CAM5.2

CAM5.2 is a monoclonal antibody used by pathologists to detect low-molecular-weight cytokeratins (cytokeratins 8 and 7) in tissue samples. Because mesothelioma cells almost always express these cytokeratins, a positive CAM5.2 stain helps confirm that a tumor is of mesothelial or epithelial origin rather than a lymphoma, melanoma, or sarcoma. It is one of several stains used in the workup of suspected mesothelioma.

Origin

CAM5.2 was developed in the early 1980s by Becton Dickinson as a mouse monoclonal antibody raised against cytokeratins from a human colon carcinoma cell line. The "CAM" designation reflects the manufacturer's internal clone naming rather than "cell adhesion molecule," and 5.2 identifies the specific hybridoma clone.

Significance in Asbestos Context

For a patient being evaluated for mesothelioma, CAM5.2 is one of the immunohistochemistry (IHC) stains a pathologist uses on a biopsy to distinguish mesothelioma from other cancers that can appear in the pleura, peritoneum, or lung, particularly metastatic carcinomas, lymphomas, and sarcomas. Strong positive staining supports a mesothelial or carcinoma origin and essentially rules out tumors like lymphoma or melanoma. The result is usually reported in the pathology report alongside other markers (such as calretinin, WT-1, D2-40, BAP1, and pan-cytokeratin AE1/AE3). A definitive mesothelioma diagnosis supported by a thorough IHC panel, including CAM5.2, is often the foundation of both treatment planning and any later legal claim, because trusts and courts typically require pathology-confirmed diagnosis.

Example Sentence

The biopsy report noted that the tumor cells stained strongly positive for CAM5.2 and calretinin, supporting the diagnosis of epithelioid mesothelioma.

Related Terms

Immunohistochemistry, Cytokeratin, Calretinin, Epithelioid Mesothelioma, BAP1, Pan-Cytokeratin AE1/AE3

Notes

• Request a full copy of the pathology report, including the immunohistochemistry panel results. CAM5.2 should appear alongside other mesothelial and carcinoma markers, not in isolation.
• If CAM5.2 is the only cytokeratin stain performed, ask whether additional markers (calretinin, WT-1, D2-40, BAP1, MTAP, claudin-4) were used to confirm mesothelioma and exclude metastatic carcinoma; current diagnostic guidelines call for a panel approach.
• Preserve the original tissue blocks and slides. They may be needed for second-opinion review at a mesothelioma specialty center (such as a National Cancer Institute–designated center) and for any future legal claim.
• A CAM5.2-positive result alone does not confirm mesothelioma; sarcomatoid mesotheliomas in particular can stain weakly, so ask whether pan-cytokeratin AE1/AE3 was also performed if the diagnosis is uncertain.