#00065770

Figure 1. Bone marrow biopsy involved by metastatic prostate adenocarcinoma and plasma cell neoplasm.
1A. H&E stain showing infiltrating malignant glands (black circles), consistent with metastatic adenocarcinoma, and sheets of atypical plasma cells (black arrows) replacing the marrow space (original magnification ×200).
1B. Immunohistochemical stain for PSA demonstrating diffuse cytoplasmic positivity in tumor cells (original magnification ×200). 1C. CD138 immunostain highlighting diffuse plasma cell infiltrate (original magnification ×200). 1D. Lambda immunostain demonstrating diffuse light chain restriction in the neoplastic plasma cells (original magnification ×200).

 

Bone marrow biopsy shows near-total replacement of normal hematopoietic tissue by infiltrating malignant glands, consistent with metastatic adenocarcinoma, and demonstrates marked involvement by a plasma cell neoplasm. On H&E (Figure 1A), the tumor is arranged in irregular nests and glands composed of cells with enlarged nuclei, prominent nucleoli, and moderate eosinophilic cytoplasm (black circles). Immunohistochemical staining for PSA (Figure 1B) shows strong, diffuse cytoplasmic positivity, supporting prostatic origin.

Sheets of atypical plasma cells (black arrows, Figure 1A) also replace much of the normal hematopoietic marrow. The neoplastic plasma cells are medium to large, with eccentric nuclei, clumped (“clock-face”) chromatin, and abundant basophilic cytoplasm. Immunohistochemical staining demonstrates strong CD138 positivity (Figure 1C) and lambda light chain restriction (Figure 1D), confirming clonality.