Plasma Cell / Multiple Marker : CD 138

Positive CD138 means the tissue expresses syndecan‑1, a marker of plasma cells. It supports plasma‑cell differentiation and helps diagnose plasma‑cell neoplasms (for example, multiple myeloma or plasmacytoma) or reactive plasma‑cell infiltrates. Some epithelial tumors can also show CD138, so interpretation requires correlation with morphology and additional markers. It is detected by immunohistochemistry and typically stains membrane and cytoplasm.

CD138 positive in plasma cells means the cells express the surface proteoglycan CD138 (syndecan‑1), identifying them as differentiated plasma cells. Pathologists use CD138 immunostaining or flow cytometry to detect and quantify normal or abnormal plasma cells and to help diagnose plasma‑cell disorders (e.g., multiple myeloma), often alongside light‑chain restriction and other markers. CD138 also mediates cell adhesion.

CD138 is an immunostain for plasma cells. Positive CD138 highlights plasma cell numbers in marrow or tissue; increased CD138+ cells indicate plasma‑cell proliferation. Interpret percentage and clonality: small, scattered CD138+ cells may be reactive; a clonal expansion (assessed by kappa/lambda or flow) with ≥10% marrow plasma cells suggests a plasma‑cell disorder, while ≥60% clonal cells is myeloma‑defining. Correlate with morphology, labs, and imaging.

CD138 positivity usually indicates a plasma‑cell malignancy (e.g., multiple myeloma). Management begins with confirmation (bone‑marrow biopsy, imaging, cytogenetics) and risk stratification. Treatment commonly uses combination systemic therapy (proteasome inhibitors, IMiDs, corticosteroids ± monoclonal antibodies), autologous stem‑cell transplant for eligible patients, and supportive measures (bisphosphonates, infection and thrombosis prophylaxis). Close monitoring and individualized plans are essential.

Multiple myeloma is a cancerous disorder in which abnormal plasma cells proliferate in the bone marrow, producing a monoclonal immunoglobulin (M protein). It causes bone pain and lytic lesions, anemia, high calcium, kidney dysfunction and increased infection risk. Diagnosis uses blood and urine protein tests, bone marrow biopsy and imaging. Treatment includes chemotherapy, targeted agents, immunotherapy and stem cell transplant.

A CD138 biopsy refers to using CD138 (syndecan‑1) immunohistochemical staining on a tissue or bone‑marrow biopsy to identify and quantify plasma cells. It highlights plasma‑cell membranes, helping diagnose and monitor plasma‑cell disorders such as multiple myeloma and assess marrow infiltration or clonal populations (often with kappa/lambda staining). The biopsy itself carries standard sampling risks.