Ln‐γ 2 chain of laminin‐332 is a useful marker in differentiating between benign and malignant sclerosing adnexal neoplasms

AIMS: Laminin (Ln)-gamma 2, one of the chains of Ln-332, is a marker of invasive tumours and is frequently expressed as a monomer in malignant tumours. Desmoplastic trichoepithelioma (DTE), some types of basal cell carcinoma (BCC) (infiltrating and morphoeic BCC) and microcystic adnexal carcinoma (MAC) belong to a group of tumours known as sclerosing adnexal neoplasms (SAN) that are frequently difficult to differentiate and often require immunohistochemistry for diagnosis. The aim of this study was to assess the usefulness of Ln-gamma 2 expression in the differential diagnosis of DTE, infiltrating/morphoeic BCC, MAC and syringoma. METHODS AND RESULTS: In this study, we compared the expression of Ln-gamma 2 in infiltrating/morphoeic BCC (n = 28), DTE (n = 26), MAC (n = 10) and syringoma (n = 20). Immunohistochemically, Ln-gamma 2 positivity was noted in 96% (27 cases) of infiltrating/morphoeic BCC and 90% (nine cases) of MAC, while all DTE and syringoma cases were negative. Furthermore, Ln-gamma 2 expression pattern in infiltrating/morphoeic BCC was different from that in MAC. Ln-gamma 2 expression was found in the cytoplasm of tumour cells in infiltrating/morphoeic BCC tumour cells, while in MAC linear expression was noted both along tumour nests and in the cytoplasm. CONCLUSION: Ln-gamma 2 is a helpful adjunct in the differential diagnosis of SAN.