Abstract

Lymphomatoid papulosis (LyP) encompasses a spectrum of primary cutaneous CD30+ T-cell lymphoproliferative disorders with indolent course and spontaneous regression. LyP with DUSP22-IRF4 rearrangement is a recently identified variant of LyP.  Herein, we report a case of LyP with DUSP22-IRF4 rearrangement in a patient with a diagnosis of primary cutaneous ALCL 20 years prior. An 81-year-old female presented with a 10 mm erythematous papule on the abdomen. Biopsy showed a wedge-shaped, biphasic infiltrate of large dermal cells and epidermotropic small cells. The large and small cells were CD8+ T-cells with loss of CD7 and CD5. CD30 was strong in large dermal lymphocytes but weak in small epidermotropic lymphocytes. ALK was negative. FISH revealed rearrangement of DUSP22-IRF4. T-cell receptor gamma gene rearrangement assay identified a clonal population, identical to the prior ALCL. The ALCL tissue block was discarded per hospital policy, precluding FISH testing. The remaining slides were reviewed, showing a nearly identical immunophenotype with global loss of CD7 and CD5. However, a population of CD4+ larger, pleomorphic cells was noted; these cells were not present in the recent biopsy. Clinically, the ALCL was larger (>2 cm), ulcerated, and did not regress. Curiously, there was suggestion of other non-biopsied lesions at this time which spontaneously resolved. Up to 20% of patients can develop an associated lymphoma before, after, or during the course of disease, likely encompassing the prior diagnosis. Recognition of this rare subtype of LyP, with its characteristic differential CD30 expression and biphasic pattern, is important to properly classify these lesions.