Bone involvement in two cases of thoracic primary cutaneous diffuse large B-cell lymphoma, leg type.

Primary cutaneous diffuse large B-cell lymphoma, leg type (PCLBCL-LT), is defined by a predominance of confluent sheets of centroblasts and immunoblasts, which strongly express Bcl-2 protein. This cutaneous lymphoma is mainly characterized by the development of skin lesions on the lower leg. Other localizations are possible (namely non-leg PCLBCL-LT) and usually affect younger patients. PCLBCL-LT is distinguished from the two other subtypes of primary cutaneous B-cell lymphomas by its immunohistopathological features, its aggressive clinical behaviour with a worse prognosis linked to skin recurrences, but also secondary extracutaneous spread. Bone involvement underlying skin lesions has been reported in few series and cases reports during PCLBCL-LT. We describe here two aggressive cases of PCLBCL-LT with high burden and infiltrative thoracic tumours, with localized bone involvement.