CLL/SLL with initial presentation as a longstanding cutaneous plaque: a rare case.

While chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) is the most common leukemia in the western world, it uncommonly initially presents as a cutaneous lesion. When it does, it is often found incidentally in the context of another distinct lesion. We present a case of CLL/SLL that initially presented as a solitary nodular erythematous plaque on the left flank of a healthy 60-year-old man without lymphadenopathy or constitutional symptoms. The lesion had been present for many years, but had recently begun to grow and become pruritic and painful. Excisional biopsy revealed a large nodular aggregate of variably sized CD20(dim), CD5(+), CD23(+), BCL-2(+) atypical lymphocytes in the dermis without epidermotropism. The lymphocytes were negative for BCL-1/cyclinD1, BCL-6, and CD10, and no other background lesion was identified. This constellation of biopsy findings was consistent with CLL/SLL. This case emphasizes the potential for involvement by CLL/SLL in the cutaneous biopsies of otherwise asymptomatic patients.