Atopic Dermatitis-Like Non-Erythrodermic Leukemic Variant of CD3−/+dimCD4+Cutaneous T-Cell Lymphoma Preceded by Cutaneous Papular Xanthomatosis

Peripheral blood findings in erythrodermic patients: importance for the differential diagnosis of Sézary syndrome

Although Sézary syndrome (SS) represents an advanced stage of cutaneous T-cell lymphoma, this diagnosis presents a challenge even for the most experienced dermatologic clinicians. SS is characterized clinically by erythroderma, but can also be identified in the presence of specific histologic and peripheral blood findings. Erythrodermic cutaneous T-cell lymphoma can mimic a number of nonmalignant disorders with erythroderma, including pityriasis rubra pilaris, psoriasis, atopic dermatitis, and graft-versus-host disease. The diagnosis is made even more challenging because the histology of SS is often nonspecific and rarely pathognomonic. As a result, peripheral blood studies in patients with erythroderma are frequently informative in the diagnosis of SS. Peripheral blood abnormalities including elevated CD4/CD8 ratio, aberrant CD26, CD27 and CD7 expression, and T-cell clonality can all be used to help arrive at a diagnosis. This review evaluates current data on the usefulness and limitations of specific peripheral blood markers detected by flow cytometry and T-cell receptor gene rearrangement polymerase chain reaction.

Usefulness of flow cytometry in the diagnosis of mycosis fungoides

BACKGROUND

The pathologic evaluation of mycosis fungoides (MF) is a challenging area in dermatopathology.

OBJECTIVE

We sought to determine the usefulness of flow cytometry for the diagnosis of MF from skin biopsy specimens.

METHODS

Skin biopsy specimens from 22 patients with a clinical suggestion for MF were evaluated by 4-color flow cytometry. The results were correlated with the International Society for Cutaneous Lymphoma (ISCL) MF diagnostic score and molecular studies for T-cell receptor gene rearrangement.

RESULTS

A T-cell abnormality by flow cytometry was identified in all 11 patients with diagnostic ISCL scores whereas the 7 patients with either subdiagnostic ISCL scores or reactive histology showed no phenotypic abnormality by flow cytometry. In all, 10 of 11 patients with diagnostic skin biopsy specimens for MF had T-cell receptor gene rearrangements by polymerase chain reaction. Gene rearrangements were not detected in the subdiagnostic group.

LIMITATIONS

Small study size was a limitation.

CONCLUSION

Flow cytometry of skin biopsy specimens is a sensitive method for detecting abnormalities in MF and should be considered part of the routine workup of patients with a clinical suggestion of MF.