BACKGROUND: Hematologic malignancies expressing CD4 and CD56 are most commonly associated with the recently described CD4(+) CD56(+) hematodermic neoplasm. METHODS: Thirteen cases of CD4(+) CD56(+) hematologic malignancies were prospectively encountered in the routine and referral practices of the authors. RESULTS: Patients 1 and 2 were elderly men exhibiting an acute onset of skin, bone-marrow, and peripheral blood involvement, both dying of their disease within less than 12 months. CD3(+) phenotype and a clonal T-cell receptor beta rearrangement indicated categorization as a CD4(+) natural killer T-cell lymphoma. Patient 3 developed a CD56(+) anaplastic large cell lymphoma and is without disease after excision and radiation. Indolent CD4(+) CD56(+) poikilodermatous mycosis fungoides defined case 4. There were 7 patients with CD123(+) CD4(+) CD56(+) hematodermic neoplasm, 4 dying within 18 months of presentation with peripheral blood/marrow involvement in 6 of the 7 cases. Two patients with granulocytic sarcoma dying within 100 days of presentation defined the last two cases. LIMITATIONS: There were relatively small numbers in each of the categories and the follow-up was limited in those cases where death was not reported. CONCLUSION: Cutaneous malignancies composed of CD4(+) CD56(+) hematopoietic cells define a varied group and oftentimes have an aggressive clinical course although not in every case.
