PMC10291080_01
Hematoxylin and eosin stained (H&E) sections of the clear renal cell carcinoma with metastatic infiltrating lobular breast carcinoma. Clusters of breast cancer cells are embedded within ccRCC [(A): bar = 400 mum; (B): bar = 200 mum].
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F1
The neoplastic cells of the first lesion demonstrated typical clear cell renal cell carcinoma (ccRCC) pattern, showing clear cytoplasm with round nuclei and inconspicuous nucleoli (WHO/ISUP grade 1) (Figure 1). Metastatic invasive lobular carcinoma of the breast was observed within the ccRCC (Figure 1), forming nests or clusters of small cells, which exhibited diffuse growth pattern that invaded a "pool" of clear cells.
Immunohistochemical staining of panel for ccRCC and panel for lobular breast carcinoma. (A-C) representative ccRCC markers: CA IX, CD10, and PAX8; (D-F) representative lobular breast carcinoma markers: ER, HER2 and E-cadherin. Bar = 400 mum.
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F2
Immunohistochemical stains confirmed this neoplasm as ccRCC: it was positive for CA IX, CD10, PAX8, PAX2, and Vimentin; negative for CD117, CK7 and breast carcinoma markers (Figure 2). Several breast lobular carcinoma markers were positive: ER (80%+), HER2 (1+) (Figure 2), and GCDFP15(1+) (Figure 3) while renal cell carcinoma markers were negative, indicating the exclusion of ccRCC.
Immunohistochemical staining of GCDFP15 (B) with corresponding H&E section (A), confirming lesions originated of breast. Bar = 400 mum.
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F3
Several breast lobular carcinoma markers were positive: ER (80%+), HER2 (1+) (Figure 2), and GCDFP15(1+) (Figure 3) while renal cell carcinoma markers were negative, indicating the exclusion of ccRCC.