PAX8 Distinguishes Diffuse Large B-Cell Lymphoma Mimicking Sarcoma

Figure 2

Morphologic and immunohistochemical features of the renal neoplasm support a diagnosis of diffuse large B-cell lymphoma. (a) H&E staining demonstrates an epithelioid neoplasm with a distinctive infiltrative pattern between renal tubules (nonneoplastic renal tubules highlighted by arrows). (b) An EMA immunostain is immunoreactive in the nonneoplastic renal tubules, but negative in the neoplasm. (c) A PAX8 immunostain is diffusely and strongly positive in both nonneoplastic renal tubules (red ovals) and the infiltrative neoplasm. (d–f) Subsequent LCA, PAX5/BSAP, and CD5 immunostains support the diagnosis of diffuse large B-cell lymphoma. Note the absence of PAX5 in nonneoplastic renal tubules (red ovals) and the presence of CD5 in nonneoplastic T-cell lymphocytes.

(a) H&E

(b) EMA

(c) PAX8

(d) LCA

(e) BSAP

(f) CD5