Abstract

Lymphomatoid papulosis (LyP) is a rare chronic and recurrent T-cell indolent lymphoma. Clinically, it usually presents as small multifocal papules or nodules that can ulcerate or bleed and self-resolve within 6 weeks of initial onset. LyP with DUSP22-IRF is unique as it is the only subset with a recurrent cytogenetic rearrangement and presenting in older patients. Within the differential diagnosis of LyP are CD30 positive T-cell lymphomas including anaplastic large cell lymphoma (ALCL) as well as mycosis fungoides (MF). Clinically, if the papules self-resolve, the most likely diagnosis is LyP. We report on a 66-year-old male that presented with papules and nodules, 2 of which were on the extremities (arms) and one of which on the shoulder. Histologically, all three specimens were ve biopsies that demonstrated a lymphomatoid infiltrate composed of small to medium sized cells with scattered large cells with epidermotropism. There is a subset of cells with a reniform morphology. Immunohistochemically, the cells of interest were positive for CD30, CD3, CD7 (partial), and T-cell receptor (TCR) GM1 and negative for CD4/8 double negativity, CD2, CD5, TIA1, Granzyme B, TCR BF1, TdT, ALK, and CD56. EBER (in-situ hybridization) was negative and Ki-67 proliferation index was 80%. Cytogenetic demonstrated DUSP22-IRF4 rearrangement. To date, there have been less than 20 reported cases, all of which are 60+ years old with a strong male predominance, typically presenting with one papule, and TCR BF1 positive (75%). We present a rare case of LyP DUSP22-IRF4 presenting with multiple nodule and TCR BF1 negative.