Rare cutaneous manifestation of B‐cell chronic lymphocytic leukaemia involving the toes

Abstract B cell chronic lymphocytic leukaemia (B‐CLL) presenting with cutaneous infiltration is rare, and when it occurs, it presents most commonly on the head and neck. We present the case of an 80‐year‐old woman with a 2‐month history of erythema, swelling and pain affecting all her toes. She had a history of B‐CLL diagnosed 20 years previously that had remained stable under observation without treatment. A toe skin biopsy showed a diffuse infiltrate of lymphoid cells occupying the dermis composed of small mature lymphoid cells with a monotonous appearance. On immunohistochemistry, the neoplastic lymphoid cells stained positive for the B‐cell marker CD20. Overall, the morphology and immunophenotype were consistent with cutaneous involvement by chronic lymphocytic leukaemia/small lymphocytic lymphoma (CLL/SLL). We concluded that her symptoms were directly caused by skin infiltration of B‐CLL.