Challenge in diagnosis of CD56+ lymphoproliferative disorders: two cases of CD56+CD33+ lymphoma/leukemia.

Two cases of CD56+CD33+ leukemia/lymphoma are reported. The patient in case 1 presented with skin rash, diffuse lymphadenopathy, and hepatosplenomegaly. Blasts with monocytoid and lymphoid features were present in the peripheral blood. The tumor cells expressed HLA-DR, CD4, CD33, CD38, and CD56. Cytogenetic analysis revealed del(2)(p13),del(9)(q22),add(6)(q25),add(12)(p12),-13,-18, and -20. The clinicopathologic features were similar to those of blastic natural killer cell leukemia/lymphoma or type 2 dentritic cell leukemia. The patient in case 2 presented with generalized weakness and skin erythema not responding to antibiotics. Circulating blasts with monocytoid features were seen in the peripheral blood. The tumor cells expressed CD7, CD13, CD33, CD38, and CD56, and cytogenetic analysis revealed -5,add(7)(p22),-8, del(10)(p11.2),-12,der(13; 14)(p10;p10),+14,-16,-18,-19, and del(20)(q13.1). The clinicopathologic features were consistent with a myeloid/ natural killer cell precursor acute leukemia. Both disorders are aggressive hematopoietic malignancies that have similar clinical presentation and morphology but differ in immunophenotype and cytogenetic features.