Test Details: Immunohistochemical testing is carried out on biopsy/resected tissue specimen. This testing helps to identify specific antigens (proteins) within tissue sections utilizing an antigen-specific antibody .Cyclin D1 (also known as bcl-1) is a cell cycle protein involved in the regulation of cyclin-dependent kinases of the first gap phase (G1) of the cell cycle. Cyclin D1 overexpression—caused by the t(11;14) translocation associated with mantle cell lymphoma—makes it a characteristic marker. It is also expressed in Inflammatory pseudotumor (myofibroblastic tumour), hairy cell leukaemia, multiple myeloma.