Focal and segmental glomerulosclerosis and plasma cell proliferative disorders

Background: Focal and segmental glomerulosclerosis (FSGS) is a common histological finding in patients with proteinuria. The natural history of the condition varies, and although it may be responsive to therapy, FSGS is an important cause of end-stage renal disease. FSGS can be caused by a variety of conditions, but it has been reported rarely in association with a plasma cell disorder. Methods: Mayo Clinic databases were queried and cross-referenced for FSGS and plasma cell disorders. The diagnoses were confirmed, and relevant clinical and laboratory data were abstracted. Results: A cohort of 13 patients with "Idiopathic" FSGS and a monoclonal plasma cell disorder were identified. Four patients had myeloma, and 9 patients had monoclonal gammopathy of undetermined significance. Patients treated for myeloma experienced improvement in their renal lesion, and the latter relapsed when the myeloma relapsed. Conclusion: We show that FSGS and plasma cell disorders are temporally and epidemiologically linked. Therapy for the underlying plasma cell disorder can lead to resolution of FSGS. The emerging molecular pathogenesis of both FSGS and myeloma also provides potential mechanisms that link the 2 conditions together. Thus, physicians must rule out a plasma cell proliferative disorder in patients with FSGS before concluding that the renal lesion is idiopathic. Moreover, FSGS may respond favorably after the underlying plasma cell disorder is controlled.