Recurrent Primary Cutaneous Anaplastic Large Cell Lymphoma With T-Cell Receptor-ϒδ Phenotype and DUSP22-IRF4 Unbalanced Rearrangement: A Rare and Diagnostically Challenging Presentation.

Primary cutaneous anaplastic large cell lymphoma (pcALCL) is an indolent CD30+ T-cell lymphoma, typically of T-cell receptor (TCR)-αβ origin with an excellent prognosis. Rare cases may exhibit a TCR-ϒδ phenotype or rearrangement of the DUSP22 and IRF4 genes on chromosome 6p25.3, but the concurrence of both features is exceedingly rare. We present herein a case of a 78-year-old man with a history of pcALCL who, 5 years after achieving complete remission with radiation therapy, experienced a recurrent neck nodule. Histopathological examination revealed a dense dermal infiltrate of medium to large atypical lymphoid cells. The lesion was strongly positive for CD30, TCR-δ, and LEF1 but negative for CD4, CD8, CD7, TCR-β, and ALK, and TIA-1. p-STAT3 was predominantly negative with labeling of few scattered cells. Fluorescence in situ hybridization studies confirmed a DUSP22-IRF4 abnormality. In view of immunohistochemical findings (LEF1+, TIA-1-, predominantly p-STAT3-), an unbalanced DUSP22-IRF4 rearrangement was favored. A diagnosis of pcALCL with TCR-ϒδ phenotype and DUSP22-IRF4 unbalanced rearrangement was rendered. This case adds to the small but growing number of reported cases of pcALCL with TCR-ϒδ phenotype and DUSP22-IRF4 alteration.