A condition closely mimicking IgG4-related disease despite the absence of serum IgG4 elevation and IgG4-positive plasma cell infiltration

Figures & data

Figure 1. Diagnostic imaging shows multiple organ involvement. (a) Positive emission tomography shows accumulation of fluorodeoxyglucose in the parotid and submandibular glands, lymph nodes, lungs, pancreas, kidneys, and prostate. (b)–(c) Enhanced CT showed submandibular, supraclavicular, axillary, mediastinal, paraaortic, and inguinal lymph node swelling, interstitial pneumonia with small nodular lesions and bronchiectasis in the lung, patchy hypoattenuated lesions in the pancreas head and body, multiple low-density lesions in the kidney, and abdominal aortic aneurysm with aortic wall thickening.

Figure 2. (a)–(e) Renal biopsy, (f)–(g) Inguinal lymph node biopsy. (a) Renal biopsy reveals lymphoplasmacytic infiltration with fibrosis mimicking IgG4-related tubulointerstitial nephritis. A regional lesion distribution is evident. The glomeruli and vessels show only minor abnormalities (PAS, × 100). (b) Dense infiltration of plasma cells and lymphocytes is seen. A few eosinophils are also seen (HE, × 400). (c) Lymphocytes and plasma cells are surrounded by storiform fibrosis, the so-called bird's eye pattern (PAM, × 400). (d) Infiltration of many plasma cells is seen (CD138, × 100). (e) IgG4-positive plasma cells are infrequent (IgG4, × 100). (f) Decreasing lymph follicle, atrophic follicle, expansion of interfollicular region and dense plasma cell and lymphocyte infiltration with a few eosinophils (HE, × 100). (g) IgG4-positive plasma cells are infrequent (IgG4, × 100).

Figure 3. Immunostainings of IgG subclasses. (a)–(d) Inguinal lymph node biopsy, (e)–(h) Small salivary gland biopsy. (a) IgG1 (× 200), (b) IgG2 (× 200), (c) IgG3 (× 200), (d) IgG4 (× 200), (e) IgG1 (× 400), (f) IgG2 (× 400), (g) IgG3 (× 400), (h) IgG4 (× 400). Note that IgG4-positive plasma cells are scant both in inguinal lymph node and small salivary gland.

Figure 4. Enhanced CT after steroid administration shows improvement of multiple low-density lesions in the kidney.

Figure 5. Double immunostaining of CD4 and CD25 in tubulointerstitial lesion. Mononuclear cells positive for CD4 (red) or CD25 (green) are detected. The merge image showed a few cells doubly positive for CD4 and CD25 in an area of interstitial cell infiltration lesion (arrows).