Renal Sarcoidosis and Multiple Myeloma

摘要

An association between sarcoidosis and multiple myeloma (MM) has been reported in several case reports. In these cases, sarcoidosis is chronically active, systemic, diagnosed at a later age than controlled groups, and often precedes the diagnosis of multiple myeloma by several years. We present the first case of a 43-year-old asymptomatic man with abnormal renal function and monoclonal gammopathy who was simultaneously diagnosed with renal sarcoidosis and MM. He was successfully treated with Thalidomide and steroids and remains in remission after two years of follow up. Pathophysiology of sarcoidosis and MM with special focus on potential link between the two diseases is discussed. Introduction Sarcoidosis is a chronic inflammatory disease with clinically significant renal involvement mostly due to hypercalcemia (10%) and hypercalciuria (50%).1 Up to 20% of sarcoidosis patients show granulomatous interstitial nephritis on biopsy and autopsy reports.2 An association between sarcoidosis and malignancy has been suggested.3 Hodgkin’s disease and non-Hodgkin lymphoma encompass the majority of cases that highlight this association.Less commonly, monoclonal gammopathies have been reported in association with sarcoidosis. There are eleven case reports of multiple myeloma (MM) in association with sarcoidosis in the literature.4 None of these cases report renal involvement. We describe a patient with simultaneous presentation of renal sarcoidosis and MM. We discuss the atypical presentation, pathophysiology and highlight the importance of performing a renal biopsy. Case Report A 43-year-old African-American male with no prior medical history was referred to outpatient nephrology clinic for evaluation of abnormal renal function found on routine health exam. Serum creatinine level was 2.4 mg/dL. Review of systems were unremarkable. He was not on any medications. His blood pressure was 138/104 mmHg. Physical examination findings were unremarkable. A complete blood count showed a white blood cell count of 4.5 x 109 L, hemoglobin 13.3 g/dL and platelet count of 135 x 109 L. Serum calcium was 9.5 mg/dL with an albumin of 3.9 g/dL and a total protein level of 9.7 g/dL. Urinalysis showed trace blood and 1+ protein with no cellular casts. He had 480 mg of proteinuria on a 24 hour urine collection. Urine calcium to creatinine ratio was within normal range (121 mg/g). Both serum and urine protein electrophoresis with immunofixation revealed monoclonal Immunoglobulin (Ig) G lambda. Quantitative serum Igs showed 43 g/L (normal range, 6-16 g/L) of IgG and normal levels of IgA and IgM. Lambda free light chains were elevated at 96.3 mg/L (normal range, 5.17-26.3 mg/L) with normal kappa free light chains of 17.8 mg/L (normal range, 3.3-19.4 mg/L). Skeletal survey radiography was negative for osteolytic bone lesions.Bone marrow biopsy and aspiration was consistent with MM without any evidence of granulomas. Percutaneous renal biopsy showed areas of non-caseating granulomatous interstitial nephritis involving approximately 50% of the cortex and medulla (Figure 1). The uninvolved areas of cortex contained 17 glomeruli and were unremarkable by light and immunofluorescent microscopy. The tubules were free of casts (Figure 2). Stains for acid fast (Fite’s) and fungal (GMS) were negative. The congo red stain in both the bone marrow and renal tissues were negative. Infectious workup including urine and sputum cultures for acid fast bacilli was negative. Serum Angiotensin Converting Enzyme (ACE) level was elevated at 81 U/L with a normal 1,25-dihydroxy Vitamin D level of 23 pg/ml. Computed Tomography scan of the chest, abdomen and pelvis revealed hilar and para-aortic abdominal lymphadenopathy consistent with the diagnosis of sarcoidosis.The patient was started on prednisone at 1mg/kg for treatment of renal sarcoidosis. He was subsequently switched to Thalidomide and Dexamethasone for treatment of multiple myeloma and remained on this therapy for 5 months. After