Monoclonal Gammopathy of Renal Significance with Progression to Multiple Myeloma in a Patient with ASIA-MO Syndrome

Figure 2

Renal biopsy immunohistochemistry. (a) In the microphotograph with HyE, we can observe part of the medulla composed by tubules with acute tubular necrosis and disappearance of nuclei in a few cells. The interstitium is altered by the presence of the chronic lymphoplasmacytic infiltrate, arranged by cumulus in some areas, but also the presence of slight fibrosis. (b) Masson staining shows interstitial thickening secondary to the lymphoplasmacytic infiltrate reaching the proximal contoured tubules giving an irregularity in its contour. As a paramount feature, the presence of eosinophilic inclusions (arrowhead) in the cytoplasm of the epithelium covering these tubules is seen and also the desquamation of this epithelium which is compatible with LCPT (arrow). Blue staining confirms the presence of slight fibrosis. (c) Immunohistochemical staining for CD138 (plasma cell biomarker) was performed with a significant reaction at the membrane level highlighting the abundant presence of plasma cells. (d) Reaction to kappa light chains (brown staining) shows variable positivity inside the cytoplasm of plasma cells at the interstitium, which represents its monoclonality.

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