Diagnostic approach to leukemia cutis : A differential diagnostic step-by-step algorithm.

Objectives: Leukemia cutis is a conflicting term to describe neoplastic hematopoietic infiltrates in the skin. Cutaneous myeloid or lymphoid proliferations often present a serious differential diagnostic challenge for pathologists.

Methods: This review aims to outline the confusion associated with the term leukemia cutis and discuss in detail the foremost common differential diagnoses in daily practice. The review is based on a summary of the relevant literature as well as on the authors' experience.

Results: It addresses precursor cell myeloid and lymphoid tumors that are strictly considered true leukemia cutis but also more mature neoplasms, including some recently described mature extramedullary myeloid proliferations. Finally, a practical, comprehensive stepwise approach combining traditional immunohistochemical marker panels, novel lineage- or mutational-specific markers, and other ancillary tests is suggested to reach an entity-specific diagnosis.

Conclusion: The proper combination of ancillary techniques can help the pathologist to provide an accurate diagnosis of these challenging skin lesions.