Atypical Cutaneous Manifestation Leading to the Diagnosis of Chronic Lymphocytic Leukemia.

We report a 64-year-old male with rheumatoid arthritis and Raynaud's phenomenon who presented with diffuse arthralgias and progressive ulcerating lesions involving the palms and elbows. Differential diagnoses included recurrent Rickettsial infection, vasculitis, pyoderma gangrenosum, and cutaneous tuberculosis. Laboratory studies demonstrated marked leukocytosis (135.4 ×10⁹/L), while computed tomography (CT) imaging revealed hepatomegaly, lymphadenopathy, and pulmonary micronodules concerning for infiltrative disease. Additional history revealed a 40-pound unintentional weight loss over three months. Peripheral flow cytometry established a new diagnosis of chronic lymphocytic leukemia (CLL), and skin punch biopsy demonstrated epidermal necrosis with dense dermal lymphoid infiltrates consistent with leukemia cutis. This case highlights leukemia cutis as a rare initial manifestation of CLL that may mimic infectious or autoimmune conditions, emphasizing the importance of thorough evaluation of unexplained cutaneous lesions and significant leukocytosis to facilitate earlier diagnosis and treatment consideration.