IgG4-related kidney disease presenting as a cystic renal mass: a case report and literature review / 中华泌尿外科杂志

ABSTRACT

Objective:To investigate the clinical characteristics, differential diagnosis and treatment of IgG4-related kidney disease (IgG4-RKD) presenting as a cystic renal mass.Methods:A 42-year-old male patient was found having a tumor in the left kidney in an annual physical examination. Subsequent CTU scan revealed a round shadow in the lower pole of the left kidney, with slightly lower, uneven density and obscure boundaries, which was slightly enhanced on contrast-enhanced CT imaging, suggesting a cystic mass (Bosniak category Ⅲ). Contrast-enhanced MRI showed a long T1, long T2 signal lesion in the lower pole of the left kidney, which was not obviously enhanced in the cortical phase but exhibited continuous and separated enhancement in parenchymal and delayed phases, suggesting a cystic renal cell carcinoma. A preoperative diagnosis of a left renal mass was made, for which the patient underwent a laparoscopic partial nephrectomy.Results:The resected cystic mass was grey white with obscured boundaries. Microscopically, the mass showed lymphoplasmacytic hyperplasia with lymphoid follicles, cystic formation, fibrosis hyperplasia and vascular obstruction. Immunohistochemistry revealed that the number of IgG4 (+ ) plasma cells was more than 50/HPF, and over 40% IgG (+ ) plasma cells were IgG4 (+ ). By virtue of the radiologic and pathologic findings, the patient was diagnosed with IgG4-RKD. At 2 weeks after operation, serum IgG level was 0.71g/L (reference 0.03-2.01 g/L). Chest and abdominal CT scans performed 3 months after operation showed no evidence of other organ involvement and serum IgG4 level was within the normal range. Therefore no adjuvant therapy was prescribed.Conclusions:It is usually difficult to differentiate IgG4-RKD presenting as a cystic renal mass by radiography alone. The presence of other organ involvement, serum IgG4 test and renal biopsy can help the diagnosis and so as to avoid unnecessary surgery.