Abstract
Lymphomatoid papulosis (LyP) is a CD30 positive lymphoproliferative disorder with multiple histopathologic subtypes. Of these, LyP with 6p25 rearrangement is recently described where the morphology resembles transformed mycosis fungoides. Herein, we report a 73-year-old male who presented with a painful nodule on his right proximal arm 11 years ago that later self-resolved. Histologically, the lesion demonstrated an atypical CD30 positive T-cell infiltrate. The epidermatropic component was composed of small cells while the dermal component was composed of large cells. T-cell receptor gene rearrangements were negative and no IRF4-DUSP22 rearrangements were identified. Instead, an IRF4 amplification was noted. The patient was clinically worked up for systemic anaplastic large T cell lymphoma but showed no evidence of systemic disease . 10 months later he presented with recurrence several centimeters away. This was treated with radiation and resolved. 7 years later he presented with poorly defined plaques on his left upper arm and right lower abdomen with similar histology. The patient then had his most recent recurrence 3 years later on his right proximal arm, which also resolved spontaneously. DUSP22-IRF4 rearrangement is associated with a subset of primary cutaneous -ALCL, and a smaller subset of LyP. On the other hand, IRF4 gene amplification is less specific and has been reported in a wider range of T-cell lymphoproliferative processes including few cases of LyP. The histomorphology of these cases has not been characterized. In this report, we aim to expand the molecular findings of LyP with transformed MF like morphology. This case also emphasizes that long term clinicopathologic correlation might be necessary before the diagnosis of LyP can be rendered.
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