B-Cell Acute Lymphoblastic Leukemia Presenting as Leukemia Cutis: A Case Report.

Leukemia cutis (LC) is a manifestation of leukemia with infiltration of the dermis, epidermis, or subcutis by malignant leukocytes resulting in papules, plaques, nodules, or ulcers. It is usually associated with acute and chronic myeloid leukemia as well as T-cell acute lymphoblastic leukemia (T-ALL) but is very rare in patients with B-cell acute lymphoblastic leukemia (B-ALL). We report a case of a 58-year-old Hispanic male who presented with a non-healing leg ulcer of three months along with patches on the face, left arm, and bilateral legs with white blood cell (WBC) count of 50800/mm with 83% blasts, and flow cytometry findings of B-ALL. Punch biopsies from affected skin showed numerous dermal nodules composed of large atypical cells with open chromatin and prominent nucleoli. Immunohistochemical stains were consistent with B-ALL involving the skin and a diagnosis of LC was rendered. A high index of suspicion in relevant cases and prompt diagnosis is imperative to prevent any delays in appropriate therapy. Diagnosis in our case was aided by concurrent identification of B-ALL in the patient's peripheral blood. Since this information may not always be available, it is important to keep B-ALL in the differential any time there is a neoplastic infiltration of leukocytes in the dermis.