Kidney Week

Abstract: TH-PO538

THSD7A Associated Membranous Glomerulonephritis Due to Antibody Produced by Lymph Node around Metastasis of the Thymoma

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

• 1202 Glomerular Diseases: Immunology and Inflammation

Authors

• Han, Wei, St.Marianna university school of medicine, Kawasaki,, Kanagawa prefecture, Japan

Wei Han,

• Suzuki, Tomo, St.Marianna university school of medicine, Kawasaki,, Kanagawa prefecture, Japan

Tomo Suzuki,

• Watanabe, Shiika, St.Marianna university school of medicine, Kawasaki,, Kanagawa prefecture, Japan

Shiika Watanabe,

• Nakata, Mayumi, St.Marianna university school of medicine, Kawasaki,, Kanagawa prefecture, Japan

Mayumi Nakata,

• Ichikawa, Daisuke, St.Marianna university school of medicine, Kawasaki,, Kanagawa prefecture, Japan

Daisuke Ichikawa,

• Ikemori, Atsuko, St. Marianna University School, Kawasaki, Kanagawa, Japan

Atsuko Ikemori,

• Koike, Junki, St.Marianna University, Kawasaki, Kanagawa, Japan

Junki Koike,

• Shibagaki, Yugo, St.Marianna university school of medicine, Kawasaki,, Kanagawa prefecture, Japan

Yugo Shibagaki,

Introduction

Membranous glomerulonephritis (MGN) are known to be associated with malignant tumor and tumor resection can lead to remission of MGN. MGN with thrombospondin type-1 domain-containing 7A (THSD7A), which is one of the transmembrane protein antigen to podocyte, have been recently reported to be also associated to malignancy. We present a first case of THSD7A-associated MGN with thymoma that was later diagnosed with lymphatic metastasis.

Case Description

A 61-year-old woman with past medical history of asthma was referred to our clinic for bilateral edema in lower extremities and proteinuria. Her labs showed nephrotic syndrome and kidney biopsy was done. Although there was no proliferative nor spike lesions in glomeruli on light microscopy, IgG and THSD7A were stained strongly positive along glomerular capillary on immunofluorescence and subepithelial deposits on electron microscopy. Thus, she was diagnosed as THSD7A-associated MGN and subsequently found to have thymoma. She underwent extended thymectomy and postoperative radiation since thymoma type B3 was confirmed pathologically. However, proteinuria persisted in spite of steroid administration for asthma. Three years later, positron emission tomography (PET) revealed a tumor of right subclavian space, in which biopsy specimen showed histology similar to that of thymoma, thus diagnosis of metastatic recurrence was made. She underwent another course of radiation, followed by a PET confirming the complete disappearance of the metastasis, and proteinuria decreasedto less than 1 g/gCr in a year. Additional investigation revealed that, although anti-THSD7A antibody was negative in thymoma itself and in metastatic lesion, it stained strongly positive in the cells of the lymphatic node around the metastatic lesion just as staining in the glomeruli.

Discussion

We report a first case as far as we know showing the THSD7A-associated MGN with metastatic thymoma. It is intriguing that thymectomy itself could not result in remission of her proteinuria presumably due to continued exposure to THSD7A antibody produced by the lymph node around the metastasis. We need to keep in mind of searching for metastasis or remnant tumor in cases which proteinuria does not respond well to tumor resection in THSD7A associated MGN complicated in malignancy.