primary cutaneous large B-cell lymphoma

In the World Health Organization (WHO) 2008 classification 2 main types of primary cutaneous large B-cell lymphomas (PCLBCLs) are distinguished: primary cutaneous follicle center lymphoma (PCFCL) and primary cutaneous large B-cell lymphoma, leg type (PCBCL-LT).

PCFCL has a 5-year overall survival rate of 95%, and PCBCL-LT of approximately 50%.

Expression profiling studies have shown higher RNA expression of the IgM heavy chain in PCBCL-LT compared with PCFCL.

Hence, staining for IgM on paraffin-embedded sections seems to be an additional tool for differentiating between the 2 entities in clinical pathology practice.

Analogous to other nodal and extranodal large B-cell lymphomas, expression of IgM in PCLBCL seems to be related to an activated B cell-like phenotype. (20551823)

Finally, the expression of IgM (and IgD) in this type of lymphoma might imply defective class switch recombination. (20551823)

References

 IgM expression on paraffin sections distinguishes primary cutaneous large B-cell lymphoma, leg type from primary cutaneous follicle center lymphoma. Koens L, Vermeer MH, Willemze R, Jansen PM. Am J Surg Pathol. 2010 Jul;34(7):1043-8. PMID: 20551823

 Genetic Aberrations in Primary Cutaneous Large B-Cell Lymphoma: A Fluorescence In Situ Hybridization Study of 25 Cases. Wiesner T, Streubel B, Huber D, Kerl H, Chott A, Cerroni L. Am J Surg Pathol. 2005 May;29(5):666-673. PMID: 15832092