Track

Case Reports

Abstract

Primary cutaneous CD8-positive aggressive epidermotropic cytotoxic T-cell lymphoma (PCAECTL) is a rare malignancy characterized by a clinically aggressive proliferation of CD8+ T lymphocytes with epidermotropism. Herein, we report a case of a 60-year-old male presenting with multiple necrotic plaques and patches on his trunk and extremities. Histomorphological analysis revealed epidermotropism of atypical lymphocytes with a dense lichenoid infiltrate in the superficial dermis. Immunohistochemistry showed a predominance of CD3+, CD8+ T cells with cytotoxic marker expression (granzyme B, TIA-1) within the epidermotropic lymphocytes., TCR-βF1 was expressed in the vast majority of the lymphocytes; however TCR-δ was observed in subset of larger, predominantly intraepidermal T-cells. Next-generation sequencing analysis detected a JAK/STAT3 gene fusion, consistent with JAK2 overactivation which has been observed in both CD8-PCAECTL and primary cutaneous gamma/delta T-cell lymphoma (PCGDTCL) cases. Although TCRαβ and TCRγδ share structural similarities, they belong to distinct sublineages of T cells and should not be expressed concurrently. While some cutaneous T-cell lymphomas exhibit co-expression of T cell receptors, the true significance of this phenomenon remains poorly understood due to its rarity. Considering the unusual TCR-δ expression, typically absent in PCAECTL, alternative diagnoses like PCGDTCL were considered. However, the predominance of TCR-βF1 expression, along with the clinical presentation and molecular profile, supports PCAECTL over PCGDTCL. TCR-delta expression in this context could be attributable to medication reactivity, normal reactive skin-resident TCRγδ T cells, or subclonal evolution. This case highlights the diagnostic complexity of rare cutaneous lymphomas and underscores the importance of precise diagnosis and clinicopathologic correlation.