Abstract

Cases of patients with PAX5-negative Hodgkin Lymphoma (HL) who subsequently developed peripheral T-cell lymphoma with shared TP53 point mutations have been reported in the literature. We present a case of a 63-year-old man with a history of stage IVB PAX5-negative HL with lung, liver, spleen, and bone marrow involvement. He achieved a complete metabolic response following completion of chemotherapy. Eight months later he developed progressive, cutaneous nodules involving the feet and lower legs. Staging evaluation including peripheral blood flow cytometry and PET-CT imaging failed to reveal systemic disease. Lesional biopsies demonstrated an atypical dermal lymphoid infiltrate composed of small-medium sized cells with epidermotropism, angiotropism and associated angiodestruction. There was marked vacuolar interface change and apoptotic keratinocytes. The atypical lymphoid cells were immunoreactive for CD2, CD3, CD30 (patchy; 20%) TCR-β and Granzyme-B and negative for CD8, CD4, CD5, CD7, CD56, CD15, TCR-δ, and TIA1. EBV RNA in situ hybridization studies were also negative and a diagnosis of primary cutaneous cytotoxic T-cell lymphoma was rendered. Although, the neoplastic cells were morphologically different from the patient’s previous HL and expressed a clonal T-cell receptor gene rearrangement that was not seen in his prior lymph node specimens, Foundation One Next Generation sequencing of the patient’s HL lymph node and his skin specimen revealed common MAPK1 A189V and TP53 C2338W, R213 mutations. These findings suggest a common founder cell for both lymphomas and raises questions as to true cell of origin of PAX5-negative Hodgkin-like lymphoma.

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