Tubulointerstitial nephritis in a patient with eosinophilic fasciitis and IgA nephropathy

We report a tubulointerstitial nephritis in a patient with eosinophilic fasciitis and IgA nephropathy. Urinalysis revealed mild proteinuria and microscopic hematuria, and renal biopsy disclosed diffuse interstitial infiltrations of lymphocytes and plasma cells with few eosinophils in spite of mild mesangial proliferation with IgA deposits, indistinguishable from those of primary tubulointerstitial nephritis. Immunohistochemical examination showed a predominance of helper/inducer T cells infiltrating the renal interstitium and the fascia. Corticosteroid treatment led to a decrease of infiltrating cells in both tissues. Therefore, eosinophilic fasciitis and tubulointerstitial nephritis in our patient seemed to be interdependent phenomena.