Differentiation and clonality of lesional lymphocytes in pityriasis lichenoides chronica.

BACKGROUND: Pityriasis lichenoides chronica (PLC) and pityriasis lichenoides et varioliformis acuta (PLEVA) are benign T-cell diseases that share several overlapping clinicopathologic features, leading many to believe that they exist as a spectrum rather than as single entities. Previous molecular studies have shown that PLEVA is a clonal lymphoproliferative disorder. To further characterize the immunohistologic features of PLC and to determine whether PLC demonstrates clonality, we studied 6 cases of PLC using a frozen section-immunoperoxidase technique and polymerase chain reaction/denaturing gradient gel electrophoresis. OBSERVATIONS: All 6 cases showed a mild to moderate superficial and deep perivascular infiltrate composed predominantly of CD4(+) T cells, admixed with Langerhans cells and macrophages; most were associated with an HLA-DR(+) epidermis. Three of 6 cases involved monoclonal T-cell receptor gamma (TCR gamma) gene rearrangements detected by V gamma 1-8/J gamma 1-2 and V gamma 9/J gamma 1-2 primers. CONCLUSIONS: Our findings enhance existing data showing that PLC shares many immunohistologic features with PLEVA and indicating that PLC is frequently a clonal T-cell disease. This provides further evidence that PLC and PLEVA are interrelated processes within the larger group of T-cell lymphoproliferative disorders.

Solitary primary cutaneous CD30+ large cell lymphoma of natural killer cell phenotype bearing the t(2;5)(p23;q35) translocation and presenting in a child.

Primary cutaneous CD30+ large cell lymphoma is an unusual tumor most commonly seen in adults. Most of these lymphomas are of T-cell origin and carry a good prognosis. We present the case of a 4-year-old girl with stage IEA CD30+ large cell lymphoma with a CD56+ natural killer cell phenotype and the t(2;5)(p23;q35) translocation. After excision, the patient has been free of disease for 44 months. Primary cutaneous CD30+ large cell lymphoma is uncommon in children. To our knowledge, primary cutaneous CD30+ natural killer type lymphoma has not been reported previously. The indolent behavior of this tumor indicates its similarity to other primary cutaneous CD30+ large cell lymphomas and its difference from other CD56+ lymphomas involving the skin, which often exhibit an aggressive clinical course. Cases such as this one illustrate why the use of a single, or even a few, immunohistochemical stains can be misleading in regard to lymphoma classification and prognostication.