active chronic hepatitis with mild portal fibrosis, and she was started on weekly subcutaneous pegylated interferon alfa, 100 mg. A year later, she developed nephrotic syndrome, erythematous skin lesions exacerbated by cold exposure, and glomerular filtration rate loss evident by an increased serum creatinine level. See Table 1 for laboratory data. Computed tomography of the pelvis and abdomen showed slightly enlarged hilar, iliac, and inguinal lymph nodes. A kidney biopsy was performed.
Kidney Biopsy Up to 33 glomeruli per section were available for light microscopic examination; only 1 was obsolescent. Glomeruli were Am J Kidney Dis. 2016;67(4):703-708
enlarged with moderate to prominent intracapillary hypercellularity, large glassy wire loop–like glomerular capillary deposits, and occasional intracapillary hyaline thrombi (Fig 1A). Crescents were not seen. There was patchy dense interstitial mononuclear cell infiltrate admixed with plasma cells that was primarily at the corticomedullary junction and focally involved extrarenal fibroadipose tissue (Fig 1B). Immunohistochemical staining for CD3, CD20, and CD68 indicated that the mononuclear cell infiltrate was composed mostly of a mixture of small mature T and B cells with admixed histiocytes, and there were a few small clusters of B cells. The k and l light chain immunohistochemistry demonstrated a k-restricted plasma cell population. There was no coexpression of CD5, BCL1, CD10, or CD43 on B cells. Interstitial fibrosis and tubular atrophy were mild, and arteries contained mild fibrointimal thickening. Frozen sections cut for immunofluorescence contained 6 glomeruli. There was prominent diffuse granular to smudgy mesangial and glomerular capillary staining, including intracapillary globules, for IgG and k light chain (Fig 2). No glomerular staining was noted for IgA, IgM, or l light chain. Direct immunofluorescence with antibodies to the IgG subclasses showed that glomerular deposits stained for IgG1 only. The deposits also stained moderately for C1q and weakly for C3. A focal infiltrate of mononuclear cells at the corticomedullary junction stained for IgG1 and k light chain, but not for l light chain (Fig 3). Ultrastructurally, abundant discrete deposits were identified in the mesangium and along the glomerular capillary loops. Glomerular capillary deposits were mainly subendothelial. A few glomerular intramembranous and subepithelial deposits were also noted. On higher magnification, glomerular deposits showed a distinct
From the 1Department of Pathology, The Ohio State University, Columbus, OH; and 2Kidney Care Specialists, LLC, Kettering, OH. * J.H. and M.K. contributed equally to the manuscript. Received August 15, 2015. Accepted in revised form October 8, 2015. Originally published online November 21, 2015. Address correspondence to Tibor Nadasdy, MD, The Ohio State University, M018 Starling-Loving Hall, 320 W 10th Ave, Columbus, OH 43210. E-mail: [email protected] 2016 by the National Kidney Foundation, Inc. 0272-6386 http://dx.doi.org/10.1053/j.ajkd.2015.08.032 703
Hemminger et al Table 1. Laboratory Data Before Kidney Biopsy
Scr, mg/dL eGFR,a mL/min/1.73 m2 Proteinuria
1.3 46 9 g/24h
Serum albumin, g/dL Urinalysis, RBCs/HPF WBC count, 3103/mL Platelet count, 3103/mL Hemoglobin, g/dL Hematocrit, % C3,c mg/dL C4,c mg/dL HCV load LFTs Rheumatoid factor Serum cryoglobulins ANA SPEP & UPEP
1.7 5-10 1.9-2.7 59-107 9.1 27 40 4 Undetectable Normal
— —
Negative No monoclonal protein
After Kidney Biopsy
0.85 76 3 weeks: 3.2b; 3 months: 0.2b
— —
Reference Reference Reference Reference
— —
Undetectable
—
Negative 2%
—
No monoclonal protein
Note: Conversion factor for Scr in mg/dL to mmol/L, 388.4. Abbreviations: ANA, antinuclear antibody; eGFR, estimated glomerular filtration rate; HCV, hepatitis C virus; LFTs, liver function tests; RBCs/HPF: red blood cells/high-power field; Scr, serum creatinine; SPEP, serum protein electrophoresis; UPEP, urine protein electrophoresis; WBC, white blood cell. a Calculated using the 4-variable MDRD (Modification of Diet in Renal Disease) Study equation. b Spot urine protein-creatinine ratio. c No prior levels for comparison.
substructure consisting of paracrystalline material with fibrillar/ vaguely microtubular structure in a parallel arrangement (Fig 4). The diameter of the microtubules was 12.2 nm. Scattered endothelial tubuloreticular inclusions were noted. Foot-process effacement was widespread. Extraglomerular deposits were not seen. The paraffin block containing the kidney biopsy specimen underwent immunoglobulin heavy chain gene rearrangement studies, which detected a monoclonal B-cell population.
Diagnosis 1. Active diffuse intracapillary proliferative glomerulonephritis with large glomerular capillary IgG1k-positive deposits with
paracrystalline substructure, consistent with type I cryoglobulinemia-associated glomerulonephritis. 2. Focal involvement of kidney parenchyma by a low-grade B-cell lymphoproliferative disorder (BLPD) with plasmacytic differentiation and IgG1k-restricted staining.
Clinical Follow-up The patient was immediately started on 500 mg/d of methylprednisolone followed by 100 mg/d of prednisone. The prednisone dosage was gradually tapered to 10 mg/d and stopped after 6 months. Kidney function normalized, proteinuria decreased, and pancytopenia resolved. A serum cryoglobulin test (cryocrit) indicated low levels (2%) of cryoglobulin. See Table 1 for additional laboratory data. A subsequent bone marrow biopsy did not show evidence of a lymphoproliferative disorder. Flow cytometry was unremarkable. Positron emission tomography (10 days after kidney biopsy) showed scattered mediastinal, pelvic, and inguinal lymph nodes up to 1 cm in diameter and a larger 3.4-cm right external iliac lymph node. Computed tomography performed 3 months later was negative for lymphadenopathy.
DISCUSSION In the case presented, the findings are consistent with cryoglobulinemic GN due to type 1 (IgG1k) cryoglobulinemia. The monoclonal cryoglobulinemia is unlikely to be directly related to HCV infection and is probably secondary to an underlying BLPD, which is supported by focal involvement of kidney parenchyma by a low-grade BLPD with plasmacytic differentiation. The diagnosis and classification of cryoglobulinemic GN is not always straightforward. The glomerular morphology can be variable from almost normal glomeruli to prominent glomerular intracapillary hypercellularity with cryoglobulin precipitates (“hyalin thrombi”).1 Crescents are rarely seen. There is not always obvious staining by immunofluorescence because the glomerular cryoglobulin deposits can be transient and focal in distribution. Table 2 lists the characteristic findings distinguishing types I, II, and III cryoglobulinemia. It is difficult to detect type III cryoglobulins in kidney biopsy specimens because the cryoglobulin is polyclonal and
Figure 1. Light microscopy findings. (A) Hypercellular glomerulus with many thickened glomerular capillary loops and occasional intracapillary hyaline thrombi (arrows). (B) Focal dense mononuclear cell infiltrate at the corticomedullary junction (hematoxylin and eosin stain; original magnifications, A, 3600; B, 3100). 704
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Glomerulonephritis With Monoclonal Deposits
Figure 2. Strong glomerular mesangial and capillary loop staining was seen for immunoglobulin G (IgG), but not for IgA or IgM. The deposits were k (K) light chain-restricted (direct immunofluorescence; original magnification, 3400). Abbreviation: L, lambda.
the deposits typically do not have a substructure. In type I cryoglobulinemia, there is deposition of monoclonal immunoglobulin, commonly IgG. In our experience, the deposits rarely have the characteristic microtubular substructure seen in type II cryoglobulinemia, but frequently have a crystalline/paracrystalline substructure with parallel arrangement of fibrils or microtubules or a fine periodicity in angularshaped crystalline-type deposits.4-6
Considering the paracrystalline substructure and monoclonal nature of the deposits in the case presented, a diagnosis of immunotactoid GN was considered. Originally, it was proposed that cases with underlying cryoglobulinemia, hematologic disorders, or systemic lupus erythematosus should be excluded as immunotactoid GNs, but cases of fibrillary GN were to be included.7 Fibrillary GN is now considered by most to be a separate entity distinct from
Figure 3. There was a focal dense mononuclear cell infiltrate in the frozen section that demonstrated staining for immunoglobulin G1 (IgG1) and k (K) light chain only (direct immunofluorescence; original magnification, 3200.) Abbreviation: L, lambda. Am J Kidney Dis. 2016;67(4):703-708
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Figure 4. Electron microscopy findings. (A) The mainly subendothelial deposits had distinct fibrillary substructure. Fibrils were localized to the deposits only; randomly arranged fibrillary material was not seen within the glomerular basement membrane or in the mesangial matrix (uranyl acetate–lead citrate; original magnification, 340,000). (B) Higher magnification of fibrils shows vaguely microtubular structure with a mean diameter of 12.2 nm (uranyl acetate–lead citrate; original magnification, 3150,000).
immunotactoid GN, and it is recognized that many cases of immunotactoid GN are associated with a BLPD or monoclonal gammopathy of undetermined significance.4-6 Despite the microtubular substructure of type II cryoglobulin deposits, cryoglobulinemic GN due to type II cryoglobulins is not considered an immunotactoid GN. In type I cryoglobulinemia, the issue is less settled because the cryoglobulinemic properties of monoclonal immunoglobulins may not always be evident clinically. It is likely that many cases diagnosed as immunotactoid GN represent monoclonal immunoglobulin deposits with cryoglobulin properties even if circulating monoclonal immunoglobulins are undetectable. Additional
glomerular diseases considered in the differential diagnosis are listed in Table 3. Laboratory testing for cryoglobulinemia can be useful; however, it can occasionally be misleading if the specimen is handled inappropriately.8 Therefore, a negative cryoglobulin test result should be interpreted with caution if there is strong clinical suspicion for cryoglobulinemia. Of note, it is useful to order both quantitative (cryoglobulin/cryocrit test) and qualitative (immunodiffusion and immunofixation) testing to sufficiently evaluate the amount of cryoglobulins, as well as to identify the cryoglobulin type. Rheumatoid factor (IgMk) is positive in type II cryoglobulinemia. Given that type I cryoglobulinemia is frequently IgG, a
Table 2. Characteristic Findings in Cryoglobulinemic GN Cryoglobulin Type I
Glomerular hypercellularity Glomerular capillary hyalin thrombi, large deposits Vasculitis in the kidney biopsy Distribution of deposits IgG in deposits IgM in deposits Substructure in deposits Rheumatoid factor Monoclonal spike in serum Low serum C3 Low serum C4 HCV infection Other infection, acute inflammation, autoimmune disease, malignancy BLPD
II
III
111 1
111 11
11 1/2
2 Diffuse, global Monoclonal (if IgG) Monoclonal (if IgM) Paracrystalline/crystalline 1/2 (if IgM) 11 1/2 1/2 2 2
1 Can be focal, segmental 111 (polyclonal) 111 (IgMk) Microtubular (20-30 nm) 111 1/2 1/2 111 111 1/2
1/2 Diffuse, global 11 to 111 (polyclonal) 11 to 111 (polyclonal) Usually none 11 2 11 11 1 11
11
2
2
Abbreviations: BLPD, B-cell lymphoproliferative disorder; HCV, hepatitis C virus; IgG, immunoglobulin G; GN, glomerulonephritis. 706
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Glomerulonephritis With Monoclonal Deposits Table 3. Morphologic Differential Diagnosis of Cryoglobulinemic GN
Cryoglobulinemic GN, type I Cryoglobulinemic GN, types II/III
Histologya
IFa
EMa
MPGN pattern with “wire loop” lesions or hyaline thrombi MPGN pattern with “wire loop” lesions or hyaline thrombi
Monoclonal IgG or IgM
Mesangial and subendothelial crystalline/paracrystalline deposits Mesangial and subendothelial electron-dense deposits; type II typically has microtubular substructure (20-30 nm) Mesangial and subendothelial electron-dense deposits with possible substructure; duplication of GBM Mesangial, subendothelial, and/or subepithelial electron-dense deposits; can have fingerprint-like substructure Microtubular or organized paracrystalline deposits in mesangium and along GBM (commonly subendothelial) Randomly arranged fibrils (10-20 nm) in mesangium and along GBM; not microtubular Mostly mesangial and subendothelial with occasional subepithelial electron-dense deposits; no substructure
IgM and IgG with both k and l light chain
MPGN associated with HCV infection
MPGN pattern without “wire loop” lesions or hyaline thrombi
Polyclonal IgG and IgM
Diffuse proliferative lupus nephritis
Endocapillary proliferation and/or “wire loop” lesions or hyaline thrombi
Polyclonal IgG; fullhouse pattern
Immunotactoid GN
Variable: MPGN pattern, mesangial expansion/ hypercellularity
Commonly monoclonal (IgG predominant)
Fibrillary GN
Variable: mesangial expansion, MPGN pattern, membranous pattern MPGN pattern . endocapillary proliferation pattern . membranous pattern
Polyclonal IgG; IgG1 and IgG4
PGNMIGD
Monoclonal IgG (mostly IgG3k)
Clinical Associations
BLPD, MGUS
Infection (HBV and HCV), autoimmune disorder
HCV infection
SLE
BLPD, MGUS, absence of type II and III cryoglobulinemias Rarely malignancy, dysproteinemia, autoimmune disorder, HCV infection23 MGUS in 30% of cases
Abbreviations: BLPD, B-cell lymphoproliferative disorder; EM, electron microscopy; GBM, glomerular basement membrane; GN, glomerulonephritis; HBV, hepatitis B virus; HCV, hepatitis C virus; IF, immunofluorescence; IgG, immunoglobulin G; MGUS, monoclonal gammopathy of undetermined significance; MPGN, membranoproliferative glomerulonephritis; PGNMIGD, proliferative glomerulonephritis with monoclonal IgG deposits; SLE, systemic lupus erythematosus. a Glomerular findings.
positive cryoglobulin test with a negative rheumatoid factor test result is suggestive of type I cryoglobulinemia. In type III cryoglobulinemia, rheumatoid factor, if present, is polyclonal. In our patient, the type I cryoglobulinemia was likely secondary to an underlying low-grade BLPD. It is well established that chronic HCV infection can be associated with atypical lymphoid proliferations, including B-cell lymphomas.9,10 Furthermore, HCV infection–associated BLPDs include monoclonal Bcell populations in peripheral blood, bone marrow, and other tissues without clinical evidence of lymphoma.10 In many cases of HCV infection–associated BLPDs, successful treatment and elimination of the HCV will result in regression of the lymphoma. The mechanism underlying the association between HCV and BLPDs appears to be a multistep and multifactorial process involving both genetic and environmental factors.11-13 Similar to gastric lymphomagenesis associated with Helicobacter pylori infections, chronic stimulation of B cells by HCV likely plays a large role. Additionally, the acquisition of multiple genetic alterations, such as Am J Kidney Dis. 2016;67(4):703-708
t(14;18) (ie, a translocation involving chromosomes 14 and 18) and BCL2 overexpression, favor B-cell survival and proliferation, promoting expansion of abnormal B-cell clones. Of note, HCV can directly infect peripheral-blood mononuclear cells, which could also be a contributing factor in the development of abnormal B-cell populations.14 In our patient, although an overt lymphoma was not detected, the monoclonal B-cell population detected in the biopsy likely represents an HCV infection–associated BLPD. It is possible that the steroid therapy the patient received as treatment for the GN was also effective in eliminating the BLPD. Although there have been recent advances in terms of targeted therapies, steroids remain a component of many frontline treatment regimens for low- and high-grade B-cell lymphomas, as well as plasma cell neoplasms.15-18 It is important to note that monoclonal B-cell populations without overt evidence of lymphoma have also been reported in the absence of HCV infection. Most commonly, monoclonal B-cell populations circulating in peripheral blood without evidence of 707
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lymphoma or meeting the criteria for chronic lymphocytic leukemia, termed monoclonal B-cell lymphocytosis, have been reported in up to 10% of adults older than 60 years using high-sensitivity flow cytometry.19 The vast majority of patients with a monoclonal B-cell lymphocytosis do not progress to clinical disease. Similar monoclonal B-cell populations without overt lymphoma can be detected in bone marrow specimens and rarely, extramedullary tissue biopsy specimens.19-21 Furthermore, indolent lymphomas can be detected incidentally in lymph node dissections performed for other reasons.19 Many incidental lymphomas are not associated with systemic dissemination, show only partial nodal involvement, and/or frequently do not require treatment, suggesting that it is possible to have only minimal/isolated involvement by an indolent lymphoma. Also, rarely, monotypic B-cell expansions can occur in reactive lymphoid proliferations.20 In summary, our case demonstrates that the correct diagnosis and typing of cryoglobulinemic GN can be difficult, even if the cryoglobulinemia appears to be associated with HCV infection. Also, our case draws attention to the possibility that, rarely, clinically undetectable “occult” BLPDs, which frequently lack a monoclonal gammopathy and bone marrow involvement, may result in significant kidney disease, similar to the occurrence of monoclonal immunoglobulin deposition disease or AL amyloidosis in patients without an overt plasma cell neoplasm. Thus, in the setting of an atypical B-cell infiltrate or in kidney diseases that can be associated with lymphoproliferative diseases, B-cell clonality studies should be a consideration. However, even in the setting of a monoclonal B-cell population, overall morphologic and clinical findings should be considered before rendering a diagnosis of lymphoma because there appear to be differences in disease behavior between occult BLPDs and typical B-cell lymphomas.22
ACKNOWLEDGEMENTS Support: None. Financial Disclosure: The authors declare that they have no relevant financial interests. Peer Review: Evaluated by an external peer reviewer, the Pathology Editor, the Education Editor, and the Editor-in-Chief.
REFERENCES 1. D’Amico G. Renal involvement in hepatitis C infection: cryoglobulinemic glomerulonephritis. Kidney Int. 1998;54: 650-671. 2. Fabrizi F, Plaisier E, Saadoun D, Martin P, Messa P, Cacoub P. Hepatitis C virus infection, mixed cryoglobulinemia, and kidney disease. Am J Kidney Dis. 2013;61:623-637. 3. Alpers CE, Smith KD. Cryoglobulinemia and renal disease. Curr Opin Nephrol Hypertens. 2008;17:243-249.
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4. Rosenstock JL, Markowitz GS, Valeri AM, Sacchi G, Appel GB, D’Agati VD. Fibrillary and immunotactoid glomerulonephritis: distinct entities with different clinical and pathologic features. Kidney Int. 2003;63:1450-1461. 5. Herrera GA, Turbat-Herrera EA. Renal diseases with organized deposits: an algorithmic approach to classification and clinicopathologic diagnosis. Arch Pathol Lab Med. 2010;134: 512-531. 6. Nasr SH, Fidler ME, Cornell LD, et al. Immunotactoid glomerulopathy: clinicopathologic and proteomic study. Nephrol Dial Transplant. 2012;27:4137-4146. 7. Schwartz MM, Korbet SM, Lewis EJ. Immunotactoid glomerulopathy. J Am Soc Nephrol. 2002;13:1390-1397. 8. Motyckova G, Murali M. Laboratory testing for cryoglobulins. Am J Hematol. 2011;86:500-502. 9. Paydas S. Hepatitis C virus and lymphoma. Crit Rev Oncol Hematol. 2015;93:246-256. 10. Mollejo M, Menarguez J, Guisado-Vasco P, et al. Hepatitis C virus-related lymphoproliferative disorders encompass a broader clinical and morphological spectrum than previously recognized: a clinicopathological study. Mod Pathol. 2014;27: 281-293. 11. Ferri C, Zignego AL, Pileri SA. Cryoglobulins. J Clin Pathol. 2002;55:4-13. 12. Ferri C, Sebastiani M, Giuggioli D, et al. Hepatitis C virus syndrome: a constellation of organ- and non-organ specific autoimmune disorders, B-cell non-Hodgkin’s lymphoma, and cancer. World J Hepatol. 2015;7:327-343. 13. Forghieri F, Luppi M, Barozzi P, et al. Pathogenetic mechanisms of hepatitis C virus-induced B-cell lymphomagenesis. Clin Dev Immunol. 2012;2012:807351. 14. Zignego AL, Macchia D, Monti M, et al. Infection of peripheral mononuclear blood cells by hepatitis C virus. J Hematol. 1992;15:382-386. 15. Lunning MA, Vose JM. Management of indolent lymphoma: where are we now and where are we going. Blood Rev. 2012;26:279-288. 16. Armitage JO. My treatment approach to patients with diffuse large B-cell lymphoma. Mayo Clinic Proc. 2012;87: 161-171. 17. Rajkumar SV. Multiple myeloma: 2012 update on diagnosis, risk-stratification, and management. Am J Hematol. 2012;87:78-88. 18. McKay LI, Cidlowski JA. Corticosteroids in the treatment of neoplasms. In: Holland-Frei Cancer Medicine. 6th ed. Hamilton, ON, Canada: BC Decker. http://www.ncbi.nlm.nih.gov/ books/NBK13383/. Accessed July 9, 2015. 19. Rawstron AC. Occult B-cell lymphoproliferative disorders. Histopathology. 2011;58:81-89. 20. Kussick SJ, Kalnoski M, Braziel RM, Wood BL. Prominent clonal B-cell populations identified by flow cytometry in histologically reactive lymphoid proliferations. Am J Clin Pathol. 2004;121:464-472. 21. Nelson BP, Abdul-Nabi A, Goolsby C, Winter J, Peterson L. Characterization of tissue findings in bone marrow biopsy specimens with small monoclonal B-cell populations. Am J Clin Pathol. 2014;141:687-696. 22. Kroft SH. Monoclones, monotypes, and neoplasia pitfalls in lymphoma diagnosis. Am J Clin Pathol. 2004;121:457-459. 23. Nasr SH, Valeri AM, Cornell LD, et al. Fibrillary glomerulonephritis: a report of 66 cases from a single institution. Clin J Am Soc Nephrol. 2011;6:775-784.
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