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Abstract: TH-PO558

Lysozyme-Induced Nephropathy as a Cause of Interstitial Nephritis in Sarcoidosis

Session Information

  • Trainee Case Reports - I
    October 25, 2018 | Location: Exhibit Hall, San Diego Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: Trainee Case Reports

  • 1502 Pathology and Lab Medicine: Clinical

Authors

  • Yoda, Shohei, Japan Community Health Care Organization Sendai Hospital, Sendai, Japan
  • Sanada, Satoru, Japan Community Health Care Organization Sendai Hospital, Sendai, Japan
  • Sato, Mitsuhiro, Sendai Shakaihoken Hospital, Sendai, Japan
  • Sato, Toshinobu, Japan Community Health Care Organization Sendai Hospital, Sendai, Japan
  • Taguma, Yoshio, Japan Community Health Care Organization Sendai Hospital, Sendai, Japan
Introduction

Sarcoidosis manifests interstitial nephritis of an unknown etiology. We report a case series of interstitial nephritis in patients with sarcoidosis, that could be associated with lysozyme-induced tubular injury.

Case Description

Kidney biopsy specimens of four cases of sarcoidosis, four cases of other interstitial nephritis such as drug-induced, IgG4-related and Sjogren syndrome, and one case of chronic myelomonocytic leukemia induced interstitial nephritis were analyzed retrospectively by immunohistochemistry and electron microscopy.
All four patients with sarcoidosis showed interstitial nephritis in the kidney. Specimens were stained with anti-lysozyme antibody and showed positive staining in proximal tubular cells, whereas negative immunostainings in the other three cases of interstitial nephritis. Strong lysozyme staining was also present in interstitial nephritis caused by chronic myelomonocytic leukemia, the mechanism of which is known as a lysozyme-induced tubular injury. The serum lysozyme level increased slightly in sarcoidosis and was markedly elevated in chronic myelomonocytic leukemia. Electron microscopy revealed increased number and size of lysosomes in proximal tubules of sarcoidosis and chronic myelomonocytic leukemia, those of which were associated with serum lysozyme levels.

Discussion

Underlying mechanisms of interstitial nephritis in sarcoidosis could be associated with proximal tubular absorption of lysozyme. We suggest that tubular injury of both sarcoidosis and chronic myelomonocytic leukemia could be categorized into lysosome-induced nephropathy. Chronic myelomonocytic leukemia induces acute kidney injury with overloaded lysozyme to the proximal tubules. On the other hand, chronic tubular injury of sarcoidosis may be associated with above average lysozyme stress on the tubules.