Our case is unique since he had mildly elevated platelet counts at baseline, which continued to raise despite the improvement of his skin condition a result of efaluzimab treatment. This is specifically interesting since efalizumab, which is a humanized anti-CD11a monoclonal antibody (IgG1) that acts by blocking the interaction of lymphocyte function-associated antigen 1 with intracellular adhesion molecule 1, was described to cause an autoimmune thrombocytopenia in 0.3% of cases based on data of the tolerance of 3291efaluzimab treated patients. There is only one other published case of a psoriasis patient that developed thrombocytosis while being treated with efalizumab. However in that case the thrombocytosis diminished gradually,upon stopping the efalizumab, and after 9 weeks,returned to normal values. The onset mechanism of this phenomenon dose not suggest an explanation.however,it is known that the activated platelets express CD11a . In our patient,the thrombocytosis was probably not an adverse reaction to efalizumab as it continued even after the drug was interrupted.