Abstract

57-year-old Caucasian male with a history of Non-Hodgkin lymphoma presented to dermatology for evaluation of rapidly growing, painful back rash over the past five months. Previous biopsy returned inconclusive after review by multiple outside dermatopathologists. Physical exam revealed an ulcerated 16cm x 13cm pink-violaceous tumor with erythematous borders and central necrosis on the right upper back. A 6mm punch biopsy was performed at the lower right margin to rule out B-cell lymphoblastic leukemia (B-ALL) with cutaneous involvement versus recurrent Non-Hodgkin lymphoma versus deep fungal infection versus aggressive non-melanoma skin cancer. Histologic examination revealed a dense dermal lymphoid infiltrate composed of monomorphic small to medium cells with scant cytoplasm and fine chromatin and frequent mitotic figures. The cells were positive for CD20, CD79a, CD10, TdT, BCL2 and MYC and negative for CD3, CD7, CD34, CD56, Cyclin D1, CD123, EBER ISH. Given TdT expression, the immunohistochemical profile initially favored B-ALL. However, subsequent FISH analysis detected MYC and BCL2 rearrangements, most consistent with a High-grade B-cell Lymphoma with TdT expression. The patient was admitted to the inpatient hematology service for initiation of treatment. This case provided an opportunity for interdisciplinary collaboration with hematopathologists, hematologists and oncologists. Furthermore, this is a challenging case as the features do not fit any of the current WHO 2016 classifications. Although few reports of High-grade B-cell Lymphoma with TdT expression have been reported in the literature, preliminary studies indicate aggressive behavior and thus this entity must be distinguished from B-ALL, as treatment and prognosis differ.

Financial Disclosure:
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